Devices and safety of operation of technological pipelines. Industrial safety requirements for the operation of technological pipelines chapter general provisions

21.08.202327.05.2017

Food industry enterprises use pipelines for various purposes: for steam, hot water, flammable and caustic liquids (alcohols, acids, alkalis). The most common are steam and hot water pipelines, the operation of which is regulated by the Rules for the Design and Safe Operation of Steam and Hot Water Pipelines.
Depending on the operating parameters, these pipelines are divided into 4 categories (Table 9).
Table 9
Categories of steam and hot water pipelines

Category	Wednesday	Working environment parameters
Category	Wednesday	Temperature, "C	Pressure, MPa
1	superheated steam	>580	Not limited
	» *	540...580
		450...540	¦ »
	» »	<450	>3.9
	Hot water, saturated steam	<115	>8.0
2	superheated steam	350...450	<3.9
		<350	2,2...3,9
	Hot water, saturated steam	>115	3,9...8,0
3	superheated steam	250...350	<2,2
	»3gt;	<250	1,6...2,2
	Hot water, saturated steam	>115	1,6...3,9
4	superheated steam	115...250	0,07...1,6
	1" "	>115	<1.6

At food production enterprises, pipelines of the 3rd and 4th categories are operated for steam with a temperature of not more than 350 ° C and a pressure of less than 2.2 MPa, for hot water - with a temperature of more than 115 ° C and a pressure of less than 1.6 MPa, and for sugar enterprises use steam pipelines of the 1st and 2nd categories. Thus, these, as well as other pipelines under pressure and intended for the transportation of flammable and toxic gases, flammable and toxic liquids, are objects of increased danger, requiring special supervision and control over their design, construction and operation.
Compared to pipelines for other purposes, steam and hot water pipelines operate in more difficult conditions, since in addition to the influence of their own mass and the mass of the working media contained in them, the fittings installed on them, they are under the influence of higher internal pressure, the mass of thermal insulation and thermal alternating stresses . The combined effect on pipelines that are simultaneously under tensile, bending, compression and torsion stresses necessitates a thorough justification of their mechanical strength and design, corresponding to the purpose of the pipeline and the operating parameters of the medium contained in it, in order to ensure safety during operation.
The main causes of accidents in pipelines for various purposes, including steam and hot water: defects in pipelines; errors made during the design process when choosing materials, schemes and pipeline structures, taking into account the properties of the transported medium; insufficient assessment of compensation for thermal elongation of pipelines; deviation from projects during construction and installation works; violation of the operation mode of pipelines, including untimely and poor-quality repairs, overflows, damage to pipelines, leakage of stuffing boxes, erroneous actions of maintenance personnel; hydraulic shocks; violation of the rules for filling and emptying pipelines with combustible gases; accumulation of static electricity; untimely and poor-quality technical examination of pipelines, instrumentation, safety devices, shut-off and control valves.
The safe operation of pipelines is ensured by special measures. These measures can be divided into 3 groups.
Design and construction measures include: selection of a rational scheme of the pipeline and its design; carrying out calculations of the pipeline for strength and compensation for thermal elongations; substantiation of operating parameters, materials, method of laying the piping system and drainage system, placement of supports, stop valves, etc.
The layout of pipelines, their placement and design, in addition to observing technological requirements, should ensure safe operation, the possibility of direct observation of the technical condition of the pipeline, accessibility for technical examination and testing, installation and repair work, ease of maintenance of control and measuring equipment, safety devices, shut-off and control fittings. This provides for: installation of horizontal sections of steam pipelines with a slope of at least 0.002 ° and a drainage device; installation of shut-off valves in the direction of movement of the medium, and at the lower points of each section switched off by the valves - a pipeline of drain (drainage) fittings with shut-off valves for emptying the pipeline, at the upper points of air vents for air removal. Saturated steam lines and dead ends of superheated steam lines must be equipped with steam traps or other devices for the continuous removal of condensate to prevent destructive water hammer.
Pipelines of combustible and toxic gases are equipped with fittings with locking devices for filling the pipeline with an inert gas, which ensures the safety of the process of filling it with a working medium and emptying it.
Pipelines for acids and alkalis must have a slope for draining and an air purge device. The choice of materials is of particular importance for the pipelines of flammable and corrosive liquids. In this case, mechanically fragile materials (glass, polyethylene, etc.) must not be used, and for flammable liquids - materials that do not conduct current, in order to avoid the accumulation of static electricity and increase the risk of explosion. For this purpose, pipelines of flammable liquids must be grounded.
All welded joints on pipelines for various purposes are controlled. At the same time, they carry out: external examination, ultrasonic flaw detection, transillumination, mechanical and hydraulic tests, metallographic examination. On pipelines of caustic liquids, instead of welded joints, as an exception, it is allowed to use flange connections for attaching fittings to pipelines or them to equipment nozzles. These connections on pipelines transporting acids and alkalis are equipped with special protective casings, which exclude the possibility of aggressive liquids entering the room.
In order to simplify and shorten the term for determining the purpose of the pipeline, to eliminate erroneous actions when disconnecting or switching individual lines or sections of pipelines, to facilitate the management of production processes, as well as to ensure safety, a certain identification color has been established for pipelines for various purposes. The colors of the identification coloring of pipelines transporting various substances are given in Table. 10.
Table 1 0
Identification painting of pipelines

Pipelines with the most dangerous substances in terms of their properties are marked with warning color rings in addition to the identification color. Their number and color depend on the degree of danger and the operating parameters of the transported substance. Rings on pipelines transporting flammable, dangerous and explosive substances are painted red; dangerous and harmful - in yellow, and safe and neutral - in green. With an increase in the danger of a substance and the magnitude of its operating parameters, the number of rings changes from 1 to 3. For example, on pipelines of saturated steam and hot water with a pressure of 0.1 ... 1.6 MPa and a temperature of 120 ... 250 ° C, one ring is applied , and with a pressure of more than 18.4 MPa and a temperature of more than

120°C - three. The width of the warning rings and the distance between them depend on the outer diameter of the pipelines.
Organizational measures include registration of pipelines, their periodic technical examination, strength and density tests, training, certification of maintenance personnel and systematic testing of their knowledge, maintenance of technical documentation and other organizational measures to ensure the safe operation of pipelines and their repair.
Before commissioning, pipelines for various purposes are subjected to technical examination and registration with Rostekhnadzor bodies or at enterprises that own the pipeline. A permit for the operation of pipelines subject to registration with the bodies of Rostekhnadzor is issued by an inspector of Rostekhnadzor after registering, and for unregistered pipelines - an employee of the enterprise responsible for their good condition and safe operation, based on the verification of the documentation and the results of his survey. The permit is registered in the pipeline passport. The same person issues a permit for the commissioning of pipelines, both registered and not registered with the Rostekhnadzor authorities, with a corresponding entry in the pipeline shift log.
Technical examination of steam and hot water pipelines is carried out by the administration of the enterprise within the following terms: external examination - at least once a year; external inspection and hydraulic testing of pipelines that are not subject to registration with Rostekhnadzor bodies - before commissioning after installation associated with welding, repair, and also start-up after conservation of the pipeline for more than 2 years.
Pipelines registered with the local authorities of Rostechnadzor, in addition to surveys conducted by the administration of the enterprise, are subject to survey by a Rostechnadzor inspector in the presence of a person responsible for the good condition and safe operation of pipelines, within the following periods: external inspection - at least once every 3 years; external inspection and hydraulic test - before the start-up of the newly installed pipeline, as well as after repair with welding and start-up after conservation for more than 2 years.
Pipelines of combustible and toxic gases after installation are subjected to external inspection and testing for strength and density. The types and modes of testing are specified in the pipeline project, and the frequency is determined by the schedule approved by the chief engineer of the enterprise. Additional tests for tightness by working pressure are also carried out after each repair of the pipeline. Technical examination and testing of pipelines of flammable and corrosive liquids for strength and density are carried out in accordance with building codes and regulations.
Technical examination of pipelines, which provides for their external inspection and hydraulic testing, on newly installed steam and hot water pipelines is carried out before thermal insulation is applied. The purpose of the external inspection is to check the serviceability and compliance of the installed pipeline with the Rules for Pipelines and the documents submitted during its registration. During the inspection, special attention is paid to the possibility of free movement of the pipeline with its temperature elongation, the correct location of movable and fixed supports, the presence and location of compensators, benchmarks and drainage devices provided for by the project.
During external inspection of operated pipelines, the following is checked: the condition of rigid and spring suspensions of the pipeline, movable supports; compliance of the location of air drainage with the Rules for pipelines; the presence of check valves on the supply pipelines; compliance of the number and location of shut-off devices, as well as their parameters, with the Rules for pipelines; the presence of protective covers on flange connections; compliance of coloring, warning rings and inscriptions on pipelines with the requirements of standards; compliance of inscriptions on valves, gate valves and actuators with the Rules for pipelines; the presence of plates on the pipelines indicating the registration number, permitted pressure, medium temperature and the date (month, year) of the next inspection.
Hydraulic tests are carried out in order to check the strength and density of all elements and pipeline connections. During hydraulic testing of steam and hot water pipelines, in order to avoid brittle fractures of the metal, the water temperature should not be lower than 5 ° C, and for steam pipelines operating at a pressure of 10 MPa or more, the temperature of their walls should not fall below + 10 ° C. Hydraulic testing of pipelines is carried out, as a rule, at positive ambient temperature. Pipelines, their blocks and individual elements are subjected to a hydraulic test with a test pressure equal to 1.25 working pressure, and fittings and fittings - with a test pressure provided for by the standard. Vessels that are an integral part of the pipeline are tested with the same pressure as the pipelines.
The test pressure is maintained for 5 minutes, after which it is reduced to the working one and the pipeline is carefully inspected.
The results of the hydraulic test are considered satisfactory if there was no pressure drop on the pressure gauge, and no signs of rupture, leakage and fogging were found in the welds, pipes, valve bodies and other equipment.
Tests for the strength and density of pipelines of combustible and toxic gases or their individual sections are carried out by employees of the enterprise. In this case, the pipeline or its section is disconnected on both sides from other pipelines or fittings using plugs. To disconnect the pipeline or its section from the rest of the system, shut-off equipment must not be used. The location of the plugs installed for the duration of the test is marked with warning signs. The pressure in the pipeline and the test procedure are set in accordance with the recommendations of the design organization specified in the pipeline project.
Persons at least 21 years of age who have undergone a medical examination, trained in the relevant program, have a certificate from the qualification commission for the right to maintain pipelines and know the production instructions are allowed to service pipelines for various purposes. At least once every 12 months, they must pass a knowledge test with registration in the prescribed manner for passing exams.
Each pipeline must have: a passport, a diagram indicating fittings and equipment, and for combustible and toxic gases, flammable and caustic liquids, in addition, indicating all flange connections and welds; shift and repair logs, pipeline testing schedule and other documentation.

Control measures are carried out using control and measuring equipment, safety devices, shut-off and control valves, which must be located on pipelines, in places accessible for maintenance, equipped with platforms, stairs or have remote control. In rooms where pipelines of combustible and toxic gases, flammable and corrosive liquids are located, diagrams of the pipeline system should be posted indicating the location of all devices, instruments, fittings and connections.
Repair work of pipelines included in their system of channels and chambers and other equipment is carried out in accordance with the instructions for the operation and repair of pipelines approved by the chief engineer of the enterprise. Repair work is carried out only if there is a work permit issued by the administration of the enterprise - the owner of the pipeline. The composition of the brigade for carrying out repair work must meet certain requirements, its members must have certificates for carrying out the necessary repair work, undergo current safety briefing.
The person responsible for the good condition and safe operation of pipelines enters information about the repair work performed, which does not necessitate an early technical examination of the pipeline, in its repair log. Information related to the need for an extraordinary technical examination of the pipeline, as well as data on the materials and quality of welding used during the repair, is entered in the pipeline passport.

2.2.5. Seamless pipes made from ingots, as well as fittings from these pipes, are allowed to be used for pipelines of groups A and B of the first and second categories, provided that they are controlled by ultrasonic flaw detection (USD) in a volume of 100% over the entire surface.

2.2.18. For pipelines transporting substances of groups A and B of technological facilities of explosion category I, it is not allowed to use flange connections with a smooth sealing surface, except for the cases of using spiral wound gaskets.

Fasteners

2.2.19. Fasteners for flange connections and materials for them should be selected depending on the operating conditions and the steel grade of the flange according to.

To connect flanges at temperatures above 300 °C and below minus 40 °C, regardless of pressure, studs should be used.

2.2.20. In the manufacture of studs, bolts and nuts, the hardness of studs or bolts must be higher than the hardness of nuts by at least 10-15 HB.

2.2.21. The materials used for the manufacture of fasteners, as well as fasteners entering the warehouse, must have a manufacturer's certificate.

In the absence of a certificate for the material, the manufacturer of fasteners must certify materials based on the results of determining their physical and mechanical characteristics (including chemical composition) according to existing standards or specifications and draw up a certificate.

2.2.22. It is not allowed to manufacture fasteners from boiling, semi-calm, Bessemer and automatic steels.

2.2.23. The material of blanks or finished fasteners made of high-quality carbon, as well as heat-resistant and heat-resistant alloy steels, must be heat treated.

For fasteners used at pressures up to 1.6 MPa (16 kgf / cm 2) and operating temperatures up to 200 ° C, as well as fasteners made of carbon steel with threads up to 48 mm in diameter, heat treatment is not required.

2.2.24. In the case of using fasteners made of austenitic steels at a working temperature of the medium above 500 ° C, it is not allowed to produce a thread by knurling.

It is allowed to use materials of fasteners and flanges with coefficients of linear expansion, the values of which differ by more than 10%, in cases justified by strength calculations or experimental studies, as well as for flange connections at an operating temperature of the medium of not more than 100 °C.

Gasket materials

Shaped parts of pipelines

2.2.27. Fittings of pipelines, depending on the parameters of the transported medium and operating conditions, should be selected according to the current NTD standards, norms, specifications, as well as according to the technical documentation of the project developer.

For pipelines of technological facilities of category I of explosion hazard, transporting substances of groups A and B, it is prohibited to use fittings manufactured with deviations from the current NTD.

2.2.28. Fittings of pipelines must be made of steel seamless and longitudinally welded pipes or sheet metal, the metal of which meets the requirements of the project, regulatory and technical documents, as well as the conditions of weldability with the material of the pipes to be connected.

2.2.29. Parts of pipelines for environments that cause corrosion cracking of metal, regardless of design, steel grade and manufacturing technology, are subject to heat treatment.

Local heat treatment of welded joints of sectional branches and tees welded from pipes is allowed if heat-treated pipes are used for their manufacture.

Welded parts

2.2.30. When choosing welded parts of pipelines, depending on the aggressiveness of the medium, temperature and pressure, these Rules and other applicable regulatory documents should be followed.

2.2.31. Welding of fittings and quality control of welded joints should be carried out in accordance with the requirements of the current NTD.

2.2.32. A branch from the pipeline can be made in one of the ways shown in fig. , or in accordance with OST 36-45-81, OST 36-41-81 and the drawings of the project developer. When installing tee connections, special attention should be paid to the quality of fitting and welding work. Reinforcement of tee connections with stiffeners is not allowed.

3.1.4. In pipelines intended for operation under pressure up to 35 MPa (350 kgf / cm 2), it is allowed to weld fittings in straight sections, as well as the use of tees welded from pipes, stamp-welded elbows with two longitudinal seams, subject to 100% control of welded joints by ultrasonic flaw detection or transillumination.

3.1.5. Welding of fittings into welds, as well as into bent elements (in places of bends) of pipelines is not allowed.

As an exception, on bends of pipelines operating under pressure up to 35 MPa (350 kgf / cm 2), welding of one fitting (pipe) for a measuring device with an inner diameter of not more than 25 mm can be allowed.

3.1.6. To connect pipeline elements made of high-strength steels with a tensile strength of 650 MPa (6500 kgf / cm 2) or more, only threaded coupling or flange connections should be used. Welded joints of such steels may be allowed in exceptional cases. Welding technology and quality control of such joints must be agreed with a specialized research organization.

3.1.7. Removable sections of insulation shall be provided at the locations of the most stressed welded joints and measurement points of residual deformation accumulated during metal creep.

3.2. Pipeline design requirements

Forged and stamped parts

3.2.1. Parts of high-pressure pipelines must be made from forgings, forgings and pipes. It is allowed to use other types of blanks if, according to the conclusion of a specialized research organization, they provide reliable operation during the estimated service life, taking into account the specified operating conditions.

3.2.2. The ratio of the inner diameter of the branch to the inner diameter of the main pipe in forged tee inserts should not be less than 0.25. If the ratio of nozzle diameter to main pipe diameter is less than 0.25, tees or nozzles must be used.

Bent and welded elements

3.2.3. The design and geometric dimensions of tees welded from pipes, stamped rings, bent bends and fittings must meet the requirements of standards, specifications and drawings.

3.2.4. Tees welded from pipes, stamped-welded bends, tees and bends from blanks cast using electroslag technology can be used for pressures up to 35 MPa (350 kgf / cm 2). In this case, all welds and metal of cast billets are subject to 100% ultrasonic testing.

3.2.5. The ratio of the inner diameter of the fitting (branch) to the inner diameter of the main pipe in welded tees should not exceed 0.7.

3.2.6. The use of bends welded from sectors is not allowed.

3.2.7. Bent bends after bending must be subjected to heat treatment. The heat treatment mode is set by standards, specifications, drawings.

3.2.8. Branches bent from steel grades 20, 15GS, 14KhGS after cold bending can only be tempered, provided that before cold bending the pipes were quenched with tempering or normalized.

Detachable connections and fasteners

3.2.9. For detachable connections, threaded flanges and butt-welded flanges must be used, taking into account the requirements of clauses of these Rules.

3.2.10. As sealing elements of flange connections, metal gaskets should be used - lenses of flat, octagonal, oval and other sections.

3.2.11. Thread on pipeline parts, threaded flanges, couplings and fasteners must be made according to,. The shape of the cavities of the external threads must be rounded. Thread tolerances - 6H, 6g By . The quality of the thread must ensure the free passage of the thread gauge.

3.2.12. In the case of the manufacture of fasteners by cold deformation, they must be subjected to heat treatment - tempering. Thread rolling on austenitic steel studs for operation at temperatures above 500 °C is not allowed.

Welds and their location

3.2.13. The design and location of welded joints must ensure their high-quality performance and control by all the methods provided for in the process of manufacture, installation, operation and repair.

In any case, the specified distance should allow local heat treatment and weld inspection by non-destructive methods.

Welded joints of pipelines must be located from the edge of the support at a distance of 50 mm for pipes with a diameter of less than 50 mm and at least 200 mm for pipes with a diameter of more than 50 mm.

For pipes with an outer diameter of 100 mm or more, this distance must be at least 100 mm.

3.2.16. If it is impossible to ensure the distance specified in paragraphs. and , the issue in each case is decided by a specialized research organization or the author of the project.

3.3. Requirements for materials used for high pressure pipelines

3.3.1. For the manufacture, installation and repair of steel pipelines for pressures over 10 MPa (100 kgf / cm 2) up to 320 MPa (3200 kgf / cm 2) and temperatures from minus 50 to plus 540 ° C, materials and semi-finished products must be used according to state standards and technical the conditions specified in the table. 3.6.

9.1. Supervision and maintenance

9.1.1. The administration of the enterprise - the owner of pipelines is obliged to maintain them in accordance with the requirements of these Rules, as well as other applicable inter-industry and departmental norms and rules, ensuring the safety of service and reliability of work.

Operation, supervision, revision and repair of pipelines must be carried out in accordance with the instructions developed on the basis of these Rules.

9.1.2. Persons who supervise pipelines at the enterprise, as well as persons responsible for the good condition and safe operation of pipelines, should be appointed by order of the enterprise from among the engineers who have the appropriate qualifications and practical experience, who have been certified in accordance with the "Regulations on the procedure for testing knowledge rules, norms and safety instructions for executives and specialists of enterprises, organizations and facilities controlled by the Gosgortekhnadzor of Russia.

The number of responsible persons for the implementation of supervision should be determined based on the calculation of the time required for the timely and high-quality performance of the duties assigned to these persons by official position.

9.1.3. For each installation (shop, production), the person responsible for the safe operation of pipelines must draw up a list of pipelines, made in two copies: one is kept by the person responsible for the safe operation of pipelines, the other - in the technical supervision service by the person supervising pipelines.

9.1.4. For all high-pressure pipelines [over 10 MPa (100 kgf/cm)] and low-pressure pipelines [up to 10 MPa (100 kgf/cm) inclusive] of categories I, II, III, as well as pipelines of all categories transporting substances at a corrosion rate pipeline metal 0.5 mm / year, the administration of the enterprise must draw up a passport of the established sample (Appendix 3).

The list of documents attached to the passport must comply with the requirements of section 9.4.

9.1.5. The passport for the pipeline must be kept by the person responsible for the safe operation of pipelines.

9.1.6. For pipelines that are not subject to the requirements of clause 9.1.4, it is necessary to keep an operating log at each installation, in which the dates of the audits carried out and data on the repairs of these pipelines should be entered.

9.1.7. Technological pipelines operating in hydrogen-containing media must be periodically inspected in order to assess the technical condition in accordance with the current regulatory and technical documents.

9.1.8. The maintenance of technological pipelines can be entrusted to persons who have reached the age of 18, trained according to a program developed in accordance with the requirements of these Rules and other NTD for pipelines, who know their scheme and have passed the knowledge test on safety regulations.

9.1.9. Persons supervising high-pressure pipelines should keep a record book of periodic testing of the pipeline.

9.1.10. On pipelines made of carbon and silicon-manganese steel with a working temperature of 400°C and above, as well as pipelines made of chromium-molybdenum (working temperature 500°C and above) and high-alloy austenitic steel (working temperature 550°C and above), monitoring of the growth of residual deformations. Observation, control measurements and cuttings are made in accordance with the instructions developed by the owner of the pipeline on the basis of the "Standard Instructions for Monitoring and Extending the Service Life of the Metal of the Main Elements of Boilers, Turbines and Pipelines of Thermal Power Plants. RD 34.17.421-92" and agreed with the specialized scientific research organization.

9.2. Supervision during operation

9.2.1. During the operation of pipelines, one of the main duties of maintenance personnel is constant and careful monitoring of the condition of the outer surface of pipelines and their parts (welds, flange joints, including fasteners, fittings), corrosion protection and insulation, drainage devices, compensators, supporting structures, etc. .d. The results of inspections should be recorded in the logbook at least once per shift.

9.2.2. Supervision of the correct operation of pipelines is carried out daily by the person responsible for the safe operation of pipelines, periodically - by the technical supervision service together with the management of the workshop and the person responsible for the safe operation of pipelines, at least once a year.

9.2.3. During a periodic inspection, it is necessary to check:

technical condition of pipelines by external inspection and, if necessary, non-destructive testing in places of increased corrosion and erosion wear, loaded sections, etc.;

elimination of comments on the previous inspection and implementation of measures for the safe operation of pipelines, provided for by the instructions of the state technical supervision bodies and the technical supervision service of the enterprise, orders and instructions, accident investigation reports and protocols of technical meetings;

completeness and procedure for maintaining technical documentation for the operation and repair of pipelines.

The results of the periodic inspection of pipelines are documented in an act, one copy of which is transferred to the head of the workshop of the owner of the pipeline.

9.2.4. Pipelines subject to vibration, as well as foundations under supports and overpasses for these pipelines during the operation period, must be carefully inspected using instrumental control over the amplitude and frequency of vibration by the technical supervision service together with the administration of the shop (production) and the person responsible for the safe operation of pipelines.

Defects found in this case must be immediately eliminated.

The timing of inspections, depending on the specific conditions and condition of the pipelines, is established by the technical administration of the enterprise, but at least once every 3 months.

The maximum allowable vibration amplitude of technological pipelines is 0.2 mm at a vibration frequency of not more than 40 Hz.

9.2.5. External inspection of pipelines laid in an open way, during periodic inspections, can be carried out without removing the insulation. However, if the condition of the walls or welds of the pipelines is in doubt, then at the direction of the person supervising the operation of the pipelines, partial or complete removal of insulation should be carried out.

9.2.6. External inspection of pipelines laid in impassable channels or in the ground should be carried out by opening in separate sections with a length of at least 2 m. The number of sections, depending on the operating conditions, is established by the person responsible for safe operation.

9.2.7. If, during external inspection, leaks in detachable joints are found, the pressure in the pipeline must be reduced to atmospheric pressure, the temperature of hot pipelines must be up to plus 60 ° C, and the defects must be eliminated in compliance with the necessary safety measures.

If defects are found, the elimination of which is associated with hot work, the pipeline must be stopped, prepared for repair work in accordance with applicable instructions, and the defects eliminated.

The person responsible for the safe operation of pipelines is responsible for the timely elimination of defects.

9.2.8. During the external examination, the condition should be checked:

insulation and coatings;

welded seams;

flange and coupling connections, fasteners and devices for installing instrumentation;

supports;

compensating devices;

drainage devices;

reinforcement and its seals;

benchmarks for measuring residual deformation;

welded tee joints, bends and bends.

At the same time, the vibration of the pipeline is checked.

9.3. Pipeline revision

9.3.1. The main method of monitoring the reliable and safe operation of technological pipelines is a periodic audit, which is carried out by the technical supervision service together with mechanics, heads of installations (productions).

The results of the audit serve as the basis for assessing the condition of the pipeline and the possibility of its further operation.

9.3.2. As a rule, the revision of pipelines should be timed to the scheduled preventive maintenance of individual units, installations or workshops.

9.3.3. The timing of the inspection of pipelines at pressures up to 10 MPa (100 kgf / cm) is set by the administration of the enterprise, depending on the rate of corrosion and erosion wear of pipelines, operating experience, the results of the previous external inspection, revision. The terms should ensure safe, trouble-free operation of the pipeline in the period between revisions and should not be less than those indicated in Table. 9.1.

Table 9.1

Periodicity of revisions of process pipelines with pressure up to 10 MPa (100 kgf/cm)

Transported media		Inspection frequency at corrosion rate, mm/year
		over 0.5	0,1 - 0,5	up to 0.1

Extremely, highly and moderately hazardous substances of classes 1, 2, 3 according to GOST 12.1.007-76 and high-temperature organic heat transfer fluids (HOT) (group A media)	I and II	At least once a year
Explosive and flammable substances (HE), combustible gases (GH), including liquefied, flammable liquids (flammable liquids) in accordance with GOST 12.1.007-76 [environments of group B (a), B (b)]	I and II	At least once a year	At least once every 2 years	At least once every 3 years
		At least once a year	At least once every 3 years
Combustible liquids (CL) in accordance with GOST 12.1.004-76 [environments of group B (c)]	I and II	At least once a year	At least once every 2 years	At least once every 3 years
	III and IV	At least once a year	At least once every 3 years	At least once every 4 years
Slow-burning (TG) and non-combustible (NG) substances according to GOST 12.1.004-76 (Group B media)	I and II	At least once every 2 years	At least once every 4 years	At least once every 6 years
	III, IV and V	At least once every 3 years	At least once every 6 years	At least once every 8 years

9.3.4. For high pressure pipelines [over 10 MPa (100 kgf / cm )], the following types of revision are established: selective, general selective and complete. The timing of the selective audit is set by the administration of the enterprise, depending on the operating conditions, but at least once every 4 years.

The first selective revision of pipelines transporting non-aggressive or slightly aggressive media must be carried out no later than 2 years after the pipeline is put into operation.

9.3.5. Postponement in the audit of pipelines in case of operational need is determined by the administration of the enterprise, taking into account the results of the previous audit and the technical condition of the pipelines, ensuring their further reliable operation, and is issued in writing for a period of not more than one year.

9.3.6. When conducting an audit, special attention should be paid to areas operating in particularly difficult conditions, where the maximum wear of the pipeline due to corrosion, erosion, vibration and other reasons is most likely. These include areas where the direction of flow changes (elbows, tees, tie-ins, drainage devices, as well as sections of pipelines before and after fittings) and where accumulation of moisture, substances that cause corrosion is possible (dead ends and temporarily inoperative sections).

9.3.7. An audit should be started only after the necessary preparatory work has been completed, provided for by the current instructions for the organization and safe performance of repair work.

9.3.8. When inspecting pipelines with pressures up to 10 MPa (100 kgf/cm), it is necessary:

a) conduct an external inspection of the pipeline in accordance with the requirements of clause 9.2.8;

b) measure the thickness of the pipeline wall with non-destructive testing devices, and, if necessary, by through drilling with subsequent welding of the hole.

The number of sections for thickness measurement and the number of measurement points for each section is determined by the person supervising the operation of pipelines, together with the person responsible for the safe operation of pipelines.

The wall thickness is measured in areas operating in the most difficult conditions (elbows, tees, tie-ins, places of narrowing of the pipeline, before and after fittings, places of accumulation of moisture and products that cause corrosion, stagnant zones, drainages), as well as in straight sections of intra-installation, intrashop and intershop pipelines.

At the same time, on straight sections of intra-installation pipelines with a length of 20 m or less and inter-workshop pipelines with a length of 100 m or less, wall thickness measurements must be performed at least in three places.

In all cases, the wall thickness control in each place should be carried out at 3 - 4 points along the perimeter, and on bends - at least 4 - 6 points along the convex and concave parts.

It is necessary to ensure the correctness and accuracy of measurements, to exclude the influence of foreign bodies on them (burrs, coke, corrosion products, etc.), and also to check measuring instruments and devices in a timely manner.

The measurement results are recorded in the pipeline passport.

Notes. 1. An audit of permanent sections of flare lines that do not have bypasses is carried out without turning them off by measuring the wall thickness with ultrasonic thickness gauges and washing the flange connections.

2. The issue of partial or complete removal of insulation during the inspection of pipelines is decided by the person supervising the operation of pipelines.

3. On pipelines made of austenitic grade steels (08X18H10T, 12X18H10T, etc.) operating in media that cause intergranular corrosion, through drilling is not allowed.

c) inspect flange collars by internal inspection (when disassembling the pipeline) or by measuring the thickness by non-destructive testing methods (ultrasonic or radiographic) at least at three points around the circumference of the flange collar. The wall thickness of the flange collar can also be controlled by means of control drillings. The number of flanges subject to revision is determined by the person supervising the operation of pipelines, depending on the operating conditions;

d) conduct an internal inspection of the pipeline section using a lamp, an RVP-type device, a magnifying glass, an endoscope or other means, if as a result of measuring the wall thickness and tapping the pipeline there are doubts about its condition; In this case, the inner surface must be cleaned of dirt and deposits, and, if necessary, pickled. In this case, you should choose a site operated in the most unfavorable conditions (where corrosion and erosion, water hammer, vibration, change in flow direction, stagnant zones are possible). The dismantling of a pipeline section in the presence of detachable connections is carried out by disassembling them, and this section is cut out on an all-welded pipeline.

During the inspection, check for corrosion, cracks, reduction in wall thickness of pipes and pipeline parts;

e) carry out radiographic or ultrasonic inspection of welded joints, if their quality during the audit raised doubts; if necessary, these welded joints should be subjected to metallographic and mechanical tests. The number of joints to be checked is determined by the person supervising the operation of pipelines;

f) check the mechanical properties of the metal of pipes operating at high temperatures and in hydrogen-containing media, if this is provided for by the current regulatory and technical documents or project. The mechanical properties of the metal should also be checked in cases where the corrosive action of the medium can cause them to change. The issue of mechanical testing is decided by the technical supervision service of the enterprise;

g) measure the deformation on the pipeline sections as of the time of the audit in accordance with the requirements of clause 9.1.10 and check the documentation for recording creep observations;

h) disassemble (optionally, at the direction of the representative of technical supervision) threaded connections on the pipeline, inspect them and measure them with thread gauges;

i) check the condition and correct operation of supports, fasteners and, optionally, gaskets;

j) test the pipeline in accordance with these Rules.

9.3.9. If the inspection results are unsatisfactory, it is necessary to determine the boundary of the defective section of the pipeline (inspect the inner surface, measure the thickness, etc.) and perform more frequent measurements of the wall thickness of the entire pipeline at the discretion of the technical supervision representatives.

9.3.10. The volume of selective revision of high pressure pipelines [over 10 MPa (100 kgf/cm)] should be:

at least two sections of each unit of the installation, regardless of temperature;

at least one section of each general workshop collector or inter-shop pipeline, regardless of the temperature of the medium.

The unit is understood as a group of devices and machines connected by piping and designed to carry out a certain part of the technological process (for example, a gas separation unit, a compressor unit, etc.).

A collector is a pipeline that connects a number of units operating in parallel.

9.3.11. The selection of sites for revision is made by the person responsible for the good condition and safe operation of pipelines, together with the technical supervision service. When choosing, you should identify areas operating in the most severe conditions, where wear is most likely to occur due to corrosion, erosion, vibration and other causes. When choosing a site, the results of the previous external examination and previous revisions should be taken into account.

9.3.12. When inspecting the control section of the high-pressure pipeline, it is necessary:

a) conduct an external examination in accordance with the requirements of clause 9.2.8;

b) if there are flange or socket connections, disassemble them, then inspect the pipeline internally;

c) to measure the thickness of the walls of pipes and other parts of the control section with non-destructive testing devices;

d) if defects are found in the welds (near-weld zone) during the inspection or if there are doubts about their quality, carry out control by non-destructive methods (radiographic, ultrasonic, etc.);

e) if there are doubts about the quality of the metal, check its mechanical properties and chemical composition. The verification method is determined by the technical supervision service;

f) check the condition of couplings, flanges, their mating surfaces and threads, gaskets, fasteners, as well as fittings and fittings, if any, in the control area;

h) carry out control for residual deformation in accordance with the requirements of clause 9.1.10, if it is provided for by the project;

g) to control the hardness of fasteners of flange joints operating at a temperature of 400°C.

9.3.13. The results of the audit are considered satisfactory if the detected deviations are within acceptable limits.

In case of unsatisfactory audit results, two more similar sections should be checked, of which one should be a continuation of the audited section, and the second - similar to the audited section.

9.3.14. If, on inspection of the high pressure pipeline, it is found that the original thickness has been reduced by corrosion or erosion, the operability must be confirmed by a strength calculation.

9.3.15. Upon receipt of unsatisfactory results of the audit of additional sections, a general selective audit of this pipeline, as well as sections of pipelines operating in similar conditions, with dismantling of up to 30% of each of these pipelines or less, with an appropriate technical justification issued by a specialized organization, should be carried out.

9.3.16. A general selective audit of high-pressure pipelines should also be carried out periodically at the following times:

a) in the production of ammonia:

pipelines intended for transportation of nitrogen-hydrogen and other hydrogen-containing gas mixtures at an ambient temperature of up to 200 ° C - after 24 years, at an ambient temperature of over 200 ° C - after 8 years;

b) in methanol production:

pipelines intended for the transportation of hydrogen gas mixtures containing, in addition to hydrogen, carbon monoxide, at an ambient temperature of up to 200 ° C - after 15 years, at an ambient temperature of more than 200 ° C - after 6 years;

c) in the production of caprolactam:

pipelines intended for transportation of hydrogen gas mixtures at ambient temperatures up to 200°C - after 10 years, pipelines intended for transportation of carbon monoxide at temperatures above 150°C - after 8 years;

d) in the production of synthetic fatty alcohols (SFA):

pipelines intended for transportation of hydrogen gas mixtures at ambient temperatures up to 200°C - after 10 years, at ambient temperatures above 200°C - after 8 years;

pipelines intended for transportation of paste (catalyst with methyl esters) at ambient temperatures up to 200°C - after 3 years;

e) in the production of urea:

pipelines intended for transporting the urea melt from the synthesis column to the throttling valve - after 1 year;

pipelines intended for transportation of ammonia from the heater to the mixer at an ambient temperature of up to 200°C - after 18 years;

pipelines designed to transport carbon dioxide from the compressor to the mixer at an ambient temperature of up to 200 ° C - after 6 years;

pipelines intended for transportation of carbon ammonium salts (carbamate) at ambient temperatures up to 200 ° C - after 4 years.

A general selective audit of pipelines intended for the transportation of other liquid and gaseous media and other industries should also be carried out:

at a corrosion rate of up to 0.1 mm/year and a temperature of up to 200°C - after 10 years;

the same at a temperature of 200 - 400 ° C - after 8 years;

for environments with a corrosion rate of up to 0.65 mm/year and an ambient temperature of up to 400°C - after 6 years.

In case of unsatisfactory results of the general selective audit, the administration of the enterprise appoints a full audit of the pipeline.

9.3.17. With a complete audit, the entire pipeline is completely disassembled, the condition of the pipes and parts, as well as the fittings installed on the pipeline, is checked. The terms and obligatoriness of a complete audit of pipelines are not regulated by these Rules and are determined by the bodies and persons exercising supervision, or by the administration of the enterprise, if the need for it is confirmed by the results of a general selective audit.

9.3.18. All pipelines and their sections subjected to disassembly, cutting and welding during the audit, after assembly, are subject to a strength and density test.

For pipelines with P10 MPa (100 kgf/cm) when disassembling single flange connections associated with the replacement of gaskets, fittings or individual elements (tee, coil, etc.), it is allowed to test only for density. In this case, the newly installed fittings or pipeline element must first be tested for strength by test pressure.

9.3.19. After the audit, acts are drawn up, to which all the protocols and conclusions on the studies carried out are attached. The audit results are recorded in the pipeline passport. Acts and other documents are attached to the passport.

9.3.20. After the expiration of the design service life, the pipeline must be subjected to a comprehensive survey in order to establish the possibility and period of further operation in accordance with the requirements of these Rules and the current industry NTD.

Maintenance and revision of fittings

9.3.21. The fittings of technological pipelines are the most important element of communications, therefore, the necessary measures must be taken at enterprises to organize constant and thorough supervision of the serviceability of fittings, as well as timely and high-quality inspection and repair.

When using fittings with stuffing boxes, special attention should be paid to the stuffing material - quality, dimensions, correct installation in the stuffing box.

Stuffing for glands is selected in accordance with GOST 5152.

9.3.22. Asbestos packing, impregnated with a fatty composition and graphed, can be used for operating temperatures not higher than 200 ° C, since with higher heating, fatty substances flow out and the density of the stuffing box quickly decreases.

9.3.23. For temperatures above 200°C and pressures up to 25 MPa (250 kgf/cm2), it is possible to use asbestos-programmed packing. In addition, each ring must be sprinkled with a layer of dry clean graphite with a thickness of at least 1 mm.

9.3.25. For pressures above 32 MPa (320 kgf/cm) and temperatures above 200°C, the use of special packings in accordance with clause 9.3.24 is mandatory.

9.3.26. The stuffing box packing of the fittings must be made of a braided cord of square section with a side equal to the width of the stuffing box. From such a cord on a mandrel, blanks of rings with ends beveled at an angle of 45 ° should be cut.

9.3.27. The packing rings should be placed in the stuffing box opposite the cut lines with the seal of each ring. The height of the stuffing box packing should be such that the grundbox in the initial position enters the stuffing box no more than 1/6 - 1/7 of its height, but not less than 5 mm.

The glands should be tightened evenly without distortion of the gland box.

9.3.28. To ensure the tightness of the gland seal, it is necessary to monitor the cleanliness of the surface of the spindle and stem.

9.3.29. The gasket material for sealing the connection between the cover and the valve body should be selected taking into account the chemical effect of the transported medium on it, as well as depending on pressure and temperature in accordance with clause 2.2.26 of these Rules.

9.3.30. The spindle stroke in gate valves and valves must be smooth, and the valve must move without jamming when closing or opening valves.

9.3.31. Relief valves must be serviced in accordance with industry and manufacturer's guidelines.

9.3.32. To create tightness, the shut-off valves should be closed with normal force. It is not allowed to use additional levers when opening and closing valves.

9.3.33. Revision and repair of pipeline fittings, including non-return valves, as well as drive devices of fittings (electric, pneumatic, hydraulic, mechanical drive), as a rule, are carried out during the revision of the pipeline.

9.3.34. Revision and repair of fittings should be carried out in specialized workshops or at repair sites. In some cases, at the discretion of technical supervision, it is allowed to revise the fittings by disassembling and inspecting them directly at the installation site (welded fittings, large-sized, hard-to-reach, etc.).

9.3.35. When inspecting fittings, including check valves, the following work must be performed:

a) external examination;

b) disassembly and inspection of the condition of individual parts;

c) inspection of the internal surface and, if necessary, control by non-destructive methods;

d) lapping of sealing surfaces;

e) assembly, testing and pressure testing for strength and density.

9.3.36. When planning the revision and repair of valves, it is necessary first of all to carry out the revision and repair of valves operating in the most difficult conditions, while observing the principle of alternation. The results of repair and testing of fittings are documented in an act.

Control drilling

9.3.37. In cases where the nature and pattern of corrosion wear of the pipeline cannot be established by the control methods used in the audit, it is allowed to perform control drilling for timely signaling that the wall thickness is approaching the rejection size.

The need for control drilling is determined by the technical supervision service of the enterprise for each specific case, taking into account the restrictions set forth in paragraph 9.3.38.

9.3.38. Pipelines transporting substances of groups A (a), A (b), gases of all groups, pipelines operating under vacuum and high pressure [over 10 MPa (100 kgf / cm )], pipelines in blocks of explosion category I, as well as pipelines made of steels of type 18-8 and operating in environments that cause intergranular corrosion are not subjected to control drilling. In these cases, control over the condition of the pipeline wall thickness should be strengthened by measuring with an ultrasonic thickness gauge or by using through drilling.

9.3.39. When pilot holes are drilled, use a 2.5 - 5 mm diameter drill set at a sharp angle to prevent large product leaks in case of missing pilot holes.

9.3.40. Holes for control drilling should be located in places of turns, narrowings, tie-ins, stagnant zones, as well as in tees, drainage outlets, before and after shut-off valves, etc.

9.3.41. Control drilling holes on bends and half-bends should be located mainly along the outer radius of the bend at the rate of one hole per 0.2 m of length, but not less than one hole per bend or welded bend section.

9.3.42. The depth of control drilling should be equal to the calculated thickness plus PxS (where P is half the period between successive revisions, year, C is the actual corrosion rate of the pipeline, mm / year).

9.3.43. Pilot drilling locations on the pipeline must be clearly marked.

9.3.44. The passage of a control hole on the pipeline indicates the approach of the wall thickness to the rejection size, therefore, such a pipeline must be subjected to an extraordinary revision.

Periodic testing of pipelines

9.3.45. The reliability of pipelines is checked by periodic tests for strength and density in accordance with the requirements of Section 8 of these Rules.

When testing for strength and density, it is allowed to use acoustic emission control.

9.3.46. The frequency of testing pipelines for strength and density is timed to the time of the audit of the pipeline.

The timing of the test for pipelines with pressures up to 10 MPa (100 kgf / cm) should be equal to twice the frequency of the audit, adopted in accordance with the requirements of clause 9.3.3 for this pipeline, but at least once every 8 years.

The timing of the test for pipelines with pressures over 10 MPa (100 kgf / cm) should be (at least):

for pipelines with temperatures up to 200°C - once every 8 years;

for pipelines with temperatures above 200°C - once every 4 years.

9.3.47. The test pressure and test procedure must comply with the requirements of Section 8 of these Rules.

9.3.48. Periodic testing of pipelines is carried out under the guidance of a person responsible for safe operation, and is documented in an act (Appendix 8).

9.3.49. Persons responsible for the safe operation of pipelines, on the basis of the act, make an appropriate entry in the passport and indicate the date of the next test, and for pipelines for which the passport is not drawn up, an entry is made in the operating log.

Rejection rates

9.3.50. Pipes, pipeline parts, fittings, including cast ones (valve bodies, valves, valves, etc.), are subject to rejection:

if, as a result of the audit, it turns out that due to the influence of the environment, the wall thickness has become lower than the design one and has reached the value determined by the strength calculation without taking into account the allowance for corrosion (rejection size);

if the calculated wall thickness (without allowance for corrosion) turned out to be less than the value indicated below, then the following values are taken as the rejection size:

for pipes, pipeline parts:

outer diameter, mm

(114)

for valve bodies, valves, valves and pipeline castings:

conditional pass, mm

smallest allowable wall thickness, mm

Note. As an exception, deviation from the established norms is allowed in some cases in agreement with the Gosgortekhnadzor of Russia if there is a positive conclusion from a design or specialized organization licensed by the Gosgortekhnadzor of Russia.

The rejection wall thickness of the pipeline elements must be indicated in the design documentation. Pipes and pipeline parts are rejected if:

during the revision, cracks, delaminations, deformations (corrugations, dents, swellings, etc.) were found on the surface;

as a result of the impact of the environment during operation until the next revision, the wall thickness will go beyond the rejection dimensions determined by the strength calculation;

the mechanical properties of the metal have changed and their rejection is required in accordance with the current regulatory and technical documents and these Rules;

when the welds were translucent, defects were found that could not be corrected;

the dimensions of the threaded connections are out of tolerance or there are thread breaks, cracks, corrosive wear on the thread;

the pipeline did not pass the hydraulic or pneumatic test;

the sealing elements of the fittings have worn out so much that they do not ensure the conduct of the technological process, and it is impossible to repair or replace them.

9.3.51. Flanges are rejected when:

unsatisfactory condition of mating surfaces;

the presence of cracks, shells and other defects;

flange deformations;

reducing the wall thickness of the flange collar to the rejection dimensions of the pipe;

thread breakage, crushing and wear in high-pressure threaded flanges, as well as in the presence of a backlash in the thread that exceeds the allowable according to the current NTD. Lenses and gaskets of oval section are rejected in the presence of cracks, nicks, chips, dents of sealing surfaces, deformation.

9.3.52. Fasteners are rejected:

when cracks, breakage or corrosive wear of the thread appear;

in cases of bending bolts and studs;

with residual deformation leading to a change in the thread profile;

in case of wear of the side faces of the heads of bolts and nuts;

in the event of a decrease in the mechanical properties of the metal below an acceptable level.

9.3.53. Bellows and lens expansion joints are rejected in the following cases:

the wall thickness of the bellows or lens has reached the calculated value specified in the compensator passport;

the wall thickness of the bellows has reached 0.5 mm in cases where the design thickness of the bellows is lower;

when operating time by compensators of type KO-2 and KS-2 is 500 cycles and by other types - 1000 cycles, if they are operated in fire-explosive and toxic environments, and the permissible number of cycles for these compensators, determined according to the method of OST 26-02-2079-83, exceeds specified in this paragraph;

when the compensators have worked out the allowable number of cycles, determined by the method set forth in OST 26-02-2079-83.

9.3.54. Rejection rates should be indicated in the repair documentation for a specific object.

9.4. Technical documentation

9.4.1. The following technical documentation is maintained for technological pipelines (appendices 3 - 10 to these Rules):

1. List of technological pipelines (Appendix 7).

2. Passport of the pipeline (Appendix 3). Attached are:

a pipeline diagram indicating the nominal bore, initial and rejection thickness of the pipeline elements, installation locations for fittings, flanges, plugs and other parts, places for drain, purge and drainage devices, welded joints, control drillings (if any) and their numbering;

acts of revision and rejection of pipeline elements (Appendix 5);

certificate of quality of pipeline repairs (Appendix 4). Primary documents, including a welding log for pipeline repair (Appendix 4a), confirming the quality of the materials used in the repair and the quality of welded joints, are stored in the organization that performed the work and presented for verification at the request of the technical supervision service;

documentation for the control of metal of pipelines operating in hydrogen-containing media, in accordance with the NTD.

3. The act of periodic external inspection of the pipeline.

4. The act of testing the pipeline for strength and density (Appendix 8).

5. Acts for the revision, repair and testing of fittings (appendices 6, 6a).

6. Operating log of pipelines (maintained for pipelines for which passports are not drawn up).

7. Journal of installation and removal of plugs (Appendix 9).

8. Journal of heat treatment of welded joints of pipelines (Appendix 10).

9. Conclusion on the quality of welded joints.

9.4.2. The specified technical documentation, together with the passport, is kept by the person responsible for the safe operation of the pipeline.

9.4.3. Forms of technical documentation are recommended. Depending on the structure and composition of the enterprise, it is allowed to make changes, provided that the main content is preserved.

A significant amount of construction of the main facilities in the oil refining, metallurgical, food industries is given to the arrangement of technological pipelines. They play a crucial role in the functioning of strategically important systems. Also, technological pipelines are used in agro-industrial complexes, heat supply systems and in many other industries.

Basic concepts

A pipeline is a device designed to transport a variety of substances. It consists of pipe sections, connecting and shut-off valves, automation and fasteners.

What is the meaning of the term "technological pipelines?" The definition designates them as supply systems for industrial enterprises, through which semi-finished and finished products are transported, as well as substances that ensure the conduct of the entire process.

Location of pipelines

During the laying process, the following recommendations must be followed:

technological pipelines should have a minimum length;
sagging and stagnation are unacceptable in the system;
providing free access for technological control;
the possibility of locating the necessary lifting and transport vehicles;
providing insulation to prevent moisture penetration and retain heat;
protection of pipelines from possible damage;
unhindered movement of fire extinguishing equipment and lifting mechanisms.

Draft angles

The operation of technological pipelines provides for forced shutdowns. To do this, slopes are laid in the project, which will ensure arbitrary emptying of pipes. The device of technological pipelines provides the following slope angle depending on the medium being transported (values are given in degrees):

gaseous medium: in the direction of movement - 0.002, against it - 0.003;
liquid highly mobile substances - 0.002;
acidic and alkaline environment - 0.005;
substances of high viscosity or quick-setting - up to 0.02.

The design may not provide for a slope, then special measures must be taken to empty the pipelines.

Preparatory work

Installation of technological pipelines must be accompanied by the following steps:

Route marking

This operation consists in transferring the axes of fastening of fittings and compensators directly to the place where technological pipelines will be laid. Determination of the markup location can be performed by the following tools:

roulettes;
plumb lines;
level;
hydraulic level;
templates;
squares.

If a large number of technological pipelines are laid for a building, the time allotted for marking is significantly reduced due to the use of special layouts. They give a visual representation of the location of the pipeline lines in relation to the building structure. After marking, all applied elements are compared with the project, after which they begin to fix the supporting structures.

Installation of supports and fasteners

During the arrangement of the foundation of the building, holes must be provided in it for laying bolts, fastening supports. They can be made by mechanized equipment. During the installation of supports, the following recommendations should be taken into account:

Technological pipelines, which have fixed supports, described above, require the installation of fasteners in close proximity to the apparatus and fittings. on such supports should be tightly fixed, not allowing shifts. The same requirements apply to clamps.
Movable supports are mounted with the possibility of unimpeded movement of the pipeline in order to easily extend it if necessary. Also, provision must be made for the safety of thermal insulation during potential movement from expansion.
All installation supports must be checked by the installer of process pipelines for compliance with the horizontal and vertical. Possible deviations are foreseen, which cannot exceed the following limits:

intrashop pipelines - ± 5 mm;
external systems - ±10 mm;
slopes - 0.001 mm.

Insertion into existing systems

Special permits are required for this, and a process piping installer who maintains these lines must be present at the work site. Insertion is carried out when a new mounted component is connected to an existing system. Usually, for such cases, the installation of shut-off equipment is provided, but if there is none in the existing system, then they resort to a tie-in. There are several features here:

The existing pipeline must be disconnected and emptied.
Pipes through which a flammable and explosive medium was transported must be neutralized and washed.
The fitting to be welded must pass preliminary tests. The steel grade is also established according to the documentation.
Welding work must be carried out by a highly qualified specialist who has a special permit for critical structures.
Before installation of process pipelines begins, the connecting assembly must pass all tests.

Purging and flushing

The assembled pipeline is subjected to cleaning, the method of which depends on the size of the pipe:

diameter up to 150 mm - washed with water;
over 150 mm - purged with air;

The area to be cleaned must be isolated from other pipelines with plugs. Flushing with water is carried out until water begins to flow from the pipe without contamination. Purge is carried out for 10 minutes. These methods are used if the technology does not provide for other cleaning standards. After the work done, you can proceed to the tests, which are performed in two ways: hydraulic and pneumatic.

Hydraulic tests

Before checking, technological pipelines are divided into separate conditional sections and the following activities are carried out:

control by external inspection;
verification of technological documentation;
installation of air valves, temporary plugs (the use of permanent equipment is prohibited);
shutdown of the test segment;
connecting the test section to a hydraulic pump.

Thus, the strength and density of the pipeline are checked simultaneously. To establish the degree of strength, the special value of the test pressure is taken into account:

Steel pipelines operated at operating pressures up to 5 kgf/m². The value of the test parameter is 1.5 of the working pressure, but not less than 2 kgf / m².
Steel pipes operating at pressures exceeding 5 kgf/m². The value of the test parameter will be 1.25 working pressure;
Cast iron, polyethylene and glass - 2 kgf / m².
Non-ferrous metal pipelines - 1 kgf / m².
For pipes made of other materials - 1.25 working pressure.

The holding time under the set pressure value will be 5 minutes, only for glass pipelines it is quadrupled.

Pneumatic tests

For testing, either an inert gas is used, which is taken from factory networks or from portable compressors. This option is preferred in cases where hydraulic tests are not possible for a number of reasons: lack of water, very low air temperature, and also when dangerous stresses can arise from the weight of water in the pipeline structure. The value of the ultimate test pressure depends on the size of the pipeline:

with a pipe diameter of up to 200 mm - 20 kgf / m²;
200-500 mm - 12 kgf / m²;
over 500 mm - 6 kgf / m².

If the pressure limit is different, special test instructions should be developed for such conditions.

Pneumatic test requirements

Pneumatic testing is prohibited for ground cast iron and glass structures. For all other materials from which process pipelines can be made, there are special requirements for testing:

the pressure in the pipeline increases gradually;
inspection can be carried out when the pressure reaches 0.6 of the working value (it is unacceptable to increase it during work);
Leak testing is carried out by coating with soapy water; tapping with a hammer is prohibited.

The results of hydraulic and pneumatic tests are considered satisfactory if during their implementation there was no pressure drop on the pressure gauge.

Transfer of pipelines to operation

At all stages of installation, relevant documents are drawn up, fixing the types of work, tolerances, tests, etc. They are transferred at the stage of delivery of pipelines as accompanying documentation, they include:

acts of delivery of supporting structures;
certificates for welding consumables;
protocol for internal cleaning of the pipeline;
certificates of quality control of welded joints;
conclusion on the testing of valves;
acts and density;
a list of welders who performed the connections, and documents confirming their qualifications;
schemes of pipeline lines.

Technological pipelines are put into operation along with industrial installations, buildings and structures. Separately, only intershop systems can be rented out.

Periodic control should include the following operations:

Checking the technical condition during external inspection and non-destructive methods.
Checking areas subject to vibration with special devices that determine its frequency and amplitude.
Troubleshoot issues that have been identified during previous checks.

Equally important is the safe operation of process pipelines, which is ensured by compliance with all established rules.

Monthly system health checks should cover the following:

flange connections;
welds;
insulation and coating;
drainage systems,
support fasteners.

If leaks are detected, for safety reasons, the operating pressure must be reduced to atmospheric pressure, and the temperature of the heating lines must be lowered to 60 ° C to carry out the necessary troubleshooting measures. The results of the check should be recorded in special journals.

revision

This is used to determine the condition and operational capabilities of pipelines. It is advisable to conduct an audit in areas where the operation of technological pipelines is carried out in particularly difficult conditions. The latter include vibration, increased corrosion.

The audit of pipelines includes the following operations:

Checking the thickness of the structure by non-destructive methods.
Measurement of areas subject to creep.
Inspection of welded joints that are in doubt.
Examination
The condition of the anchorages.

The first audit control should be carried out after a quarter of the period specified in the regulatory documents, but no later than 5 years after the launch of the facility. As a result of the timely conduct of all checks, the safe operation of process pipelines will be ensured.

Pipelines are designed to transport compressed air, water, steam, various gases and liquids. In order to quickly determine the content of pipelines, and therefore comply with the relevant safety requirements by workers when approaching them, ten groups of substances have been established and the corresponding distinctive color of the pipelines with which they are transported: the first is water (green), the second is steam (red), the third is air (blue), fourth and fifth - flammable and non-flammable gases, including liquefied gases (yellow), sixth - acids (orange), seventh - alkalis (purple), eighth and ninth - flammable and non-flammable liquids (brown), zero - other substances ( grey). Distinctive coloring of pipelines is carried out along their entire length or in separate sections, depending on location, illumination, size, etc. In order to highlight the type of danger, signal color rings are applied to pipelines: red - for flammable, explosive - and flammable substances; yellow - for harmful and hazardous substances (poisonous, toxic, radioactive) green - for safe and neutral substances. Sometimes, to specify the type of hazard, in addition to the signal color rings, warning signs, marking plates and inscriptions on pipelines in the most dangerous places of communications are used. flyovers, columns, walls of buildings, etc.). If possible, it is advisable to carry out ground and above-ground laying of pipelines, since then it is easy to inspect and check their condition. In addition, the service life of such pipelines is two to three times longer than that of underground pipelines. Pipelines are made from seamless pipes with welded joints. To facilitate installation and repair on the pipeline, flange connections are installed in convenient and accessible places. Pipelines are laid with a certain slope (1:500) in the direction of gas flow, and separators with drain valves are installed in low places to extract condensate and water. pipelines, compensatory elements are provided: expansion loops, lyre-shaped pipes, stuffing box compensators, etc. The most common are U-shaped compensation loops, which allow you to evenly distribute thermal deformations along the pipeline. To ensure safety on the pipeline, serviceable and properly adjusted pressure reducing, check, shut-off and safety valves must be installed. Pressure reducing valves (pressure regulators) maintain the set pressure values in the system, regardless of changes in gas or liquid consumption by consumers. Check valves allow gas or liquid to pass through the pipeline in only one direction, therefore, they prevent their reverse movement in case of emergencies (for example, a fire in a combustible gas pipeline). Check valves automatically open when the permissible pressure is exceeded, and part of the gas or liquid is released into the atmosphere or the disposal channel. If poisonous, toxic, explosive or flammable gases or liquids are transported through the pipeline, then safety valves must be of a closed type (when opening, gas or liquid is released into a closed system). Pipelines are periodically subject to external inspections and hydraulic tests. During external inspections, the condition of welded and flanged joints, glands is determined, slopes, deflections, strength of bearing supports and structures are checked. During hydraulic tests, the tightness and strength of the pipeline are checked. If during the hydraulic test the pressure in the pipeline did not drop, and no cracks, ruptures, leaks were found on the welds, flange joints, housings of safety devices, then the test result is considered satisfactory. Thus, the safety of pipeline operation is ensured by their correct laying, high-quality installation, installation of compensation elements, necessary safety devices and fittings, control of their technical condition and timely repair. Natural gas is widely used in many enterprises and households, most often as a fuel. Given that natural gas is an explosive substance, the gas pipeline, together with installations that regulate the supply of gas and work on it, is an object of increased danger, therefore, it requires special care during operation. As a rule, the cause of accidents, explosions, fires during the operation of gas facilities and gas pipelines is a gas leak. Since natural gas is odorless, an odorant, a substance with a strong odor (for example, ethyl mercaptan), is added to it to quickly detect its leakage. To prevent the occurrence of dangerous induced currents that can cause explosions and fires, gas pipelines must be grounded and conductive jumpers installed on all flange connections.