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Pipeline construction procedures


Pipeline construction procedures

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  • Time of issue:2011-04-29 02:37
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(Summary description)I. Scope: This procedure is applicable to the construction of excavation, backfilling of pipelines in station yards, pipe loading and unloading, reverse transportation, prefabrication, installation, inspection, pressure test, cleaning, anticorrosion and insulation. Ii. Reference Documents Tender Documents of the Owner

Pipeline construction procedures

(Summary description)I. Scope: This procedure is applicable to the construction of excavation, backfilling of pipelines in station yards, pipe loading and unloading, reverse transportation, prefabrication, installation, inspection, pressure test, cleaning, anticorrosion and insulation. Ii. Reference Documents Tender Documents of the Owner


  I. Scope

  This procedure is applicable to the construction of excavation, backfilling of pipelines in station yards, pipe loading and unloading, reverse transportation, prefabrication, installation, inspection, pressure test, cleaning, anticorrosion and insulation.

  Reference documents

  Owner's tender documents

  The owner's general technical requirements are 5010-A, 5020-A, 5030-A, 5141-A, 5200-A, 5900-A, 8100-A, 8400-A and their specifications and standards.

  CPECC (China Petroleum Construction Engineering Corporation) Specifications

  On-site material loading, unloading, storage and distribution control procedures—MBOD / EPC Ⅰ—MU—QC Ⅲ.8

  When there are several specifications for a project, the strictest one will be observed during construction. If there is a conflict between the specifications, before the start of any work, the owner will be consulted and a written ruling will be obtained from the owner.

  Third, the main construction process of station pipeline installation (omitted)

  Fourth, the pipe anticorrosion and painting

  1. Before sandblasting and rust removal, check whether the ovality, wall thickness and material of all pipes meet the material specifications, otherwise they must not be used.

  2. Sand blasting and rust removal shall remove paint, grease, oxides, etc. on the surface of the pipeline, and shall be approved and recorded by the QC department and the owner before corrosion and painting.

  3. Pipe anticorrosion shall be carried out according to drawings and specifications.

  4. Before painting, the primer should be fully stirred and mixed, and the dust and moisture on the surface of the pipe should be removed with cotton yarn head or compressed air. The rust-removing pipe on the day must be brushed with the first primer on the day. Brush the second primer, the primer on the surface of the pipeline should be uniform, no leaks.

  5.Leave more than 50mm at both ends of the pipe without painting. Try to put together the pipes of the same specifications, wall thickness and material to remove the rust. After the rust is removed, it should be marked and transplanted. After the primer is painted, each pipe must be marked. transplant.

  6. After the pipe is derusted and painted, the two ends of the pipe should be closed. To prevent the pipeline coating from being damaged during transportation and lifting, protective measures should be taken.

  V. Pipe Prefabrication and Installation


  (1) The general technical requirements and CPECC specifications provided by the owner of the pipeline construction shall be implemented. If there is a conflict between the two, the specifications required by the owner shall be the main.

  (2) Welders for pipeline prefabrication and installation must pass the assessment and obtain corresponding certificates in accordance with approved procedures before they can take up their posts.

  (3) All pipes, pipe fittings, loading, unloading, storage and collection shall follow the material loading, unloading, storage and distribution procedures—MBOD / EPC Ⅰ—MU—QC Ⅲ.8.

  (4) Prefabrication Prefabrication shall be performed according to the approved one-line diagram, and the technician shall mark the prefabrication scope on the one-line diagram.

  (5) Pipe welding should follow the process pipe welding procedure-MBOD / EPC1-RP-WLD-06.

  2. Pipe prefabrication

  (1) The prefabrication of pipes is limited to pipes above 2 ″. Except for the prefabrication of skid-mounted equipment pipes in the workshop, the others are prefabricated on site.

  (2) Pipes and fittings shall be collected by the construction team three days in advance, and the technical staff shall verify them. The team shall send a special person to collect them. The picking list shall be kept and the materials shall be sorted and put away. Before cutting and matching, carefully check the pipes and fittings, confirm the material, wall thickness and specifications, and replace the non-standard materials such as pipe deformation, severe scratches, damage to flanges and valve sealing surfaces, and cracks in pipes. Records should be made and non-conforming materials should be marked clearly to prevent misuse next time.

  3. Pipe cutting

  (1) Mechanical and fire welding can be used for pipe cutting. Carbon steel pipes under 2 ″ can be cut with a cutting machine. Stainless steel pipes cannot be cut with fire welding. Stainless steel pipes under 2 ″ can be cut with a cutting machine. Stainless steel above 2 ″ Pipes are cut with a plasma cutter or mechanical method. After cutting, the surface oxide and metal slag should be removed. Galvanized pipes should be cut with a cutter.

  (2) When cutting the pipe, in consideration of cutting and grinding and welding shrinkage, allow 1-2mm allowance when the pipe is unloaded, and allow more than 100mm allowance at the installation and fixing mouth.

  (3) After cutting, each section of cutting material should be marked with transplantation, indicating the material, wall thickness and specifications. After cutting, the unmarked pipes cannot be used for the time being without identification.

  4. Bevel processing

  (1) The groove is machined by mechanical methods or by fire welding, but it must be smoothed by an angle grinder to remove oxide slag. The groove angle meets the welding requirements. The inner and outer surfaces of the groove should be welded before welding. Each 25mm should be cleaned. The cotton yarn head and wire brush should be used to remove water, oil stains, splashes and paint. Stainless steel must be cleaned with a stainless steel brush.

  (2) After the bevel is processed, the appearance inspection shall be performed. No defects such as cracks and slag inclusions shall be found. The bevels that have been cleaned and inspected shall be completed in a timely manner and records shall be made.

  5. Welding pair

  (1) Pairs of pipelines, bevel clearances and angles meet the requirements of the code. When pipes and fittings with the same wall thickness are aligned, the inner wall should be flush. For different pairs of pipe and pipe fittings with different wall thicknesses, when the difference between the two wall thicknesses is greater than 1.5mm, they should be processed as required. Pipe assembly and debris should be cleaned during assembly. For small pipes, compressed air is used for cleaning. For large pipes, cotton yarn heads or pigs can be used for cleaning. After cleaning and cutting, the two ends of the pipes should be closed.

  (2) Spot welding and welding shall be carried out in accordance with the pipeline welding procedure—MBOD / EPC Ⅰ—RP—WLD—06.

  (3) The collection and storage of welding materials shall be carried out in accordance with the welding material control program—MBOD / EPC Ⅰ—RP—WLD—01.

  (4) After each weld is finished, grind each joint on the surface of the weld. The welder should put his own steel quotation marks at a distance of 50mm from the weld. Mark stainless steel pipes with paint or marker and mark them on a single line. Mark the welder number at the corresponding position on the drawing, and fill in the group butt welding record.

  (5) Welding shape and geometry meet ASME B31.3 requirements.

  6. Pipe openings can be opened by fire welding, but must be cleaned with a polisher and wire brush.

  7, non-destructive testing requirements in accordance with the welding inspection procedures-MBOD / EPC Ⅰ-RP-WLD-04 requirements.

  8. The dimensional deviation of the prefabricated parts shall meet the requirements of the specification.

  9. For prefabricated short pipes, use metal plates to tie the short pipes with iron wires or use paint as marks. Both ends of the prefabricated short pipes are protected by the following measures:

  (1) For all short pipes with flanges, wooden protection plates shall be bolted to the flange holes with metal wires at the flange ends.

  (2) The ends of all non-flange short pipes are fitted with plastic caps.

  10. Make a record of the prefabricated short tube. Temporary support is required when the prefabricated part is loaded and unloaded to prevent paint damage and short tube deformation. The short pipes transported out of the prefabrication yard shall be handed over and registered. A single-line diagram and various construction records shall be provided during the transfer. The prefabrication status and welder number shall be marked on the single-line diagram.

  11.Bending and forming

  The bending of the pipe uses two methods: cold bending and hot bending. Cold bending uses sand filling method. Hot bending uses fire welding heating method. On a fixed tire, the pipe surface is uniform after molding to avoid cracks and no deformation.

  12.Prefabrication of pipe support

  (1) The material used for the pipe support meets the requirements of the specification, and the material model, specifications, processing dimensions and welding meet the requirements of the drawings.

  (2) All holes of the pipe bracket cannot be opened by flame welding. The weld of the pipe bracket should be visually inspected, and there must be no defects such as missing welding, under-welding, and cracks.

  (3) The produced brackets should be derusted, painted, and marked with material, model, and classified for storage.

  13.Thread processing

  All pipe threads are processed in the prefabricated field. The pipes used for processing the threads meet the requirements of the drawings. Protective measures should be taken for the threads and sealing surfaces.

  Six, pipeline installation

  1. Valve inspection

  (1) The valve should be taken from each batch (same manufacturer, same specification, same model, and arrived at the same time) for strength and tightness test. If it fails, increase the proportion of random inspection. If there is still a failure, then Need to check one by one.

  (2) Valves installed in key parts shall be tested by pressure test.

  (3) Valves that pass the pressure test shall be drained of the internal water collection in a timely manner, and the sealing surface shall be coated with rust preventive oil. Repair the unqualified valve and test again.

  2.Safety valve constant pressure

  (1) The safety valve should be commissioned according to design requirements before installation (before commissioning). When there is no design requirement, the opening pressure is 1.05-1.15 times the working pressure, and the seat pressure should be greater than 0.9 times the working pressure. The pressure is stable, and the opening and closing test of each safety valve should not be less than three times. During the commissioning, the relevant personnel of the owner are on site, after the commissioning, fill in the records and seal them.

  (2) Debugging medium:

  A. The working medium is adjusted by air or inert gas.

  B. When the working medium is liquid, debug with water.

  3. Conditions for pipeline installation:

  (1) The civil engineering related to the pipeline is qualified and meets the installation requirements.

  (2) The equipment connected to the pipeline is qualified and fixed.

  (3) The pipeline prefabrication has been handed over, the valves and fittings have passed the inspection, and various accessories are complete.

  4, ground pipe installation

  (1) Considering the station site, the ground pipe and pipe trench are excavated manually. Before excavation, the line should be laid according to the drawing. The excavated earthwork should be stacked as far as possible. After the trench is excavated, the pipe bottom elevation and coordinates should be checked The bottom should be tamped.

  (2) Be careful not to damage the anti-corrosion layer when the trench is under the ground pipe. The two ends of the pipe should be closed to prevent debris from entering the pipe.

  5. Before installing the pipeline, clean the pipeline and fittings with compressed air and make a record.

  6. Check the straightness of the pipe when it is mated. The pipe connection must not use strong mating or heating the pipe to eliminate defects such as gaps, deviations and misalignments on the end face of the interface.

  7. The opening and welding of instrument contacts on the pipeline should be completed before the pipeline installation.

  8. When installing stainless steel pipes, do not strike with iron tools. 9. For flanges connected to containers, equipment and pumps, temporary asbestos blind plates are used for installation. The fixed welds of pipes connected to moving equipment are far away from the equipment. After the pipeline installation is qualified, the moving equipment must not bear additional loads outside the design.

  10.Valve installation

  (1) Before the valve is installed, check the model according to the drawing, determine the installation direction according to the flow direction of the medium, check whether the flange sealing surface is damaged, the operating mechanism and the transmission device should be adjusted as necessary, and the butt welding valve should not be closed during welding.

  (2) Protective measures should be taken to prevent damage to the instrument when installing the regulating valve.

  11, support, hanger installation

  (1) The support and hanger should be fixed and adjusted in time, the guide bracket should be installed flat and firm, and the sliding surface of the sliding bracket should be flat.

  (2) The spring installation height of the spring support and hanger should be adjusted according to the design requirements and recorded.

  (3) When welding the supports, hangers and pipes, the welds should be carefully checked.

  (4) After the installation of the pipeline is completed, the form and position of the support and hanger should be checked one by one according to the requirements of the drawings.

  12. Temporary gaskets should be used for pipe parts and equipment and pump inlet and outlet positions that need to be removed during pressure test and purge. Other parts can be fitted with formal gaskets.

  13. Ground pipe backfill

  The ground pipe can be backfilled only after the pressure test, anticorrosion and fill inspection are qualified, and the backfilling method is manual layered backfilling.

  Seven, pressure test

  The following conditions should be met before the piping system test:

  1. The pipeline system is completed according to the drawings, and the supports and hangers are installed, and checked according to the drawings

  (1) Finished.

  (2) After the non-destructive testing is completed, the weld and other parts to be inspected shall not be painted.

  (3) Coordinates, elevations, slopes, bases, and cushions of buried pipelines are qualified after re-examination. The temporary reinforcement measures used in the test were verified to be safe and reliable.

  (4) The various QC forms to be filled in accordance with the quality plan and procedures are complete and approved by the QC Department and relevant departments.

  (5) The pressure gauge used in the test has been verified, the accuracy is not less than 1.5, the full scale value of the meter is 1.5-2 times the maximum pressure, and the pressure gauge is not less than two.

  (6) Develop a flow chart of the pressure test system. In the figure, the position of the pressure gauge is required, and the place where the blind plate needs to be added.

  (7) The pressure test application form has been reviewed and approved by the relevant departments. 2. The systems, equipment, instruments and pipeline accessories that are not involved in the pressure test shall be isolated before the pressure test. The positions of the blind plates shall be marked and recorded.

  3. Check the process before pressure test, open the relevant valve, if the flow direction of the pressure test medium is opposite to the flow direction of the check valve, remove the valve core. The removed valve core should be marked and recorded, and then tested and flushed. installation.

  4.Pressure test medium

  (1) Considering the problem of water source, it is recommended that the pressure test of low-pressure pipelines is based on air pressure test, supplemented by water pressure test.

  (2) If the pressure test medium of austenitic stainless steel pipe is water, only water with a chloride ion content of less than 50 ppm can be used.

  5.Test pressure

  (1) The hydrostatic test pressure shall not be less than 1.5 times the design pressure.

  (2) The air pressure test pressure is 1.1 times the design pressure.

  (3) For pipelines with a design temperature higher than the test temperature, the minimum test pressure shall be in accordance with the requirements of ASME.B31.3.

  6.Pressure test steps

  (1) When the water pressure test system is filled with water, try to fill it from the bottom of the pipeline, and exhaust the air inside the system at the highest point of the pipeline system. A pressure gauge must be installed at the highest point.

  (2) Slowly increase the pressure. After reaching the test pressure, stop the pressure for 10 minutes. If there is no pressure drop, visual inspection of the pipeline is not deformed, and then the pressure drops to the design pressure, a comprehensive inspection of the pipeline system including but not limited to welds, valves, Lankou passed the comprehensive inspection of the pipeline system for leakage and pressure drop. If a leak is found, it should be depressurized and must not be operated under pressure.

  (3) Air pressure test, the pressure should be gradually increased, first to 50% of the test pressure, check all welds, valves, flanges, no leakage and no abnormalities, continue to gradually increase the pressure of 10% of the test pressure until The test pressure is stabilized for 3 minutes for each stage, and 5 minutes after the test pressure is reached. If there is no pressure drop, no visual deformation, and then the pressure drops to the design pressure, check the welds, valves and flanges with soapy water If there is no leakage, the pressure is not reduced to qualified for 30 minutes. If a leak is found, it should be depressurized and not under pressure.

  (4) The safety requirements for pressure tests shall be as specified in the safety procedures.

  (5) The pressure test is approved by the relevant personnel of the owner. After the test, the pressure test record should be filled in time. The record form is shown in the form in the QC quality plan.

  Eight, system cleaning and purge

  1. The following conditions should be met before system cleaning and purging:

  (1) Prepare the system cleaning and purge flow chart. The direction and sequence of cleaning and purge need to be marked in the figure.

  (2) The system pipeline pressure test is approved.

  (3) The orifice plate, venturi tube, nozzle, filter screen, regulating valve and flow meter on the piping system shall be removed and replaced with short pipes.

  (4) The pipes and equipment not involved in cleaning and purging have been isolated from the system.

  (5) The system has been temporarily strengthened.

  2. Water flushing should be carried out continuously, the flow velocity of the water should not be less than 1.5 m / s, and the flushing discharge port should be as close to the drainage well or ditch as possible. When there is no design requirement, the flushing is qualified by the color and transparency of the outlet and the visual inspection of the inlet.

  3. The air purge uses industrial wind or instrument air. Considering the wind pressure and flow, the purge cannot be carried out continuously. Use a white cloth or a white painted wooden board at the exhaust port to check that the board is free of rust, dust and other dirt Things are qualified.

  4. When the pipeline is cleaned and purged, relevant personnel of the owner shall participate, and fill in the pipeline system cleaning and purging records after passing.

  Nine, pipeline system reset

  1. After the pressure test of the pipeline system is qualified, the pipeline should be reset immediately. It is required to press the pressure test and purge the orifice plate, venturi tube, nozzle, filter screen, regulating valve and flow meter, check valve core, etc. The blueprints are required to be installed. The blind plates added during the test pressure purge should be removed, and all temporary gaskets should be replaced with formal gaskets.

  2. For pipelines connected to moving equipment, the flange parallelism should be readjusted before resetting. The pipeline and equipment are finally closed and connected. Recheck that the radial displacement of the equipment's coupling shaft cannot exceed the manufacturer's requirements, otherwise readjust the pipeline until it is qualified.

  3. Remove all temporary supports added during pressure test and purge, and recheck and adjust all supports, hangers and spring-supported hangers to meet the drawing requirements.

  4. The closed system of the pipeline system should be filled in for resetting the pipeline system.

  Ten, pipeline corrosion and insulation

  1. Ground pipe anticorrosion

  (1) After passing the pressure test, anti-corrosion is performed on all welds. First, use a grinder to remove rust and weld grate from the weld.

  (2) Before the ground pipe is backfilled, use an EDM leak detector to detect leaks, repair the damaged parts, and then use the EDM leak detector to check again until it is qualified. After being approved by the owner, fill in the EDM leak detector in time. Inspection records.

  2.Pipe painting

  (1) After the pipeline pressure test is qualified, the welds and fittings shall be derusted with a polisher. The primer may be applied only after approval by the relevant authorities. The on-site painting shall generally be naturally dry, and the interval before and after multi-layer painting shall ensure The paint is dry, and the coating is not allowed to proceed to the next step without being fully dried.

  (2) Welding seams, pipe primers and pipe primers have been repaired. Fill in the records in a timely manner, and the topcoat can only be applied after approval by the relevant authorities.

  3. The coating quality meets the following requirements:

  (1) The coating is uniform and the color is consistent.

  (2) The coating is complete, no damage and no missing coating.

  (3) The coating adheres firmly without wrinkles, bubbles, pinholes, etc.

  Eleven, pipe insulation

  1. The piping system can be kept warm only after passing pressure test and painting.

  2. Pipeline insulation materials can only be used after passing the inspection. The insulation of valves and flanges should be easy to disassemble and install, and the insulation layer should not prevent the replacement of fillers.

  3. The insulation construction of non-horizontal pipelines should be from bottom to top. When the moisture-proof layer and protective layer are overlapped, the width should be 3050mm. The moisture-proof layer should be complete and tight, uniform in thickness, without pores, cracks, etc. After the insulation layer has passed the inspection, the metal protective layer can be applied.

  4. The metal protective layer should be blanked, fastened, and should not have shelling or unevenness. The rings and longitudinal seams should overlap or bite, the seam should face down, and the self-tapping screws should not be fastened to penetrate the moisture-proof layer.

  Twelve, construction quality records and inspection reports

  1. The construction quality records should be synchronized with the construction and accurately and truly reflect the construction situation. QC engineers and technicians should always check various records, and the construction team should have a special person responsible for recording.

  2. The inspection report is completed by a QC engineer, which truly reflects the inspection content and quality, and is approved by the owner's relevant personnel.

  3. For construction quality records and inspection forms, see the pipeline system section in the quality plan.

  Thirteen, modify the note

  If it is found that this procedure does not fully guarantee the completion of the project / encounters new construction conditions / new site conditions or upon the request of the owner, the procedure will be modified.

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