Technical examination of vessels. Aspects of pressure vessel testing. Hydraulic and pneumatic testing of pressure vessels
RD 24.200.11-90
Group T58
GUIDANCE DOCUMENT
VESSELS AND APPARATUS WORKING UNDER PRESSURE
Rules and safety standards for hydraulic testing
for strength and tightness
OKSTU 3602
Introduction date 1991-07-01
INFORMATION DATA
1. DEVELOPED AND INTRODUCED
All-Union Scientific Research and Design Institute of Technology of Chemical and Petroleum Apparatus (VNIIPTkhimnefteapparatura)
DEVELOPERS:
V.P. Novikov (head of the theme); N.K.Lamina; A.M. Eremin
2. APPROVED AND INTRODUCED by the order of the Ministry of Heavy Engineering of 25.07.90 N BA-002-7259
3. REGISTERED by NIIkhimmash for N RD 24.200.11-90 of 06/19/1990
4. Information on the timing and frequency of document verification: The term of the first verification is 1992, the frequency of verification is 2 years
5. INTRODUCED FOR THE FIRST TIME
6. REFERENCE REGULATIONS AND TECHNICAL DOCUMENTS
Number of paragraph, subparagraph, enumeration, application |
|
3.2.26; 3.2.29 |
|
OST 26-01-9-80 |
Introduction |
OST 26-01-221-80 |
Introduction |
OST 26-01-900-79 |
Introduction |
OST 26-01-1183-82 |
Introduction |
OST 26-11-06-86 |
Introduction |
OST 26-11-14-88 |
|
OST 26-18-6-80 |
Introduction |
This guidance document establishes the rules and safety standards for the preparation and conduct of hydraulic tests for strength and tightness of pressure vessels and apparatus manufactured in accordance with the requirements of OST 26-291 *, OST 26-01-1183, OST 26-01-900 , OST 26-11-06, OST 26-18-6, OST 26-01-9, OST 26-01-221.
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* Valid OST 26-291-94
Hydraulic testing of products and their elements for strength and tightness by hydrostatic pressure should be carried out on special test hydraulic stands (hereinafter referred to as hydraulic stands) or, in exceptional cases, on assembly stands using portable equipment.
1. GENERAL PROVISIONS
1. GENERAL PROVISIONS
1.1. The guidance document applies to all methods of hydraulic testing according to OST 26-291 and OST 26-11-14.
1.2. At each enterprise, in accordance with this guidance document, instructions for the safe conduct of hydraulic tests should be developed and approved by the chief engineer. The main provisions of the instruction, as well as the test scheme, must be posted at the workplace of each hydrotest site.
2. REQUIREMENTS FOR PERSONNEL
2.1. To work on hydraulic stands and workplaces with portable equipment for hydraulic testing, workers of the corresponding specialty are allowed according to the "Unified Tariff and Qualification Reference Book of Works and Professions of Workers (ETKS), certified in the prescribed manner with a qualification of at least 4 categories".
2.2. The appointment or transfer of a worker is carried out by order in the workshop.
The worker must be familiar with the features of this test equipment and be instructed.
The organization of training and instruction in labor safety must comply with the requirements of GOST 12.0.004*.
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GOST 12.0.004-90, hereinafter in the text. - Database manufacturer's note.
2.3. Re-testing the knowledge of workers should be carried out at least once a year for workers and once every three years for engineers by a factory qualification commission appointed in the prescribed manner.
2.4. Responsibility for good condition, correct and safe operation the hydrostand is assigned to an engineering and technical worker (ITR), appointed by order for the workshop (enterprise) and certified in the prescribed manner.
2.5. Each hydraulic stand in each shift must be assigned to a separate executor by an order for the workshop. The contractor is obliged to monitor the good condition of the hydraulic stand and keep it in proper order and cleanliness. Each hydraulic stand must have a sign indicating the name of the contractor responsible for this hydraulic stand.
2.6. In preparation for hydraulic testing of each product of a new type, design, etc. the work manager must conduct an unscheduled briefing of workers on the features of this product, point out possible sources of danger and precautions.
2.7. To perform work on slinging and moving cargo, controlling lifting mechanisms from the floor, testers must have an appropriate certificate.
2.8. Testers must be provided with overalls and safety shoes of the appropriate size according to standard industry standards for machine-building and metalworking industries.
3. REQUIREMENTS FOR THE SITE, EQUIPMENT, RIGGING
3.1. Requirements for the site and workplace when testing with portable equipment
3.1.1. The site for hydraulic testing must comply with the requirements of the current sanitary standards for the design of industrial enterprises CH118, CH119, CH245, building codes and rules SNiP2, SNiP8, SNiP9.
3.1.2. The area of the site should provide accommodation for:
hydraulic stand (or portable equipment when tested on an assembly stand);
auxiliary equipment and accessories;
of the product under test, taking into account the safe performance of work on its installation and inspection, while the free zone along the perimeter of the maximum possible dimension of the product must be at least 1 m.
3.1.3. The site must have a non-slip floor covering with a slope and (or) holes for water drainage, as well as a protective fence that excludes the possibility of accidental appearance on the site of unauthorized persons and the ingress of working fluid outside the site (Appendix 2).
On the fence there should be a light board with the inscription "NO ENTRY. TESTING IN PROGRESS" or a corresponding poster.
3.1.4. The site must have general and local working lighting, emergency lighting, as well as portable lamps with a voltage of not more than 42 V. Lighting equipment must comply with the requirements of the Electrical Installation Rules.
Lighting should provide illumination on the surface of the product under test:
working - at least 300 lux with fluorescent or 200 lux with incandescent lighting;
emergency - at least 10% of the working one.
3.1.5. The hydraulic testing site must have a circulating water supply system that ensures filling the volume of the tested products or a technical water supply system with a drain system to the sewer.
3.1.6. Workplace where hydraulic testing is carried out with portable equipment, must comply with the requirements of paragraphs 3.1.2-3.1.6 of this guidance document.
It is allowed to use a handrail as a temporary protective fence, installed from the tested product at a distance not less than the calculated one (Appendix 3.)
3.2. Requirements for equipment and accessories
3.2.1. The hydraulic stand must be equipped with:
capacity for working fluid with its circulation system;
a pump for filling and emptying the product;
a pump to create pressure in the product;
receiver (buffer tank) or pneumohydroaccumulator;
pipeline system;
stop valves;
instruments for measuring the pressure and temperature of the working fluid;
safety devices or electrocontact manometers (ECM);
plugs.
The electric motors of the pumps must be enclosed, type IP44.
Allowed use pumping unit with a pneumatic actuator with a solenoid valve (electric valve) blocking the air supply to the pneumatic actuator. The valve must be controlled by an electric contact pressure gauge (ECM) installed in the line from the pump to the product.
When using phosphors, preservatives or other chemicals as part of the working fluid, the hydraulic stand must be additionally equipped with special containers for preparing neutralizing solutions and neutralizing the working fluid and (or) a device for collecting these substances for their further use.
3.2.2. The location and layout of the equipment must meet the requirements of the current building codes and regulations SNiP9, SNiP10 and ensure the safety and convenience of its operation and repair.
The control panel of a hydraulic stand or portable hydrotesting equipment located in a hazardous area determined by the calculation in Appendix 3 must be equipped with protection calculated in accordance with Appendix 2.
3.2.3. When the test product is located underground, a sliding or other mechanical roof should be provided above the buried room, and the area, taking into account the area occupied by the roof in the open position, should have a railing.
3.2.4. The electrical equipment of the hydraulic stand must comply with the requirements of the "Rules for the Arrangement of Electrical Installations", "Rules for the Technical Operation of Consumer Electrical Installations", "Safety Rules for the Operation of Consumer Electrical Installations" *, as well as building codes and rules SNiP6.
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* The "Intersectoral Rules for labor protection (safety rules) for the operation of electrical installations" (POT R M-016-2001, RD 153-34.0-03.150-00) are in force. - Database manufacturer's note.
3.2.5. The hydrostand must be equipped with "STOP" buttons for emergency stop of the pump motor, painted in red. The number of buttons and their location must ensure that the motor can be stopped quickly.
3.2.6. The rotating parts of the feed pump drive must be securely guarded. Contact of working liquid on the drive is not allowed.
3.2.7. The pressure line of the pump must have a receiver to reduce pressure fluctuations in the product under test caused by the pulsating supply of the working fluid. The receiver must be designed for pressure not lower than the maximum allowable for this hydraulic stand.
The receiver must be installed at the hydrotest site in a place that excludes the presence of people and ensures its accessibility for inspection, and has a protective fence designed in accordance with Appendix 2.
It is allowed not to install the receiver and bypass on the hydraulic stands if the pressure in the product under test is reached using a pump without an electric drive (manually).
3.2.8. The location of pipelines should provide free access for inspection and control of their condition.
3.2.9. The pressure measurement should be carried out using two verified pressure gauges, one of which, the control one, should be installed on the product, and the second one - on the control panel of the hydraulic stand.
3.2.10. Manometers for measuring pressure must have the same type, measurement limit, the same division value and an accuracy class of at least:
2.5 at design pressure up to 2.5 MPa (25 kgf/cm);
1.5 at design pressure over 2.5 MPa (25 kgf/cm) and such a scale on which the measurement limit of design pressure is in its second third.
3.2.11. The location of the pressure gauges should provide a free view of the pressure gauge scale, while the instrument scale should be in a vertical plane.
The nominal diameter of the case of pressure gauges installed at a height of up to 2 m from the level of the observation site for them must be at least 100 mm, at a height of 2 to 3 m - at least 160 mm. Installation of pressure gauges at a height of more than 3 m from the level of the site is not allowed.
3.2.12. Pressure gauges must be protected from thermal radiation, freezing, mechanical damage.
3.2.13. It is forbidden to use pressure gauges for:
the absence of a seal or brand with a mark on the verification carried out;
overdue verification period;
malfunctions of the pressure gauge (the pointer does not return to the zero mark of the scale when it is turned off, the glass is broken or there are other damages that may affect the correctness of the readings).
3.2.14. The safety valves of the hydraulic bench must have a capacity corresponding to the performance of the hydraulic pumps, be adjusted to the test pressure, checked for the tightness of the gate and detachable connections and sealed together with a tag indicating the test pressure.
Valve adjustment must be carried out in accordance with GOST 12.2.085 *. The control medium for determining the valve opening moment can be air or water, which must be clean, without mechanical or chemical impurities.
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* In the territory Russian Federation GOST 12.2.085-2002 is valid. - Database manufacturer's note.
3.2.15. The installation of safety valves must be carried out in accordance with the "Rules for the Design and Safe Operation of Pressure Vessels" and in accordance with circuit diagram hydrostand equipment or a schematic diagram approved by the chief engineer of the enterprise.
It is allowed to use electrocontact pressure gauges (ECM) instead of safety valves, while one pressure gauge is installed on the product and one more - in the line from the pump to the product. The connection of the pump with the pressure gauge EKM must be carried out through a buffer tank or a damping device to protect the pressure gauge from the pulsation of the working fluid in the pipeline.
Pressure gauges must be set to the test pressure and ensure that the pump is turned off when the test pressure is reached.
3.2.16. Rubber, metal-rubber hoses and pipelines used in hydraulic testing must have tags indicating their working and test pressure, test period.
The pressure values on the sleeves and pipelines must not be lower than the pressure value for which this hydraulic stand is designed.
Sleeves must comply with current standards or specifications and not have mechanical or chemical damage.
3.2.17. The stop valves of the hydraulic stand must be accessible for maintenance and located no higher than 1.5 m from the floor level. The fittings must be systematically lubricated and scrolled, while the use of any levers is not allowed.
Use fittings that do not have technical documentation(passport, certificate, etc.) is not allowed.
3.2.18. Shut-off valves must be clearly marked:
manufacturer's name or trademark;
conditional pass, mm;
nominal pressure, MPa (kgf/cm);
medium flow direction;
material grade.
3.2.19. The marking of the plugs used for hydrotesting should indicate the number of the plug and the pressure value for which it is designed.
3.2.20. The product under test must have:
valve or cock to control the absence of pressure in it before dismantling it. It is allowed to use a three-way valve installed on the product. The outlet of the tap must be directed to a safe place. It is allowed not to install a valve or tap if there are couplings for draining the liquid;
safety valves, quantity and throughput which should exclude the possibility of a pressure exceeding the test pressure in the product. It is allowed to use safety valves with a rupture disc designed for test pressure.
It is allowed not to install safety valves on the product if they are provided in the line between the pump and the tested product and are designed for test pressure.
3.2.21. The working fluid leaving the safety valve must be drained to a safe place. The installation of locking devices on the outlet pipes, as well as between the product and the safety valve is not allowed.
3.2.22. Working fluids used for hydraulic testing must be non-toxic, non-explosive, non-flammable.
It is allowed, at the request of the product developer, to use other liquids with the obligatory observance of the relevant safety measures.
3.2.23. The structures of service platforms and ladders to them (scaffolding) must comply with the current "Safety regulations for construction and installation work" and " General rules safety precautions and industrial sanitation for enterprises and organizations of mechanical engineering".
3.2.24. Cranes and mechanisms used at the hydraulic testing site must comply with the requirements of the current "Rules for the Construction and Safe Operation of Cranes".
3.2.25. The hydraulic stand and all assembly units, units and devices included in it must have certificates or passports. The use of technological equipment that does not have technical documentation and (or) with mechanical damage to the threaded, sealing, seating surfaces, signs of stretching, is not allowed.
3.2.26. The hydraulic stand must be certified in accordance with GOST 24555 * and accepted by the commission appointed by the order for the enterprise.
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* On the territory of the Russian Federation, GOST R 8.568-97 applies, hereinafter in the text. - Database manufacturer's note.
Certification documentation is developed by the stand developer and agreed with the metrological service of the enterprise before certification of the hydro stand.
Testing of the hydraulic stand must be carried out with a pressure equal to 1.25 of the pressure for which the hydraulic stand is designed.
Technical documentation must be attached to the certificate for the hydraulic stand:
attestation protocol (Appendix 1);
calculations of the elements of the stand for strength;
passports and certificates for devices, units and fittings used at the stand;
safety instructions for working on the hydraulic stand;
order to appoint a person responsible for the hydraulic stand.
3.2.27. The technical documentation for the hydraulic stand must be kept by the person responsible for its good condition and safe operation (see clause 2.4).
3.2.28. The hydrostand must be registered with the metrological and technical service of the enterprise, which carries out scheduled preventive repairs.
3.2.29. The hydrostand must be periodically, once every 6 months, subject to inspection and at least once a year - repair.
Scheduled preventive repairs must be carried out in strict accordance with the schedule approved by the chief engineer of the enterprise. After repair, the hydraulic stand must be subjected to a hydraulic pressure test in accordance with clause 3.2.27 and certified in accordance with GOST 24555.
3.2.30. Verification of pressure gauges with their sealing or branding should be carried out at least once a year in the prescribed manner.
Additional verification of working pressure gauges with a control one should be carried out at least once every 6 months with the results recorded in a journal. It is allowed to use a certified working pressure gauge for verification of working pressure gauges, which has the same scale and accuracy class with the verified one. Regardless of the indicated terms, the verification of pressure gauges must be carried out if there is any doubt about the correctness of their readings.
3.2.31. Checking of safety valves should be carried out at least once a year, within the time limits established by the management of the enterprise. Checking, repairing and adjusting the safety valve must be documented by an act signed by the workshop mechanic, the repair and adjustment foreman and the locksmith who carried out these works.
The safety valve that has been repaired and adjusted must be sealed together with a tag indicating the test pressure and provided with a number.
Each safety valve must have technical certificate, along with which copies of the passports for the valve and spring from the supplying factories, as well as copies of the acts of its verification, repair and adjustment should be kept.
3.2.32. Rubber, metal-rubber hoses and pipelines must be checked and tested at least once a year according to the preventive maintenance schedule. Tests must be carried out in accordance with the relevant regulatory and technical documents for these products and building codes and regulations.
3.2.33. Shut-off valves after each repair must be tested for mechanical strength and tightness with hydraulic pressure that meets the requirements of the regulatory and technical documentation for this valve, but not lower than the maximum pressure for which the hydraulic bench is designed. The test of shut-off valves must be formalized by an act.
Tests should be carried out after fitting and fitter-machining.
4. SAFETY REGULATIONS FOR HYDRAULIC TESTING
4.1. Preparation for hydraulic testing
4.1.1. Products and their elements subject to hydrotesting must be accepted by the quality control department based on the results of an external examination and non-destructive testing.
The value of the test pressure for the product must not exceed the maximum allowable pressure for which the hydraulic stand is designed.
4.1.2. Fasteners and seals used in hydrotesting must be made of materials provided for in the working drawings for the product.
4.1.3. Instrumentation, safety devices, fittings, plugs, fasteners, gaskets, etc. must be selected according to the marking for a pressure not lower than the test one.
4.1.4. When installing the product under test on a hydraulic stand on standard or technological supports, its stable position, free access for inspection and the location of drainage holes ("air vents") at its upper point must be ensured.
Hydrotest scheme, technological process and equipment must ensure complete removal of air when filling the product under test with a working fluid.
4.1.5. Installation of communications, installation of the required fittings, instrumentation must be carried out in full accordance with the approved hydraulic testing scheme.
All free openings of the product under test shall be plugged.
Installation, equipment and inspection of the product at a height of more than 1.5 m should be carried out from special sites (scaffolding).
4.1.6. When mounting flanged connections, the threaded elements must be tightened evenly, alternately tightening diametrically opposite ("crosswise"), while maintaining the parallelism of the flanges.
Do not use wrenches that do not match the size of the nut, non-standard and / or with a handle extension, as well as a hammer or sledgehammer.
4.1.7. When preparing a working fluid using phosphors, preservatives, as well as when applying indicator coatings to the controlled surfaces of the tested product, a system of general exchange supply and exhaust ventilation must be switched on in the hydrotesting area.
4.2. Carrying out hydraulic tests
4.2.1. A minimum number of people, but not less than two people, should participate in hydraulic testing.
4.2.2. During hydrotesting it is prohibited:
be on the territory of the site to persons not participating in the test;
be from the side of the plugs to the persons participating in the test;
carry out extraneous work on the territory of the hydraulic testing site and work related to the elimination of detected defects on a product under pressure. Repair work may only be carried out after the pressure has been relieved and, if necessary, the working fluid has been drained;
transport (turn over) a product under pressure;
transport loads over a pressurized product.
4.2.3. The tester is prohibited from:
to carry out tests on a hydraulic stand that is not assigned to him or his team by order in the workshop;
leave without supervision the control panel of the hydraulic stand, the product under test connected to the water supply system (even after the pressure has been removed);
perform under pressure assembly and disassembly of products, equipment, repair of equipment of the hydraulic stand, etc.;
to arbitrarily make changes to the technological process of testing, change the pressure or holding time under pressure, etc.
4.2.4. Hydraulic testing on an assembly stand using portable equipment is allowed in exceptional cases with the written permission of the chief engineer of the enterprise and compliance with the requirements of this guideline.
4.2.5. The product under test must be completely filled with the working fluid, the presence of air cushions in communications and the product is not allowed.
The surface of the product must be dry.
4.2.6. The pressure in the product should rise and fall smoothly. The increase in pressure should be carried out with stops (for the timely detection of possible defects). The value of the intermediate pressure is taken equal to half of the test pressure. The rate of pressure rise should not exceed 0.5 MPa (5 kgf/cm) per minute.
The maximum deviation of the test pressure should not exceed ± 5% of its value. The exposure time of the product under test pressure is set by the project developer or indicated in the regulatory and technical documentation for the product.
4.2.7. It is forbidden to be near and (or) inspect the product during the increase in pressure to the test pressure and holding the product under test pressure. The personnel participating in the test must be at the control panel at this time.
Inspection of the product should be carried out after the pressure in the product is reduced to the calculated one.
At the design pressure in the product, it is allowed to be at the hydraulic stand:
testers;
defectoscopists;
representatives of the technical control department (TCD);
responsible for safe holding works - foreman, senior foreman, site manager;
heads of departments;
employees of leading technical departments;
customer representatives.
These persons must undergo special training or appropriate instruction in accordance with GOST 12.0.004.
4.2.8. When using flaw detection equipment with sources of ultraviolet radiation, exposure of the eyes and skin of workers is not allowed.
4.2.9. The tester is obliged to interrupt the test, turn off the pumps that create pressure, or shut off the valves of the pipelines supplying pressure to the product (when using one pump for several workplaces) and open the pressure relief valves when:
interruption in the supply of working pressure;
reaching a pressure in the product or pipelines higher than permitted despite compliance with all the requirements specified in the instructions;
failure of pressure gauges or other indicating instruments during pressure rise;
actuation of safety devices;
the occurrence of water hammer in the pipeline or product, the appearance of vibration;
detection of leaks, cracks, bulges or sweating in welds in the tested product, technological equipment, pipelines;
leakage through the drainage holes, which serves as a signal to terminate the test;
destruction of the tested product;
fire, etc.
4.2.10. After depressurizing the system, before disassembling the flange connections, it is necessary to remove the working fluid from the product and the system.
4.2.11. When dismantling the tooling, the nuts of the bolted connections should be removed, gradually loosening the diametrically opposite ones (“crosswise”), and pay attention to the integrity of the sealing elements in order to prevent them from falling into the internal cavities of the product.
4.2.12. Spent working fluid containing chemicals before being discharged into sewer network must be neutralized and/or purified.
Discharge into the sewer of working liquids containing phosphors, preservatives, etc., which have not undergone neutralization and (or) purification, is prohibited.
When working with a solution of bleach at the site of hydrotesting, the system of general exchange must be turned on. supply and exhaust ventilation. The exhaust pipe of the ventilation system must be located directly above the container with the bleach solution.
Chlorine lime that has fallen on the floor should be washed off with water into the sewer drain.
All work with bleach should be carried out in goggles, a canvas suit, rubber boots and gloves, with a gas mask on.
4.2.13. Removal of fluorescein-based phosphors and its solutions (suspensions) from the skin should be done with soap and water or 1-3% aqueous ammonia solution.
Upon completion of work with phosphors, personnel must thoroughly wash their hands with warm water and soap.
1. CHARACTERISTICS OF THE HYDROSTAND
Design pressure, MPa (kgf/cm) |
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Permissible working pressure, MPa (kgf/cm) |
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Design temperature, °C |
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Characteristics of the working agent |
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(water, neutral liquids, etc.) |
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They represent an increased danger, since the medium in them is under excess pressure exceeding 0.7 atm. Most often they explode when the allowable pressure is exceeded. All devices operating under high blood pressure after manufacturing and installation, they undergo an appropriate check and hydraulic tests. During visual inspection, attention is paid to the tightness of the seams, the integrity of welded, riveted, bolted joints, and the absence of corrosion. Inspection of devices is carried out at least once every 4 years. Hydraulic testing is carried out by filling the apparatus with water at a pressure of 1.25-1.5 times the operating pressure and holding for 10-30 minutes. At the same time, attention is paid to the appearance of deformations, smudges and drops of water on the outer part of the apparatus. It is advisable to pay attention to the pressure loss in the apparatus on the pressure gauge. Hydraulic tests are carried out at least once every 8 years. After installation and testing of the apparatus, which is carried out in the presence of state technical supervision, it is applied to the apparatus with paint registration number, admissible pressure, date of the subsequent test. The device must be equipped with a pressure gauge, shut-off valves. Place such devices on the street or in separate buildings.
To ensure stable and safe operation of pressure vessels, they are subjected to technical examination: internal inspection and hydraulic test before commissioning, periodically during operation and ahead of schedule. Vessels registered with the supervisory authorities are checked by a boiler inspector. If the design features of the vessel do not allow an internal inspection, it is replaced by a hydraulic test, test pressure and inspection in accessible places. If, however, a hydraulic test turns out to be impossible (for example, due to high stresses from the weight of water in the foundation, interfloor ceilings or the vessel itself, the presence of a lining inside the vessel that prevents filling with water, difficulty in removing water, etc.), it is allowed to produce pneumatic test (air or inert gas) at the same test pressure. At the same time, a pneumatic test (with compressed air) is allowed only subject to satisfactory results of a thorough internal inspection, verification of the strength of the vessel by calculation and the implementation, under strict control, of certain safety measures (outside the room where the vessel is tested, the valve on the filling pipeline from the pressure source and pressure gauge , removal of people to safe places for the period of testing the vessel with test pressure, etc.). The vessel is under test pressure for 5 minutes, after which the pressure is gradually reduced to working pressure, the vessel is inspected, the tightness of its seams and detachable joints is checked with a soap solution or other effective way. Tapping a pressure vessel during a pneumatic test is dangerous and prohibited.
It is allowed not to perform a hydraulic test during the technical examination of new vessels, if 12 months have not passed since such a test carried out at the manufacturer's plant, if they were not damaged during transportation and installation, and their installation was carried out without welding or soldering elements operating under pressure.
The rules establish that the vessels in operation and registered with the Gosgortekhnadzor bodies are subject to periodic technical examination by the inspector, including: hydraulic test with a preliminary internal inspection - at least once every 8 years, while it is allowed to use water or other non-corrosive, non-poisonous, non-explosive, non-viscous liquids.
Early technical inspection of vessels is necessary after reconstruction and repair using welding or soldering separate parts working under pressure; if the vessel was inactive for more than 1 year before putting into operation (with the exception of cases of storage conservation, in which the survey of vessels is mandatory before putting into operation when stored for more than 3 years); if the vessel was dismantled and installed in a new place; before applying a protective coating to the walls of the vessel (if it is produced by its owner); if an early survey is necessary at the discretion of the inspector, the person exercising supervision, or the person responsible for the good condition and safe operation of the vessel. Periodic and extraordinary technical examination of vessels is carried out by the Kotlonadzor inspector without fail in the presence of an employee of the supervision bureau (department) or another certified engineering and technical employee appointed by the administration, as well as the person responsible for the safe operation of these facilities. At the same time, the administration of the enterprise must notify the inspector at least 10 days in advance of the readiness of the vessel for examination. If the inspector for any reason does not appear at the appointed time, the administration has the right to appoint by order of the enterprise a commission of experienced, certified specialists to conduct a technical examination. Its results, as well as the date of the next examination, are entered in the passport. A copy of the record is sent to the local Gosgortekhnadzor body no later than 5 days later. The vessel admitted to work is subject to survey not later than in 12 months. The administration of the enterprise, in addition to surveys of the inspector, conducts:
internal inspection and hydraulic testing before putting into operation of all newly installed vessels, except for those that are examined by the inspector;
internal inspection of all registrants. and non-registered vessels at least every 2 years, with the exception of vessels that operate in an environment that causes metal corrosion and must be subjected to internal inspection at least every 12 months.
Internal inspection of vessels included in systems with a continuously operating technological process, with a non-corrosive working medium, the shutdown of which is impossible due to production conditions, may be combined with overhaul or replacement of the catalyst, but at least once every 4 years. During internal examinations of vessels, all defects that reduce their strength should be identified and eliminated;
periodic inspection of vessels in working order;
hydraulic test with a preliminary internal inspection of vessels that are not registered with the supervisory authorities - at least once every 8 years; early technical examination of unregistered vessels. When preparing for inspections and hydraulic tests, the vessel should be cooled (warmed up), freed from the filling working medium, disconnected with plugs from all pipelines connecting it to pressure sources or other vessels, cleaned of metal. Lining, insulation and other protection of vessel surfaces are partially or completely removed in cases where there are signs of defects in the metal of the vessel under a protective coating, for example: leakage of the lining, bulges in the rubberized layer, traces of leakage of insulation, etc. All fittings are thoroughly cleaned before the hydraulic test and lapped, and covers, hatches, etc. are installed firmly and tightly, excluding the possibility of leakage.
Dangerous areas of equipment.
Dangerous area- this is a space in which it is possible to act on a working dangerous and (or) harmful production factor. The danger is localized in the space around the moving elements: cutting tool processed details, faceplate, toothed, belt and chain drives, work tables of machine tools, conveyors, moving hoisting and transport machines, loads, etc. A particular danger is created in cases where clothing or hair can be caught by moving parts of the equipment.
The presence of a dangerous zone may be due to the danger of electric shock, exposure to thermal, electromagnetic and ionizing radiation, noise, vibration, ultrasound, harmful vapors and gases of dust, the possibility of injury by flying particles of the material of the workpiece and tool during processing, the departure of the workpiece due to its poor fixing or breakdown.
The dimensions of the dangerous zone in space can be constant (the zone between the belt and the pulley, the zone between the rollers, etc.) and variable (the field of rolling mills, the cutting zone when changing the mode and nature of processing, changing the cutting tool, etc.).
During design and operation technological equipment it is necessary to provide for the use of devices that either exclude the possibility of human contact with the danger zone, or reduce the danger of contact (means of protection for workers). Means of protection of workers according to the nature of their application are divided into two categories: collective and individual.
Collective protection means, depending on the purpose, are divided into the following classes: normalization of the air environment industrial premises and workplaces, normalization of lighting of industrial premises and workplaces, means of protection against ionizing radiation, infrared radiation, ultraviolet radiation, electromagnetic radiation, magnetic and electric fields, radiation of optical quantum generators, noise, vibration, ultrasound, electric shock, electrostatic charges, from high and low temperatures of surfaces of equipment, materials, products, workpieces, from high and low air temperatures in the working area, from the impact of mechanical, chemical, biological factors.
Personal protective equipment, depending on the purpose, is divided into the following classes: insulating suits, respiratory protection, special clothing, special shoes, hand, head, face, eye, hearing protection, fall protection and other similar means, protective dermatological facilities.
All means of collective protection used in mechanical engineering working according to the principle of action can be divided into protective, safety, blocking, signaling, as well as systems remote control machines and special Each of the listed subclasses, as will be shown below, has several types and subspecies. The general requirements for protective equipment are: creating the most favorable relationships for the human body with the environment and ensuring optimal conditions for work; high degree of protective efficiency; taking into account the individual characteristics of equipment, tools, fixtures or technological processes; reliability, strength, ease of maintenance of machines and mechanisms, taking into account the recommendations of technical aesthetics.
44. Types of combustion, mechanisms of combustion processes.
Combustion- This is a chemical oxidation reaction, accompanied by the release of heat and light. For combustion to occur, three factors are required: a combustible substance, an oxidizing agent (usually atmospheric oxygen) and an ignition source (impulse). The oxidizing agent can be not only oxygen, but also chlorine, fluorine, bromine, iodine, nitrogen oxides, etc.
Depending on the properties of the combustible mixture, combustion can be homogeneous or heterogeneous. In homogeneous combustion, the initial substances have the same state of aggregation (for example, combustion of gases). Combustion of solid and liquid combustible substances is heterogeneous. -
Combustion is also differentiated by the speed of flame propagation and, depending on this parameter, it can be deflagration (of the order of tens of meters per second), explosive (of the order of hundreds of meters per second) and detonation (of the order of a thousand meters per second). Fires are characterized by deflagration combustion.
Depending on the ratio of fuel and oxidizer, combustion processes of lean and rich combustible mixtures are distinguished. poor mixtures containing an excess of an oxidizing agent are called. Their combustion is limited by the content of the combustible component. TO rich include mixtures with a fuel content above the stoichiometric ratio of components. The combustion of such mixtures is limited by the content of the oxidizing agent. The occurrence of combustion is associated with the obligatory self-acceleration of the reaction in the system. There are three main types of self-acceleration of a chemical reaction during combustion: thermal, chain and combined - chain-thermal. The thermal acceleration mechanism is associated with the exothermicity of the oxidation process and an increase in the rate of a chemical reaction with an increase in temperature, provided that heat is accumulated in the reacting system.
Chain acceleration of the reaction is associated with the catalysis of chemical transformations, carried out by intermediate products of transformations that have a special chemical activity and are called active centers. In accordance with the chemical chain theory, the process occurs not through the direct interaction of the initial molecules, but with the help of fragments formed during the decay of these molecules (radicals, atomic particles).
Real combustion processes are carried out, as a rule, by a combined chain-thermal mechanism. The combustion process is divided into several types.
Flash- rapid combustion of the combustible mixture, not accompanied by the formation of compressed gases.
fire- the occurrence of combustion of iodine by the influence of an ignition source.
Ignition- ignition, accompanied by the appearance of a flame.
Spontaneous combustion- the phenomenon of a sharp increase in the rate of exothermic reactions, leading to the combustion of a substance (material, mixture) in the absence of an ignition source. The essence and differences between the processes of ignition and spontaneous combustion are explained below.
Self-ignition- spontaneous combustion, accompanied by the appearance of a flame.
Explosion- an extremely fast chemical (explosive) transformation, accompanied by the release of energy and the formation of compressed gases capable of producing mechanical work. The occurrence of combustion of a substance or material can occur at a temperature environment below the ignition temperature. This possibility is determined by the tendency of substances or materials to oxidize and the conditions of accumulation in them of heat released during oxidation, which can cause spontaneous combustion. Thus, the occurrence of combustion of substances and materials when exposed to thermal pulses with a temperature above the ignition temperature (or spontaneous combustion) is characterized as ignition, and occurrence. combustion at temperatures below the auto-ignition temperature refers to the process of spontaneous combustion. Depending on the impulse, spontaneous combustion processes are divided into thermal, microbiological and chemical.
When assessing the fire hazard of substances and materials, it is necessary to take into account their state of aggregation. Since combustion, as a rule, occurs in a gaseous environment, it is necessary to take into account the conditions under which a sufficient amount of gaseous combustible products is formed for combustion as indicators of fire hazard. The main indicators of fire hazard, which determine the critical conditions for the onset and development of the combustion process, are the autoignition temperature and the concentration limits of ignition.
The autoignition temperature characterizes the minimum temperature of a substance or material at which a sharp increase in the rate of exothermic reactions occurs, ending in the onset of fiery combustion. The minimum concentration of combustible gases and vapors in the air at which they are able to ignite and spread a flame is called lower concentration limit of ignition; the maximum concentration of combustible gases and vapors at which flame propagation is still possible is called upper concentration flammable limit. The region of compositions and mixtures of combustible gases and vapors with air lying between the lower and upper limits of ignition is called the region of ignition.
Flammable concentration limits are not constant and depend on a number of factors. The greatest influence on the ignition limits is exerted by the power of the ignition source, the admixture of inert gases and vapors, the temperature and pressure of the combustible mixture.
flash point called the lowest (under special test conditions) temperature of a combustible substance at which vapors and gases are formed above the surface that can flare up in the air from an ignition source, but the rate of their formation is still insufficient for subsequent combustion. Using this characteristic, all flammable liquids can be divided into two classes according to fire hazard: the first includes liquids with a flash point up to 61 ° C (gasoline, ethyl alcohol, acetone, sulfuric ether, nitro enamels, etc.), they are called flammable liquids (LVZH); to the second - liquids with a flash point above 61 ° C (oil, fuel oil, formalin, etc.), they are called combustible liquids.
Flash point- the temperature of a combustible substance at which it emits combustible vapors and gases at such a rate that after igniting them from an ignition source, stable combustion occurs.
Temperature limits of ignition- temperatures at which saturated vapors of a substance form concentrations in a given oxidizing environment equal to the lower and upper concentration limits of liquid ignition, respectively.
Pressure vessels, steam and hot water boilers, steam pipelines hot water are treated in accordance with federal law"On industrial safety of hazardous production facilities" to hazardous production facilities. The manufacture of vessels and operation is regulated by: “rules for the design and safe operation of vessels operating under pressure” Operation is an increased danger. (explosions are especially dangerous: boilers, vessels, steam and hot water pipelines - great destruction, injuries, accidents, material damage).
The rules for the design and safe operation of pressure vessels, boilers, steam and hot water pipelines are usually called the Boiler Supervision Rules, and the objects to which they apply are boiler supervision objects. (control - Rostekhnadzor of the Russian Federation; at the enterprise and in organizations, control over compliance with the Boiler Supervision Rules is carried out by boiler supervision inspectors who conduct technical certification and inspection of boiler facilities. - failure to comply with the rules is punishable by fines. (responsibility for compliance with the rules, condition and operation of vessels is the responsibility of managers and specialists supervising the technical condition and operation of the vessels.))
Vessel - a hermetically sealed container, designed for conducting chemical, thermal and other technological processes, as well as storage, transportation of gaseous, liquid and other substances. The boundary of the vessel is the inlet and outlet fittings.
Trial pressure is the pressure at which the vessels are tested.
Operating pressure - the maximum internal excess or external pressure that occurs during the normal course of the working process.
Design pressure - the pressure used in the strength calculation.
Conditional pressure - design pressure at a temperature of 20 C, used in the calculation of the strength of standard vessels.
The main causes of accidents of vessels, work under pressure.
The main causes of accidents:
- a) a significant excess of pressure due to a malfunction of the safety valves, a violation of the technological process or the ignition of oil vapors in the air collectors, the absence (malfunction) of reducing devices;
- b) malfunction or absence of safety devices for vessels with quick-release lids;
- c) defects in the manufacture, installation and repair of vessels;
- d) overflow of vessels with liquefied gases;
- e) wear of vessel walls;
- f) maintenance of vessels by untrained personnel, violation of technological and labor discipline;
- g) violation of the requirements of the Rules due to their ignorance;
- h) extradition officials directives or instructions forcing persons subordinate to them to violate the Rules.
Danger: - the possibility of their destruction during a sudden adiabatic expansion of gases and vapors. i.e. loss of mechanical strength of the walls of the shell (corrosion, local overheating, cracks. (explosions with loss of mechanical strength of vessels, local overheating, impacts, excess working pressure (potential energy - into the kinetic energy of fragments, destroyed equipment and a shock wave (injuries to people. ))) (k-1)/k
Potential energy of the compressed medium: W= *(1-(p1/p2)) K - adiabatic index. P1 and P2 - initial and final pressure, respectively. V - initial volume of gas.
The potential energy of the compressed medium is proportional to the product of the initial pressure and the volume of the vessel: W~PV
- - blast wave (damage to equipment and loss of life.)
- - vessels containing toxic media (risk of poisoning) and flammable media (risk of fire and explosion) are dangerous
Scope of the "rules of design and safe operation":
The rules apply to:
- - vessels operating under the pressure of water with a temperature above 115 C or another liquid with a temperature exceeding the boiling point at a pressure of 0.07 MPa, hydraulic pressure accounting;
- - vessels operating under steam or gas pressure over 0.07 MPa
- - cylinders intended for transportation and storage of compressed, liquefied and dissolved gases under pressure over 0.07 MPa
- - tanks and barrels for transportation and storage liquefied gases, whose vapor pressure at temperatures up to 50C exceeds 0.07 MPa.
- - tanks and vessels for transportation, storage of liquefied gases, liquids and bulk solids, in which pressure over 0.07 MPa is periodically created for emptying;
The rules do not apply to:
- - vessels manufactured in accordance with the "rules for the design and safe operation of equipment and pipelines of nuclear power plants", (Rostekhnadzor), as well as vessels working with a radioactive environment;
- - vessels with a capacity of not more than 25 liters, regardless of pressure, used for scientific and experimental purposes.
- - vessels and cylinders with a capacity of not more than 25 liters, in which the product of MPa pressure and capacity in liters does not exceed 200.
- - vessels working under pressure, creating during the explosion inside them in accordance with the technological process;
- - vessels operating under vacuum;
- - vessels installed on sea, river vessels and other floating facilities;
- - vessels installed on airplanes and other aircraft;
- - air reservoirs for brake equipment of rolling stock of railway transport, cars and other vehicles;
- - vessels special purpose military department;
- -devices of steam and water heating;
- - tube furnaces;
HYDRAULIC AND PNEUMATIC TEST.
Hydraulic test:
All vessels are subject to this test after manufacture (coated and insulated, vessels are tested before insulation and coating are applied);
Uncast vessels: Ppr=1.25r (y20/yf)
Ppr - test pressure; MPa
p - design pressure of the vessel, MPa
y20 - allowable stress of the material of the vessel at 20 C, MPa;
yf - allowable stress of the vessel material at design temperature, MPa
Hydraulic testing of cast vessels and parts is carried out by test pressure, determined by the formula: Ppr \u003d 1.5r (y20 / yf).
Hydraulic testing of vessels and parts not from Me, with a viscosity of more than 20 J/cm2;
Ppr \u003d 1.3r (y20 / yf). If less than 20, then according to Ppr \u003d 1.6r (y20 / yf).
Hydraulic testing of cryogenic vessels in the presence of vacuum in the isolated space of the body is carried out
The procedure for testing should be specified in the technical design and specified in the manufacturer's instructions for the installation and operation of pressure vessels.
For hydraulic testing of vessels, water with a temperature of at least +5C and not higher than +40C should be used. By agreement with the developer of the project, another liquid can be used instead of water. When filling the vessel with water, the air must be completely removed. Hydraulic testing is carried out only after an internal inspection of the vessel. The pressure in the test vessel should be increased gradually. The use of compressed air or gas to raise the pressure is not permitted. The pressure during hydraulic testing is controlled by two pressure gauges of the same type, having the same measurement limits, accuracy class and division value.
The holding time of the vessel under test pressure is set by the project developer. In the absence of special instructions in the project, the exposure time (min) should not be less than:
Wall thickness -50 - 10 min; over 50 - 100mm - 20; over 100mm - 30; for children, multi-layered - 60 min.
After exposure under test pressure, it is reduced to the calculated one and the outer surface is inspected; planing of the walls during the test is not allowed.
The vessel is considered to have passed the test (hydraulic) if there are no cracks, tears, sweating in welded joints, residual deformations, leaks in detachable joints, pressure drop on the pressure gauge. The vessel and its elements - in which defects were identified, after elimination, are subjected to repeated hydration. Trial pressure test. In the case when a hydraulic test is not possible, a pneumatic test is performed (air or inert gas.) (subject to control by the method of acoustic emission).
PNEUMATIC TEST:
(pressure is the same as with hydraulic, careful inspection of the internal state of the vessel, before testing;)
In pneumatic testing, the following precautions apply:
- 1) the valve on the pipeline and pressure gauges are taken out of the room;
- 2) people are removed to a safe distance for the duration of the test; 3) check valve - regardless of pressure fluctuations in front of it, it maintains a constant pressure.
Under test pressure during pneumatic testing, the vessel must be kept for 5 minutes, after which the pressure is gradually reduced to the operating pressure, at which the vessel is inspected with a check of the tightness of its seams and detachable joints with a soap solution or in another way. Tapping of the pressure vessel during the pneumatic test is prohibited. Vessels subject to registration with the Gosgortekhnadzor bodies must be subject to periodic technical examinations by the supervisory engineer of the Kotlonadzor. For the correct design of the vessel, for the calculation of its strength and the choice of material, for the quality of manufacture and installation, as well as for the compliance of the vessel with these Rules, the organization that performed the relevant work is responsible.
All changes in the design during the manufacture or installation of the vessel must be agreed in writing between the design organization that requested the change in the design and Gosgortekhnadzor. If the device has passed the strength test, then it is carried out for tightness.
LEAK TEST:
Pressure vessels harmful substances(liquids and gases) of the 1st and 2nd hazard class according to GOST 12.1.007-76 are tested by the owners of the vessels for tightness with air or inert gas (nitrogen) under pressure,
Equal to working pressure. if the tightness is broken, the equipment breaks - danger (fragments, blast wave, a calculation is made for the strength of the apparatus;)
Upon reaching the test pressure, the supply of compressed air or nitrogen is stopped, a metal plug is placed between the inlet and the pipeline and the shut-off valve and the pressure drop is monitored. (Tests are carried out - 24 hours - new; 4 hours repeated tests). The measurement of the initial pressure and the calculation of the specified time is made after the temperatures inside and outside the vessel have equalized. Measurement of the gas temperature in the vessel should be carried out either by installing mercury thermometers in the sleeves present in the vessel, or by installing thermometers on the surface. The degree of tightness is characterized by the number of gases leaving the apparatus per unit time: m = (Pn-Pk) / Pn f; m- coefficient of tightness (used in determining the amount of harmful substances that have entered the air of industrial premises from equipment, based on this, productivity is determined ventilation unit.); f-time;
pressure drop: Dr= 100/f (1- (Pk Tk/PnTn))
Dr - pressure drop;
Pk ;Pn - final and initial pressure in the apparatus.
Tk, Tn - final and initial temperature in the device.
The tightness is satisfactory if Dr is not more than 0.1% per hour for toxic environments and 0.2% per hour for flammable environments (for new devices). And 0.5% for repeated tests. For devices with P work less than 0.7 atm, Rispyt = P work + 30 kPa. Apparatus for work - not under vacuum tested for strength and tightness:
Strength - 0.2MPa
For tightness - 0.1MPa
GUIDANCE DOCUMENT
VESSELS AND APPARATUS WORKING UNDER PRESSURE
Safety rules and regulations
during hydraulic testing
for strength and tightness
RD 24.200.11-90
Introduction date 01.07.91
Real guidance document establishes safety rules and standards in the preparation and conduct of hydraulic tests for strength and tightness of pressure vessels and apparatus manufactured in accordance with the requirements of OST 26-291, OST 26-01-1183, OST 26-01-900, OST 26- 11-06, OST 26-18-6, OST 26-01-9, OST 26-01-221.
Hydraulic testing of products and their elements for strength and tightness by hydrostatic pressure should be carried out on special test hydraulic stands (hereinafter referred to as hydraulic stands) or, in exceptional cases, on assembly stands using portable equipment.
1. GENERAL PROVISIONS
1.1. The guidance document applies to all methods of hydraulic testing according to OST 26-291 and OST 26-11-14.
1.2. At each enterprise, in accordance with this guidance document, instructions for the safe conduct of hydraulic tests should be developed and approved by the chief engineer. The main provisions of the instruction, as well as the test scheme, must be posted at the workplace of each hydrotest site.
2. REQUIREMENTS FOR PERSONNEL
2.1. To work on hydraulic stands and workplaces with portable equipment for hydraulic testing, workers of the corresponding specialty are allowed according to the Unified Tariff and Qualification Reference Book of Works and Professions of Workers (ETKS), certified in the prescribed manner with a qualification of at least 4 categories.
2.2. The appointment or transfer of a worker is carried out by order in the workshop.
The worker must be familiar with the features of this test equipment and be instructed.
The organization of training and instruction in labor safety must comply with the requirements of GOST 12.0.004.
2.3. Re-testing the knowledge of workers should be carried out at least once a year for workers and once every three years for engineers by a factory qualification commission appointed in the prescribed manner.
2.4. Responsibility for the serviceable condition, correct and safe operation of the hydraulic stand rests with the engineering and technical worker (ITR), appointed by order for the workshop (enterprise) and certified in the prescribed manner.
2.5. Each hydraulic stand in each shift must be assigned to a separate executor by an order for the workshop. The contractor is obliged to monitor the good condition of the hydraulic stand and keep it in proper order and cleanliness. Each hydraulic stand must have a sign indicating the name of the contractor responsible for this hydraulic stand.
2.6. In preparation for hydraulic testing of each product of a new type, design, etc. the work manager must conduct an unscheduled briefing of workers on the features of this product, point out possible sources of danger and precautions.
2.7. To perform work on slinging and moving cargo, controlling lifting mechanisms from the floor, testers must have an appropriate certificate.
2.8. Testers must be provided with overalls and safety shoes of the appropriate size according to standard industry standards for machine-building and metalworking industries.
3. REQUIREMENTS FOR THE SITE, EQUIPMENT, RIGGING
3.1. Requirements for the site and workplace when testing with portable equipment
3.1.1. The site for hydraulic testing must comply with the requirements of the current sanitary standards for the design of industrial enterprises CH118, CH119, CH245, building codes and rules SNiP2, SNiP8, SNiP9.
3.1.2. The area of the site should provide accommodation for:
hydraulic stand (or portable equipment when tested on an assembly stand);
auxiliary equipment and accessories;
of the product under test, taking into account the safe performance of work on its installation and inspection, while the free zone along the perimeter of the maximum possible dimension of the product must be at least 1 m.
3.1.3. The site must have a non-slip floor covering with a slope and (or) holes for water drainage, as well as a protective fence that excludes the possibility of accidental appearance on the site of unauthorized persons and the ingress of working fluid outside the site (Appendix 2).
There should be a light board on the fence with the inscription “NO ENTRY. TESTING IN PROGRESS" or an appropriate poster.
3.1.4. The site must have general and local working lighting, emergency lighting, as well as portable lamps with a voltage of not more than 42 V. Lighting equipment must comply with the requirements of the "Electrical Installation Rules".
Lighting should provide illumination on the surface of the product under test:
working - at least 300 lux with fluorescent or 200 lux with incandescent lighting;
emergency - at least 10 from the working one.
3.1.5. The hydraulic testing site must have a circulating water supply system that ensures filling the volume of the tested products or a technical water supply system with a drain system to the sewer.
3.1.6. The workplace where hydrotesting is carried out with portable equipment must comply with the requirements of paragraphs. 3.1.2 - 3.1.6 of this guidance document.
It is allowed to use a handrail as a temporary protective fence, installed from the tested product at a distance not less than the calculated one (Appendix 3.).
3.2. Requirements for equipment and accessories
3.2.1. The hydraulic stand must be equipped with:
capacity for working fluid with its circulation system;
a pump for filling and emptying the product;
a pump to create pressure in the product;
receiver (buffer tank) or pneumohydroaccumulator;
pipeline system;
stop valves;
instruments for measuring the pressure and temperature of the working fluid;
safety devices or electrocontact manometers (ECM);
plugs.
The electric motors of the pumps must be enclosed, type IP44.
It is allowed to use a pumping unit with a pneumatic drive with a solenoid valve (electric valve) blocking the air supply to the pneumatic drive. The valve must be controlled by an electric contact pressure gauge (ECM) installed in the line from the pump to the product.
When using phosphors, preservatives or other chemicals as part of the working fluid, the hydraulic stand must be additionally equipped with special containers for preparing neutralizing solutions and neutralizing the working fluid and (or) a device for collecting these substances for their further use.
3.2.2. The location and layout of the equipment must meet the requirements of the current building codes and regulations SNiP9, SNiP10 and ensure the safety and convenience of its operation and repair.
The control panel of a hydraulic stand or portable hydrotesting equipment located in a hazardous area determined by the calculation in Appendix 3 must be equipped with protection calculated in accordance with Appendix 2.
3.2.3. When the test product is located underground, a sliding or other mechanical roof should be provided above the buried room, and the area, taking into account the area occupied by the roof in the open position, should have a railing.
3.2.4. The electrical equipment of the hydraulic stand must comply with the requirements of the “Rules for the Arrangement of Electrical Installations”, “Rules for the Technical Operation of Consumer Electrical Installations”, “Safety Rules for the Operation of Consumer Electrical Installations”, as well as building codes and rules SniP6.
3.2.5. The hydrostand must be equipped with "STOP" buttons for emergency stop of the pump motor, painted in red. The number of buttons and their location must ensure that the motor can be stopped quickly.
3.2.6. The rotating parts of the feed pump drive must be securely guarded. Contact of working liquid on the drive is not allowed.
3.2.7. The pressure line of the pump must have a receiver to reduce pressure fluctuations in the product under test caused by the pulsating supply of the working fluid. The receiver must be designed for pressure not lower than the maximum allowable for this hydraulic stand.
The receiver must be installed at the hydrotest site in a place that excludes the presence of people and provides accessibility for its inspection, and has a protective fence designed in accordance with Appendix 2.
It is allowed not to install the receiver and bypass on the hydraulic stands if the pressure in the product under test is reached using a pump without an electric drive (manually).
3.2.8. The location of pipelines should provide free access for inspection and control of their condition.
3.2.9. The pressure measurement should be carried out using two verified pressure gauges, one of which, the control one, should be installed on the product, and the second one - on the control panel of the hydraulic stand.
3.2.10. Manometers for measuring pressure must have the same type, measurement limit, the same division value and an accuracy class of at least:
2.5 at design pressure up to 2.5 MPa (25 kgf / cm 2);
1.5 at a design pressure of more than 2.5 MPa (25 kgf / cm 2) and such a scale on which the measurement limit of the design pressure is in its second third.
3.2.11. The location of the pressure gauges should provide a free view of the pressure gauge scale, while the instrument scale should be in a vertical plane.
The nominal diameter of the case of pressure gauges installed at a height of up to 2 m from the level of the observation site for them must be at least 100 mm, at a height of 2 to 3 m - at least 160 mm. Installation of pressure gauges at a height of more than 3 m from the level of the site is not allowed.
3.2.12. Pressure gauges must be protected from thermal radiation, freezing, mechanical damage.
the absence of a seal or brand with a mark on the verification carried out;
overdue verification period;
malfunctions of the pressure gauge (the pointer does not return to the zero mark of the scale when it is turned off, the glass is broken or there are other damages that may affect the correctness of the readings).
3.2.14. The safety valves of the hydraulic bench must have a capacity corresponding to the performance of the hydraulic pumps, be adjusted to the test pressure, checked for the tightness of the gate and detachable connections and sealed together with a tag indicating the test pressure.
The valves must be adjusted in accordance with GOST 12.2.085. The control medium for determining the valve opening moment can be air or water, which must be clean, without mechanical or chemical impurities.
3.2.15. The installation of safety valves must be carried out in accordance with the "Rules for the Design and Safe Operation of Pressure Vessels" and in accordance with the schematic diagram of the equipment of the hydraulic stand or the schematic diagram approved by the chief engineer of the enterprise.
It is allowed to use electrocontact pressure gauges (ECM) instead of safety valves, while one pressure gauge is installed on the product and one more - in the line from the pump to the product. The connection of the pump with the pressure gauge EKM must be carried out through a buffer tank or a damping device to protect the pressure gauge from the pulsation of the working fluid in the pipeline.
Pressure gauges must be set to the test pressure and ensure that the pump is turned off when the test pressure is reached.
3.2.16. Rubber, metal-rubber hoses and pipelines used in hydraulic testing must have tags indicating their working and test pressure, test period.
The pressure values on the sleeves and pipelines must not be lower than the pressure value for which this hydraulic stand is designed.
Sleeves must comply with current standards or specifications and not have mechanical or chemical damage.
3.2.17. The stop valves of the hydraulic stand must be accessible for maintenance and located no higher than 1.5 m from the floor level. The fittings must be systematically lubricated and scrolled, while the use of any levers is not allowed.
It is not allowed to use fittings that do not have technical documentation (passport, certificate, etc.).
3.2.18. Shut-off valves must be clearly marked:
manufacturer's name or trademark;
conditional pass, mm;
conditional pressure, MPa (kgf / cm 2);
medium flow direction;
material grade.
3.2.19. The marking of the plugs used for hydrotesting should indicate the number of the plug and the pressure value for which it is designed.
3.2.20. The product under test must have:
valve or cock to control the absence of pressure in it before dismantling it. It is allowed to use a three-way valve installed on the product. The outlet of the tap must be directed to a safe place. It is allowed not to install a valve or tap if there are couplings for draining the liquid.
safety valves, the number and throughput of which must exclude the possibility of a pressure exceeding the test pressure in the product. It is allowed to use safety valves with a rupture disc designed for test pressure.
It is allowed not to install safety valves on the product if they are provided in the line between the pump and the tested product and are designed for test pressure.
3.2.21. The working fluid leaving the safety valve must be drained to a safe place. The installation of locking devices on the outlet pipes, as well as between the product and the safety valve is not allowed.
3.2.22. Working fluids used for hydraulic testing must be non-toxic, non-explosive, non-flammable.
It is allowed, at the request of the product developer, to use other liquids with the obligatory observance of the relevant safety measures.
3.2.23. The structures of service platforms and ladders to them (scaffolding) must comply with the current "Safety regulations for construction and installation works" and "General safety regulations and industrial sanitation for enterprises and organizations of mechanical engineering".
3.2.24. Cranes and mechanisms used at the hydraulic testing site must comply with the requirements of the current "Rules for the Construction and Safe Operation of Cranes".
3.2.25. The hydraulic stand and all assembly units, units and devices included in it must have certificates or passports. The use of technological equipment that does not have technical documentation and (or) with mechanical damage to the threaded, sealing, seating surfaces, signs of stretching, is not allowed.
3.2.26. The hydraulic stand must be certified in accordance with GOST 24555 and accepted by the commission appointed by the order for the enterprise.
Certification documentation is developed by the stand developer and agreed with the metrological service of the enterprise before certification of the hydro stand.
Testing of the hydraulic stand must be carried out with a pressure equal to 1.25 of the pressure for which the hydraulic stand is designed.
Technical documentation must be attached to the certificate for the hydraulic stand:
attestation protocol (Appendix 1);
calculations of the elements of the stand for strength;
passports and certificates for devices, units and fittings used at the stand;
safety instructions for working on the hydraulic stand;
order to appoint a person responsible for the hydraulic stand.
3.2.27. The technical documentation for the hydraulic stand must be kept by the person responsible for its good condition and safe operation (see clause 2.4).
3.2.28. The hydrostand must be registered with the metrological and technical service of the enterprise, which carries out scheduled preventive repairs.
3.2.29. The hydrostand must be periodically, once every 6 months, subject to inspection and at least once a year - repair.
Scheduled preventive repairs must be carried out in strict accordance with the schedule approved by the chief engineer of the enterprise. After repair, the hydraulic stand must be subjected to a hydraulic pressure test in accordance with clause 3.2.27 and certified in accordance with GOST 24555.
3.2.30. Verification of pressure gauges with their sealing or branding should be carried out at least once a year in the prescribed manner.
Additional verification of working pressure gauges with a control one should be carried out at least once every 6 months with the results recorded in a journal. It is allowed to use a certified working pressure gauge for verification of working pressure gauges, which has the same scale and accuracy class with the verified one. Regardless of the indicated terms, the verification of pressure gauges must be carried out if there is any doubt about the correctness of their readings.
3.2.31. Checking of safety valves should be carried out at least once a year, within the time limits established by the management of the enterprise. Checking, repairing and adjusting the safety valve must be documented by an act signed by the workshop mechanic, the repair and adjustment foreman and the locksmith who carried out these works.
The safety valve that has been repaired and adjusted must be sealed together with a tag indicating the test pressure and provided with a number.
Each safety valve must have a technical passport, along with which copies of the passports for the valve and spring from the supplying factories, as well as copies of the certificates of its verification, repair and adjustment, must be kept.
3.2.32. Rubber, metal-rubber hoses and pipelines must be checked and tested at least once a year according to the preventive maintenance schedule. Tests must be carried out in accordance with the relevant regulatory and technical documents for these products and building codes and regulations.
3.2.33. Shut-off valves after each repair must be tested for mechanical strength and tightness with hydraulic pressure that meets the requirements of the regulatory and technical documentation for this valve, but not lower than the maximum pressure for which the hydraulic bench is designed. The test of shut-off valves must be formalized by an act.
Tests should be carried out after fitting and fitter-machining.
4. SAFETY REGULATIONS FOR HYDRAULIC TESTING
4.1. Preparation for hydraulic testing
4.1.1. Products and their elements subject to hydrotesting must be accepted by the quality control department based on the results of an external examination and non-destructive testing.
The value of the test pressure for the product must not exceed the maximum allowable pressure for which the hydraulic stand is designed.
4.1.2. Fasteners and seals used in hydrotesting must be made of materials provided for in the working drawings for the product.
4.1.3. Instrumentation, safety devices, fittings, plugs, fasteners, gaskets, etc. must be selected according to the marking for a pressure not lower than the test one.
4.1.4. When installing the product under test on the hydraulic stand on standard or technological supports, its stable position, free access for inspection and the location of drainage holes (“air vents”) at its upper point must be ensured.
The hydraulic testing scheme, the technological process and equipment must ensure complete removal of air when filling the product under test with a working fluid.
4.1.5. Installation of communications, installation of the required fittings, instrumentation must be carried out in full accordance with the approved hydraulic testing scheme.
All free openings of the product under test shall be plugged.
Installation, equipment and inspection of the product at a height of more than 1.5 m should be carried out from special sites (scaffolding).
4.1.6. When mounting flanged connections, the threaded elements must be tightened evenly, alternately tightening diametrically opposite ("crosswise"), while maintaining the parallelism of the flanges.
Do not use wrenches that do not match the size of the nut, non-standard and / or with a handle extension, as well as a hammer or sledgehammer.
4.1.7. When preparing a working fluid using phosphors, preservatives, as well as when applying indicator coatings to the controlled surfaces of the tested product, a system of general exchange supply and exhaust ventilation must be switched on in the hydrotesting area.
4.2. Carrying out hydraulic tests
4.2.1. A minimum number of people, but not less than two people, should participate in hydraulic testing.
4.2.2. During hydrotesting it is prohibited:
be on the territory of the site to persons not participating in the test;
be from the side of the plugs to the persons participating in the test;
carry out extraneous work on the territory of the hydraulic testing site and work related to the elimination of detected defects on a product under pressure. Repair work may only be carried out after the pressure has been relieved and, if necessary, the operating fluid has been drained.
transport (turn over) a product under pressure;
transport loads over a pressurized product.
4.2.3. The tester is prohibited from:
to carry out tests on a hydraulic stand that is not assigned to him or his team by order in the workshop;
leave without supervision the control panel of the hydraulic stand, the product under test connected to the water supply system (even after the pressure has been removed);
perform under pressure assembly and disassembly of products, equipment, repair of equipment of the hydraulic stand, etc.;
to arbitrarily make changes to the technological process of testing, change the pressure or holding time under pressure, etc.
4.2.4. Hydraulic testing on an assembly stand using portable equipment is allowed in exceptional cases with the written permission of the chief engineer of the enterprise and compliance with the requirements of this guideline.
4.2.5. The product under test must be completely filled with the working fluid, the presence of air cushions in communications and the product is not allowed.
The surface of the product must be dry.
4.2.6. The pressure in the product should rise and fall smoothly. The increase in pressure should be carried out with stops (for the timely detection of possible defects). The value of the intermediate pressure is taken equal to half of the test pressure. The rate of pressure rise should not exceed 0.5 MPa (5 kgf / cm 2) per minute.
The maximum deviation of the test pressure should not exceed ± 5% of its value. The exposure time of the product under test pressure is set by the project developer or indicated in the regulatory and technical documentation for the product.
4.2.7. It is forbidden to be near and (or) inspect the product during the increase in pressure to the test pressure and holding the product under test pressure. The personnel participating in the test must be at the control panel at this time.
Inspection of the product should be carried out after the pressure in the product is reduced to the calculated one.
At the design pressure in the product, it is allowed to be at the hydraulic stand:
testers;
defectoscopists;
representatives of the technical control department (TCD);
responsible for the safe conduct of work - foreman, senior foreman, head of the site;
heads of departments;
employees of leading technical departments;
customer representatives.
These persons must undergo special training or appropriate instruction in accordance with GOST 12.0.004.
4.2.8. When using flaw detection equipment with sources of ultraviolet radiation, exposure of the eyes and skin of workers is not allowed.
4.2.9. The tester is obliged to interrupt the test, turn off the pumps that create pressure, or shut off the valves of the pipelines supplying pressure to the product (when using one pump for several workplaces) and open the pressure relief valves when:
interruption in the supply of working pressure;
reaching a pressure in the product or pipelines higher than permitted despite compliance with all the requirements specified in the instructions;
failure of pressure gauges or other indicating instruments during pressure rise;
actuation of safety devices;
the occurrence of water hammer in the pipeline or product, the appearance of vibration;
detection of leaks, cracks, bulges or sweating in welds in the tested product, technological equipment, pipelines;
leakage through the drainage holes, which serves as a signal to terminate the test;
destruction of the tested product;
fire, etc.
4.2.10. After depressurizing the system, before disassembling the flange connections, it is necessary to remove the working fluid from the product and the system.
4.2.11. When dismantling the tooling, the nuts of the bolted connections should be removed, gradually loosening the diametrically opposite ones (“crosswise”), and pay attention to the integrity of the sealing elements in order to prevent them from falling into the internal cavities of the product.
4.2.12. Waste working fluid containing chemicals must be neutralized and (or) cleaned before being discharged into the sewer network.
Discharge into the sewer of working liquids containing phosphors, preservatives, etc., which have not undergone neutralization and (or) purification, is prohibited.
When working with a solution of bleach at the site of hydrotesting, the system of general exchange supply and exhaust ventilation must be turned on. The exhaust pipe of the ventilation system must be located directly above the container with the bleach solution.
Chlorine lime that has fallen on the floor should be washed off with water into the sewer drain.
All work with bleach should be carried out in goggles, a canvas suit, rubber boots and gloves, with a gas mask on.
4.2.13. Removal from the skin of phosphors based on fluorescein and its solutions (suspensions) must be done with soap and water or 1 - 3% aqueous solution ammonia.
Upon completion of work with phosphors, personnel must thoroughly wash their hands with warm water and soap.
PROTOCOL OF APPROVALS
1. CHARACTERISTICS OF THE HYDROSTAND Design pressure, MPa (kgf / cm 2) ____________________________________________ Permissible working pressure, MPa (kgf / cm 2) __________________________________ Design temperature, °C _________________________________________________ Characteristics of the working agent ______________________________________________ (water, neutral liquids, etc.) ___________________________________________ 2. LIST OF INSTALLED UNITS 3. LIST OF INSTALLED FITTINGS AND MEASURING INSTRUMENTS 4. INFORMATION ABOUT CHANGES IN THE STAND DESIGN 6. INFORMATION ABOUT PERSONS RESPONSIBLE FOR THE STAND 7. MARKS ON THE PERIODIC SURVEYS OF THE BENCH PRINCIPAL DIAGRAM OF THE HYDROSTAND ACT OF MANUFACTURING HYDROSTAND Company ___________________ Manufacturing shop _______________ Stand for hydraulic testing in accordance with the drawing No. ___________________________ and TU _____________________________ and accepted by the Quality Control Department of shop No. ________________ Beginning manufacturer's shop ____________________________________________ (stamp) (signature) Master _________________________________________________________________ (signature) Control master ______________________________________________ (stamp) (signature) |
WELDING DETAILS
Welding performed by welder ______________________________________________
Full Name
Welder's certificate No. _________________ issued by ________________________
ACT OF TESTING
(name of the node, pipeline, incoming
__________________________________________________________________________
to the hydraulic stand) (drawing, code, Inv. No.)
for strength (tightness) with liquid (air) under pressure ____________ MPa (kgf / cm 2) with exposure for _____________ minutes.
The tests were carried out in accordance with _______________________________________
passed the test
(name of the pipeline unit)
Beginning manufacturing workshop __________________
(signature)
Control Master ___________________
(signature)
APPENDIX 2
Reference
Copy
Institute of Hydrodynamics
Siberian Branch of the Academy of Sciences of the USSR
APPROVE
Deputy Director of the Institute
hydrodynamics SB AS USSR
corresponding member USSR Academy of Sciences
B.V. Voitsekhovsky
V.V. Mitrofanov
Method for calculating protection against liquid
jets formed during the rupture of blood vessels
high pressure
Novosibirsk, 1965
1. INTRODUCTION
Modern technology makes extensive use of various tanks, pipelines, etc., filled with high-pressure liquid. These containers are usually designed with a sufficiently large margin of safety and their accidental rupture is unlikely. However, in some cases, the margin of safety has to be made small, and then special armor protection has to be provided for the service personnel and equipment, which would protect against liquid jets, and, possibly, metal fragments formed during a sudden rupture of the vessel. This raises the problem of calculating the required thickness of protective armor.
This issue is especially acute when designing benches for testing various containers with liquid (usually water) at high pressure, since during such tests the vessel walls are often subjected to loads close to the elastic limit.
2. ON THE MECHANISM OF INTERACTION OF A WATER JET WITH A BARRIER. RELATIONSHIP BETWEEN THE JET PARAMETERS AND THE THICKNESS OF THE METAL SHEET REQUIRED FOR PROTECTION
Let a jet of water with a density? 1 , speed u and diameter d hits an obstacle in the form of a metal sheet with a density? 2 and thick? perpendicular to its surface. Let us consider the interaction of a jet with an obstacle under limiting conditions, i.e. we will assume that the thickness is just such that the sheet at the point of impact of the jet receives a dent, but does not tear. The interaction is divided into two stages: 1) the initial process of flow formation on the barrier surface, when increased shock pressures act on the barrier for a short time; 2) a quasi-stationary process of interaction that occupies all subsequent time, when the pressure of the jet on the barrier is determined by the Bernoulli equation.
Let's consider these stages of the process separately.
2nd stage. The total pressure force of the jet on the barrier is equal to the pressure at the stagnation point on the axis of the jet; therefore, the diameter of the high-pressure region close to P T, on the surface of the obstacle will be approximately . It follows from geometrical considerations that the radius of curvature of the surface streamlines in the region of their rotation is close to . Equating the centrifugal pressure of the surface layer of the jet, which has a velocity close to U, pressure near the stagnation point, we obtain for the thickness of this layer a value of the order of . After that, it is easy to estimate the volume of liquid in the vicinity of the stagnation point, which has a pressure close to P T and low speed it turns out to be okay
Since, due to the low compressibility of water, the elastic energy of the liquid in the indicated volume is negligible, the quantity gives us the energy lost by the jet upon impact.
Further. Let us calculate the tensile forces at the bottom of the dent in the 2nd stage. Assuming that the surface of the dent is spherical and the barrier material on the entire surface of the dent stretches uniformly up to the maximum allowable relative elongation?, it is easy to obtain a formula relating the radius of curvature of the dent surface R with its diameter d vm And?:
(1)
The diameter of the dent should be close to the diameter of the high pressure area, i.e.
Solutions to equation (1), in which (2) is substituted for a number of values, are given in Table 1
Table 1
R/ d |
See what for? > 0.1, which corresponds to structural metals, R/d weakly depends on?, so in what follows we will assume
R ? d. (3)
Given that?/ R << 1, что, как будет видно из дальнейшего, при давлении до нескольких сотен атмосфер достаточно хорошо выполняется, стенку вмятины можно считать тонкостенной, а растягивающее напряжение s в ней рассчитывать по формуле:
Obviously, s should not exceed the equivalent breaking stress in biaxial tension:
Combining formulas (3 - 5), we obtain the condition that the wall can withstand the pressure of a steady jet in the form:
Now it is required to find out whether the protection calculated by formula (6) will withstand the impact of the jet in the 1st stage.
Before the moment of impact, all fluid particles move perpendicular to the barrier surface with a velocity U. After the collision, the lateral surface of the jet near the barrier acquires the same velocity U in the perpendicular direction as a result of the action of a lateral rarefaction wave on the liquid compressed by the shock wave. Increased pressures act on the barrier up to a circle with a diameter of about 2 d, since by this moment the distribution of velocities in the jet in the vicinity of the impact point will approach the distribution in the case of a stationary flow.
This process consumes a segment of the jet with a length of about which has a mass ~ momentum ~ and energy ~ Note that the estimate of the volume and energy of this segment of the jet gives the same value that was previously obtained in another way for the volume and energy loss of the stagnant fluid in a steady flow. The specified energy value corresponds to the maximum amount of energy that the wall can receive in the process of flow establishment, i.e. in the 1st stage.
However, the actual energy transfer depends on the ratio (the process of collision of the head of the jet with the wall is somewhat similar to the inelastic collision of balls). From the conservation laws, we easily obtain the expression:
(7)
Where E- energy transferred to the protective sheet
k- the ratio of the area of the sheet, perceiving the impulse to the cross-sectional area of the jet.
If we write now that E should not exceed the energy of the allowable deformation of the sheet in the area of the dent, the area of which we will designate until then through then we obtain the condition of non-penetration of the sheet in stage 1:
Let us resolve this inequality with respect to ?, first replacing and setting , which corresponds to the values k And k 1 close to real, we will have:
(8)
Formulas (6) and (8) give the same values? at
(9)
At P T > P*T more important? gives formula (6), with P T < P*T - formula (7). Therefore, depending on the value P T one formula or another must be applied. If a sheet from Art 3 is used as a barrier, then
P*T\u003d 200 kg / cm 2. (9 *)
3. APPROXIMATE CALCULATION OF THE JET OUTLET
Since it is not known in advance what shape and dimensions the hole in the vessel wall will have in the event of its rupture, when calculating the protection, it is obviously necessary to focus on the worst case, when a hole is formed that gives a jet of maximum penetrating power.
The exact solution of the problem of the outflow presents considerable difficulties, but here it is possible to make estimates that are quite sufficient for calculating the protection.
Let us have a vessel with a volume Vc liquid under pressure P 1 . The excess volume of liquid that must be released from it so that the pressure drops to atmospheric is denoted by D V 1 . Let at t 1 = 0 a hole with an area S and characteristic size (for example, diameter) d.
The rarefaction wave moving away from the free surface into the vessel reduces the pressure near the surface to atmospheric pressure and imparts a speed to the surface layer of the liquid where c= speed of sound in liquid.
Although we are dealing here with a three-dimensional fluid flow, the characteristic acceleration time of the fluid is t* can be estimated according to a one-dimensional scheme: a rarefaction wave due to a sharp expansion of the front surface when entering inside the vessel at a distance of about d from the hole is reflected back in the form of a compression wave of the same amplitude (just as when a rarefaction wave passes in a pipe through the region of a sharp increase in the cross section).
In this case, in the cross section of the hole, the fluid velocity increases by the same value D U. The compression wave is again reflected from the free surface by a rarefaction wave, which increases the speed by another D U etc. Since the fluid velocity in the hole cross section increases by a value over time , the average increment of the jet velocity per unit time at the beginning of the outflow will be
The characteristic jet acceleration time will be:
(10)
To take into account the influence of pressure changes in the vessel during the outflow, we will apply a different approach: we will calculate the outflow as for an incompressible liquid (this is justified, for now), and we will take into account the compressibility only through the relationship between the pressure in the vessel and the amount of the leaked liquid. Along the axis of the hole, the fluid velocity U depends on one coordinate X and time t.
We write the pressure equation along this axis:
We integrate it over x, assuming
Where V"(t) - speed in the hole section;
K 2 \u003d 1 - numerical coefficient, since with distance from the hole deep into the liquid, the velocity decreases very quickly, approximately.
After integration, we get:
(11)
Where P(t) is the pressure in the vessel, which changes during the outflow. Note that this equation implies the law of the increase in speed in the initial stage of the process, that is, when P ? P 1 and coinciding with the previous one.
Up to pressures of several hundred atmospheres, we can assume that the pressure in the vessel is linearly related to the excess volume of liquid D V 1 currently contained in the vessel. Therefore, we can write:
Introducing the last expression into equation (11) and passing to dimensionless variables: , where U? And t* take from (10), we get the equation:
1/3 V 2 max
Here lmax- jet length at the moment t = t max, When V = Vmax.
4. PRACTICAL CALCULATION OF PROTECTION
Although in reality the shape of the resulting hole is almost never round in case of a sudden rupture of the vessel, it is necessary to calculate for a round hole in such a way that it can be shown that it is the round hole that poses the greatest danger.
Expressing in formulas (6) and (8) d through? And P T through P 1:
P T= V 2 P 1 , (14)
using expressions (13) and (14) we obtain:
(15)
(16)
Since for everyone P 1 value Vmax depends on ?, then it is necessary to choose a value ? at which the right-hand sides of inequalities (15) and (16) will reach the maximum value.
Formula (15) includes the product V 2 ? 1/3, from the above table we see that the maximum of this product is reached at? = 0.3 and close to 0.5. Substituting this value into (15) to determine the thickness of the protection, we obtain:
(17)
at so how at? = 0.3, Vmax = 0,7, R * T is taken from formula (9).
For St 3 formula (17) is applicable at P 1 > 300 kgf / cm 2.
For P 1 < 300 кгс/см 2 нужно использовать формулу (16). Ее применение осложняется тем, что?, соответствующее максимальному значению правой части, зависит от P 1 , so for each P 1 it is necessary by selection to find such a ? that gives the maximum of the right side of the inequality. At the same time appropriate for everyone? values V 2 are taken from the table.
However, the calculation can be greatly simplified if we use the original equation (8), in which d And P T can be expressed in terms of the initial parameters D V 1 and P 1 for physical reasons. Indeed, when deriving formula (8), we proceed from the momentum and energy carried by the head of the jet with a length of about d/2. It is obvious that this energy and momentum will be the greatest if the head part carries the elastic energy of the vessel with liquid, equal to , and the entire excess mass, equal to? 1D V 1 , i.e., if we have, in fact, not even a jet, but a lump of liquid, which has approximately the same dimensions in all directions.
Then instead of (8) we get:
(18)
In the resulting expressions, it is necessary to add another margin of safety, not less than 2.5.
In conclusion, we write out the final formulas for calculating the thickness of the protection from St 3 with a safety factor of 4, assuming s T\u003d 2700 kgf / cm 2, s V\u003d 3500 kgf / cm 2, , ? = 0.2.
For P 1 > 300 kgf / cm 2 (19)
For P 1 < 300 кгс/см 2 (20)
Where P 1 - in kgf / cm 2, D V 1 - in cm 3,? - in cm
Calculation D V for spherical and cylindrical vessels, it is not difficult if the elastic properties of the vessel shell and the compressibility of the liquid are known. For example, for water in a spherical vessel:
(21)
Where R- vessel radius;
1 - vessel wall thickness;
Young's modulus;
µ - Poisson's ratio.
APPENDIX 3
Reference
DETERMINING THE SAFE DISTANCE TO NON-PARTICIPANT PERSONNEL
IN HYDRAULIC TESTING
The energy of a compressed fluid can be determined by the formula:
Where P- pressure at which the product collapsed (hydrotest pressure);
D V- additional volume of liquid pumped into the product with a volume Vc without considering its deformation.
D V = V about - V s,
Where V about is the total volume of the liquid subjected to compression;
V s- the volume of the vessel,
V s= a V about.
Hence:
(2)
where a is the total compression modulus.
The value a can be determined by the formula:
Where A And B- constant coefficients selected from the table depending on the fluid used and the test temperature.
The total energy of the gas in the vessel ( E), in kgm, can be determined by the formula:
Where K= 1.4 - adiabatic index for air.
To compress 1 m 3 of air to pressure P\u003d 10 kgf / cm 2 at a constant temperature, work is required ( E), in kgm:
Therefore, the volume of an air cylinder that is equivalent in terms of stored energy to a test product with a compressed liquid can be determined by the formula, in m 3:
The excess pressure at the front of the air shock wave at the rupture of an equivalent cylinder, depending on the distance, can be determined by the empirical formula, in kgf / cm 2:
(6)
where is a dimensionless quantity;
r- distance from the center of the product to the considered point, m;
E szh- the energy of compression of the liquid in the product, equal to the energy of compression of the gas in an equivalent cylinder, kgm;
P a- atmospheric pressure, kgf/cm 2 .
Formula (Sec. 6.3) is valid for r > r p,
Where r p- distance from which the shock wave propagation law is described by the theory for a point source of explosion, m,
Where Q = ?V b- mass of gas in the vessel, kg;
? - gas density, kg/m 3 ;
V b- vessel volume, m 3 .
When calculating the safety distance r it should be borne in mind that the maximum overpressure at the front of the air wave at the point under consideration should not exceed 0.1 kgf / cm 2. Taking into account that the effect of product destruction during hydrotesting in some cases (due to uneven wave propagation) can be more significant than the effect of destruction of an equivalent cylinder, we consider it necessary to multiply the safe distance obtained by the above method by a factor of 1.5.
The distance obtained in this way will be the minimum, closer than which personnel not participating in the hydrotesting should not be located.
INFORMATION DATA
1. DEVELOPED AND INTRODUCED
All-Union Scientific Research and Design Institute of Technology of Chemical and Petroleum Apparatus (VNIIPTkhimnefteapparatura)
DEVELOPERS:
V.P. Novikov (topic leader); N.K. Lamina; A.M. Eremin
2. APPROVED AND INTRODUCED by the order of the Ministry of Heavy Machine Building dated 25.07.90 No. VA-002-7259
3. REGISTERED by NIIkhimmash
for no. RD 24.200.11-90 from 06/19/1990
4. Information about the timing and frequency of document verification:
The term of the first inspection is 1992, the frequency of inspection is 2 years
5. INTRODUCED FOR THE FIRST TIME
6. REFERENCE REGULATIONS AND TECHNICAL DOCUMENTS
Number of paragraph, subparagraph, enumeration, application |
|
GOST 12.0.004-79 |
|
GOST 12.2.085-82 |
|
GOST 24555-81 |
|
OST 26-01-9-80 |
Introduction |
OST 26-01-221-80 |
Introduction |
OST 26-01-900-79 |
Introduction |
OST 26-01-1183-82 |
Introduction |
OST 26-11-06-86 |
Introduction |
OST 26-11-14-88 |
|
OST 26-18-6-80 |
Introduction |
OST 26-291-87 |
1. General provisions. 1 2. Requirements for personnel. 1 3. Requirements for the site, equipment, rigging. 2 3.1. Requirements for the site and workplace when testing with portable equipment .. 2 3.2. Requirements for equipment and accessories. 3 |
Carrying out a hydraulic test. Order of conduct. Test pressure .
A hydraulic test to check the density and strength of pressure equipment, as well as all welded and other joints, is carried out:
a) after installation (additional production) at the installation site of equipment transported to the installation (additional production) site in separate parts, elements or blocks;
b) after reconstruction (modernization), repair of equipment using welding of pressure elements;
c) during technical surveys and technical diagnostics in the cases established by these FNP.
Hydraulic testing of individual parts, elements or blocks of equipment at the place of installation (additional manufacturing) is not mandatory if they have passed a hydraulic test at their places of manufacture or have been subjected to 100% control by ultrasound or other equivalent non-destructive method of flaw detection.
It is allowed to conduct a hydraulic test of individual and prefabricated elements together with the equipment, if under the conditions of installation (additional manufacturing) it is impossible to test them separately from the equipment.
Hydraulic testing of equipment and its elements is carried out after all types of control, as well as after the elimination of detected defects.
The minimum value of the test pressure P pr. During a hydraulic test for steam and hot water boilers, superheaters, economizers, as well as for pipelines within the boiler, is taken:
a) at a working pressure of not more than 0.5 MPa - 1.5 working pressure, but not less than 0.2 MPa;
b) at working pressure over 0.5 MPa - 1.25 working pressure, but not less than working pressure plus 0.3 MPa.
172. The value of test pressure during hydraulic testing of metal vessels (with the exception of cast ones), as well as electric boilers, is determined by the formula:
, (1)
where P is design pressure in case of additional production at the place of operation, in other cases - working pressure, MPa ;
, - allowable stresses for the material of the vessel(electric boiler) or its elements, respectively, at 20 °C and design temperature, MPa.
The ratio of materials of assembly units (elements) of the vessel (electric boiler) operating under pressure is taken according to the used materials of the elements (shells, bottoms, flanges, nozzles, etc.) of the vessel, for which it is the smallest, with the exception of bolts (studs), as well as heat exchange tubes of shell-and-tube heat exchangers.
The test pressure when testing a vessel calculated by zones should be determined taking into account the zone, the design pressure or design temperature of which is less important.
The test pressure for testing a vessel designed to operate in several modes with different design parameters (pressures and temperatures) should be taken equal to the maximum of the determined test pressure values for each mode.
The value of test pressure during hydraulic testing of cast and forged vessels is determined by the formula
. (2)
It is allowed to test castings after assembly and welding in an assembled unit or a finished vessel with a test pressure accepted for vessels, subject to 100% control of castings by non-destructive methods.
Water should be used for hydraulic pressure testing of equipment. The water temperature should not be lower than 5 °C and not higher than 40 °C, unless the equipment manufacturer's technical documentation specifies a specific temperature value that is allowed under the conditions for preventing brittle fracture.
The water used for hydraulic testing must not contaminate the equipment or cause severe corrosion.
The temperature difference between the metal and the ambient air during the hydraulic test should not lead to moisture condensation on the surface of the equipment walls.
In technically substantiated cases provided by the manufacturer, it is allowed to use another liquid when conducting a hydraulic test during the operation of vessels.
180. When filling equipment with water, air must be completely removed from it.
The pressure in the equipment under test should be raised smoothly and evenly. The total pressure rise time (up to the test value) must be indicated in the technological documentation. Water pressure during hydraulic testing should be controlled by at least two pressure gauges. Both pressure gauges choose the same type, measurement limit, the same accuracy classes (not lower than 1.5) and divisions.
The use of compressed air or other gas to pressurize equipment filled with water is not permitted.
The exposure time under test pressure for steam and hot water boilers, including electric boilers, steam and hot water pipelines, as well as vessels assembled at the installation site, is set by the manufacturer in the operating manual and must be at least 10 minutes.
The exposure time under test pressure of vessels of element-by-element block supply, additionally manufactured during installation at the place of operation, must be at least:
a) 30 min. with vessel wall thickness up to 50 mm;
b) 60 min. with a vessel wall thickness over 50 to 100 mm;
c) 120 min. with vessel wall thickness over 100 mm.