I. Scope

　　This procedure applies to the excavation and backfilling of pipelines and trenches at the station site, as well as the on-site loading, unloading, transportation, prefabrication, installation, inspection, pressure testing, cleaning, corrosion prevention, and insulation of pipe materials.

　　II. Reference Documents

　　Owner's bidding documents

　　Sections 5010-A, 5020-A, 5030-A, 5141-A, 5200-A, 5900-A, 8100-A, and 8400-A of the owner's general technical requirements, including the specifications and standards therein.

　　CPECC (China Petroleum Construction Corporation) Standards

　　On-site Material Loading, Storage, and Issuance Control Procedure—MBOD/EPC Ⅰ—MU—QC Ⅲ.8

　　If an engineering project has several specifications and standards, the strictest one will be followed during construction. If conflicts arise between specifications, the owner will be consulted and a written decision obtained before any work commences.

　　III. Main Construction Procedures for Station Pipeline Installation (omitted)

　　IV. Pipe Corrosion Prevention 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 shall not be used.

　　2. Sandblasting and rust removal should remove paint, grease, oxides, etc., from the pipe surface. This must be approved by the QC department and the owner, and a record must be kept before corrosion prevention and painting can proceed.

　　3. Pipe corrosion prevention shall be carried out according to the drawings and specifications.

　　4. Before painting, the primer should be thoroughly stirred and mixed. Use cotton swabs or compressed air to remove dust and moisture from the pipe surface. Pipes that have been derusted on the same day must be primed with the first coat on the same day. The second coat of primer should not be applied before the first coat is dry. The primer on the pipe surface should be uniform and without any pinholes.

　　5. Leave more than 50mm unpainted at both ends of the pipe. Pipes of the same specification, wall thickness, and material should be derusted together as much as possible. After derusting, they should be marked and transplanted. After priming, each pipe must be marked and transplanted.

　　6. After derusting and painting, both ends of the pipe should be sealed. Protective measures should be taken during transportation and hoisting to prevent damage to the pipe coating.

　　V. Pipe Prefabrication and Installation

　　1. General Principles

　　(1) Pipeline construction shall follow the owner's provided general technical requirements and CPECC specifications. In case of conflict, the owner's requirements shall prevail.

　　(2) Welders for pipe prefabrication and installation must pass the assessment according to the approved procedures and obtain the corresponding certificates before they can take up their posts.

　　(3) All pipe materials and fittings loading, unloading, storage, and receipt shall follow the Material Loading, Storage, and Issuance Procedure—MBOD/EPC Ⅰ—MU—QC Ⅲ.8.

　　(4) Prefabrication shall be carried out according to the approved single-line diagram, and the prefabrication scope shall be marked on the single-line diagram by the technician.

　　(5) Pipe welding shall follow the Process Pipe Welding Procedure—MBOD/EPC1-RP-WLD-06.

　　2. Pipe Prefabrication

　　(1) Pipe prefabrication is limited to pipes of 2 inches and above. Except for the pipes of skid-mounted equipment that are prefabricated in the workshop, the rest are prefabricated on-site.

　　(2) Pipe materials and fittings shall be requested by the construction team three days in advance. The technical personnel shall verify the request, and the team shall assign a dedicated person to collect the materials. The material receipt should be kept, and the materials should be classified and stored properly. Before cutting and assembling, the pipe materials and fittings should be carefully inspected to confirm the material, wall thickness, and specifications. Materials that do not meet the specifications, such as pipe deformation, serious scratches, damage to flange and valve sealing surfaces, cracks in fittings, etc., should be replaced and recorded. Materials that do not meet the specifications should be clearly marked to prevent misuse in the future.

　　3. Pipe Cutting

　　(1) Pipe cutting can be done using mechanical or flame cutting methods. Carbon steel pipes below 2 inches can be cut with a cutting machine. Stainless steel pipes cannot be flame cut. Stainless steel pipes below 2 inches can be cut with a cutting machine, while those above 2 inches should be cut with a plasma cutting machine or mechanical methods. After cutting, the surface oxides and metal slag should be removed. Galvanized pipes should be cut with a cutting machine.

　　(2) When cutting pipe materials, considering the shrinkage caused by cutting, grinding, and welding, a 1-2mm allowance should be left when cutting the pipes. An allowance of more than 100mm should be left at the fixed installation points.

　　(3) After cutting, each piece of cut material should be marked and transplanted, indicating the material, wall thickness, and specifications. Unmarked pipe materials that have not been identified cannot be used temporarily.

　　4. Bevel Processing

　　(1) Bevels can be processed using mechanical methods or flame cutting, but they must be ground smooth with an angle grinder to remove oxide slag. The bevel angle must meet the welding requirements. Before welding, the inner and outer surfaces of the bevel and 25mm on both sides should be cleaned. Cotton swabs and wire brushes should be used to remove water, oil stains, spatter, and paint. Stainless steel must be cleaned with a stainless steel brush.

　　(2) After bevel processing, a visual inspection should be carried out to ensure that there are no cracks, slag inclusions, or other defects. Cleaned and inspected bevels should be welded promptly, and records should be kept.

　　5. Weld Joint Assembly

　　(1) For pipe assembly, the bevel gap and angle must meet the specification requirements. When assembling pipes and fittings with the same wall thickness, the inner walls should be flush. The misalignment should not exceed 10% of the wall thickness and should not be greater than 1mm. For pipes and fittings with different wall thicknesses, if the difference in wall thickness is greater than 1.5mm, processing should be carried out as required. When assembling pipes, debris inside the pipes and fittings should be cleaned. For small pipes, compressed air should be used for cleaning, while for large pipes, cotton swabs or pipe cleaners can be used. After cleaning, cutting, and assembly, both ends of the pipes should be sealed.

　　(2) Spot welding and welding shall be carried out according to the Pipe Welding Procedure—MBOD/EPC Ⅰ—RP—WLD—06.

　　Welding material receipt and storage shall be carried out in accordance with the welding material control procedure—MBOD/EPC Ⅰ—RP—WLD—01.

　　After each weld is completed, the surface of each joint of the weld seam shall be ground. The welder shall mark his own steel quotation mark 50mm away from the weld seam. For stainless steel pipes, use paint or a marker pen to mark, and mark the welder's number at the corresponding position on the single-line diagram, and fill in the assembly welding record at the same time.

　　The welding shape and geometric dimensions meet the requirements of ASME B31.3.

　　6. Pipe openings can be opened by fire welding, but the spatter must be cleaned with a polishing machine and a wire brush.

　　7. Non-destructive testing requirements shall be carried out in accordance with the welding inspection procedure—MBOD/EPC Ⅰ—RP—WLD—04.

　　8. The dimensional deviations of prefabricated components shall meet the requirements of the specifications.

　　9. For prefabricated short pipes, use a metal plate and tie it to the short pipe with iron wire or use paint to mark it. The two ends of the prefabricated short pipe shall be protected by the following measures:

　　(1) For all short pipes with flanges, a wooden protective plate shall be tied to the flange hole with metal wire at the flange end.

　　(2) Install plastic caps at the ends of all non-flanged short pipes.

　　10. Keep a record of the prefabricated short pipes. Temporary supports are required when loading and unloading prefabricated components to prevent paint damage and deformation of short pipes. Short pipes transported out of the prefabrication site shall be transferred and registered. Single-line diagrams and various construction records shall be provided during transfer. The prefabrication situation and welder's number shall be marked on the single-line diagram.

　　11. Bending and forming

　　Pipe bending uses two methods: cold bending and hot bending. Cold bending uses the sand-filling method, and hot bending uses fire welding heating. On a fixed jig, the pipe surface is uniform after forming, avoiding cracks and deformation.

　　12. Pipe support prefabrication

　　(1) The materials used for pipe supports meet the requirements of the specifications. The material model, specifications, processing dimensions, and welding meet the drawing requirements.

　　(2) No holes in pipe supports can be opened by fire welding. The welds of pipe supports shall be visually inspected and shall not have defects such as leakage, under-welding, and cracks.

　　(3) The fabricated supports shall be derusted, painted, and marked with the material and model, and classified and stacked.

　　13. Thread processing

　　All pipe threads are processed in the prefabrication field. The pipe materials used for processing threads meet the drawing requirements, and protective measures shall be taken for the threads and sealing surfaces.

　　VI. Pipeline Installation

　　1. Valve inspection

　　(1) Valves shall be sampled from each batch (same manufacturer, same specification, same model, and same arrival time) for strength and tightness tests. If there are unqualified valves, the sampling ratio shall be increased. If there are still unqualified valves, each valve shall be inspected.

　　(2) Valves installed in key positions shall be pressure tested.

　　(3) For pressure-tested qualified valves, the internal accumulated water shall be drained in time, the sealing surface shall be coated with rust-proof oil, the valve shall be closed, the inlet and outlet shall be sealed, and the marking and record shall be made. Unqualified valves shall be repaired and pressure tested again.

　　2. Safety valve pressure setting

　　(1) Before installation, the safety valve shall be adjusted according to the design regulations (before commissioning). When there is no design regulation, the opening pressure is 1.05-1.15 times the working pressure, and the reseating pressure shall be greater than 0.9 times the working pressure. The pressure shall be stable during adjustment, and each safety valve shall be tested for opening and closing no less than three times. Relevant personnel from the owner shall be present during the adjustment. After the adjustment, a record shall be filled in and sealed with lead.

　　(2) Adjustment medium:

　　A. For gaseous working media, air or inert gas shall be used for adjustment.

　　B. For liquid working media, water shall be used for adjustment.

　　3. Conditions for pipeline installation:

　　(1) The civil engineering works related to the pipeline have been inspected and qualified and meet the installation requirements.

　　(2) The equipment connected to the pipeline has been checked and fixed.

　　(3) The pipeline prefabrication has been handed over, the valves and fittings have been inspected and qualified, and all accessories are complete.

　　4. Underground pipe installation

　　(1) Considering the site conditions, the underground pipe trenches are excavated manually. Before excavation, the lines shall be laid out according to the drawings. The excavated earthwork shall be piled up on one side as much as possible. After the trench is excavated, the bottom elevation and coordinates of the pipe shall be checked, and the pipe bottom shall be compacted.

　　(2) When laying the underground pipe, pay attention not to damage the anti-corrosion layer. Both ends of the pipe shall be sealed to prevent debris from entering the pipe.

　　5. Before pipeline installation, the pipeline and fittings shall be cleaned with compressed air, and a record shall be made.

　　6. When the pipes are connected, check the straightness. The pipeline connection shall not use forceful connection, heating the pipe, etc., to eliminate defects such as gaps, deviations, and misalignment at the interface end face.

　　7. The opening and welding of instrument connection points on the pipeline shall be completed before the pipeline installation.

　　8. When installing stainless steel pipes, do not use iron tools to strike. 9. For flanges connected to containers, equipment, and pumps, temporary asbestos blind plates shall be used during installation. For pipelines connected to dynamic equipment, the fixed welds shall be away from the equipment. After the pipeline installation is qualified, the dynamic equipment shall not bear additional loads outside the design.

　　10. Valve installation

　　(1) Before valve installation, the model shall be checked against the drawings, and the installation direction shall be determined according to the flow direction of the medium. Check whether the flange sealing surface is damaged. The operating mechanism and transmission device shall be adjusted as necessary. When welding valves, it is not advisable to close them.

　　(2) Protective measures shall be taken when installing regulating valves to prevent damage to instruments.

　　11. Installation of Supports and Hangers

　　(1) Supports and hangers should be fixed and adjusted in a timely manner. The guiding supports should be installed flat and firmly, and the sliding surfaces of the sliding supports should be smooth.

　　(2) The installation height of the springs in spring supports and hangers should be adjusted according to the design requirements and recorded.

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

　　(4) After the pipe installation is completed, the type and position of the supports and hangers should be checked one by one according to the drawings.

　　12. Temporary gaskets should be used at the pipe fittings and equipment that need to be removed during pressure testing and purging, as well as at the inlet and outlet of the pump. Formal gaskets can be used at other locations.

　　13. Backfilling of Underground Pipes

　　Underground pipes can only be backfilled after pressure testing, corrosion protection, and joint inspection are completed. Backfilling should be done manually in layers.

　　VII. Pressure Test

　　The following conditions must be met before the pipeline system test:

　　1. The pipeline system has been constructed according to the drawings, supports and hangers have been installed, and checked against the drawings

　　(1) Completed.

　　(2) Non-destructive testing is completed, and welds and other parts to be inspected should not be painted.

　　(3) The coordinates, elevation, slope, pipe base, and cushion layer of the underground pipelines have been checked and approved. Temporary reinforcement measures for the test have been checked and confirmed to be safe and reliable.

　　(4) All QC forms that should be filled out according to the quality plan and procedures are complete and have been approved by the QC department and relevant departments.

　　(5) The pressure gauges used for the test have been calibrated, with an accuracy of no less than 1.5 grade. The full-scale value of the gauge is 1.5-2 times the maximum pressure, and there are at least two pressure gauges.

　　(6) A pressure test system flow chart has been prepared, indicating the location of the pressure gauge and the parts that require blind flanges.

　　(7) The pressure test application form has been approved by the relevant departments. 2. Before the pressure test, systems, equipment, instruments, and pipe fittings that are not involved in the pressure test should be isolated, and the parts with blind flanges should be clearly marked and recorded.

　　3. Before the pressure test, check the process flow, open the relevant valves. If the flow direction of the test medium is opposite to the flow direction of the check valve, remove the valve core. The removed valve core should be labeled and recorded, and reinstalled after the pressure test and flushing.

　　4. Pressure Test Medium

　　(1) Considering the water source issue, it is recommended that low-pressure pipelines mainly use air pressure testing, supplemented by water pressure testing.

　　(2) If water is used as the pressure test medium for austenitic stainless steel pipes, the chloride ion content must be less than 50 ppm.

　　5. Test Pressure

　　(1) The water pressure test pressure is no 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 ASME .B31.3.

　　6. Pressure Test Steps

　　(1) When filling the water pressure test system with water, try to fill it from the bottom of the pipe, 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) Increase the pressure slowly. After reaching the test pressure, stop for 10 minutes. If there is no pressure drop and no visible deformation of the pipe, then reduce the pressure to the design pressure and conduct a comprehensive inspection of the pipeline system, including but not limited to welds, valves, and flange joints. If the pipeline system shows no leakage and no pressure drop after a comprehensive inspection, it is considered qualified. If leakage is found, the pressure should be released, and no operation should be performed under pressure.

　　(3) For air pressure testing, the pressure should be increased gradually. First, increase the pressure to 50% of the test pressure, and check all welds, valves, and flange joints. If there is no leakage or abnormality, continue to increase the pressure gradually by 10% of the test pressure until the test pressure is reached. Maintain pressure at each level for 3 minutes. After reaching the test pressure, maintain pressure for 5 minutes. If there is no pressure drop and no visible deformation, then reduce the pressure to the design pressure and check the welds, valves, and flange joints using soapy water. If there is no leakage and the pressure does not drop after 30 minutes of pressure holding, it is considered qualified. If leakage is found, the pressure should be released, and no operation should be performed under pressure.

　　(4) The safety requirements for pressure testing shall comply with the provisions in the safety procedures.

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

　　VIII. System Cleaning and Purging

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

　　(1) Prepare a system cleaning and purging flow chart, indicating the cleaning and purging direction and sequence.

　　(2) The pipeline system has passed the pressure test and been approved.

　　(3) Orifice plates, Venturi tubes, nozzles, filters, control valves, and flow meters on the pipeline system should be removed and replaced with short pipes.

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

　　(5) The system has been temporarily reinforced.

　　2. Water flushing should be continuous, with a water velocity of no less than 1.5 meters/second. The flushing discharge outlet should be as close as possible to the drainage well or ditch. If not specified in the design, flushing is considered qualified when the color and transparency of the outlet water are visually consistent with the inlet water.

　　3. Air purging uses industrial air or instrument air. Considering the air pressure and flow rate, purging cannot be continuous. Check the exhaust outlet with a white cloth or a wooden board painted with white paint. If there is no rust, dust, or other dirt on the wooden board, it is considered qualified.

　　4. Relevant personnel from the owner should participate in pipeline cleaning and purging. After completion, fill out the pipeline system cleaning and purging record.

　　IX. Pipeline System Reset

　　1. After the pipeline system pressure test is qualified, the pipeline should be immediately reset. The orifice plates, Venturi tubes, nozzles, filter screens, regulating valves, flow meters, check valve cores, etc., removed during the pressure test and purging, should be reinstalled according to the drawings. Blind plates added during the pressure test and purging should be removed, and all temporary gaskets should be replaced with formal gaskets.

　　2. For pipelines connected to dynamic equipment, the flange parallelism should be readjusted before resetting. The pipeline and equipment should be finally sealed and connected. Recheck that the radial displacement of the equipment connection shaft does not exceed the manufacturer's requirements; otherwise, readjust the pipeline until it is qualified.

　　3. Remove all temporary supports added during the pressure test and purging. Re-check and adjust all supports, hangers, and spring supports to meet the drawing requirements.

　　4. A pipeline system closure record should be completed after the pipeline system is reset.

　　X. Pipeline Corrosion Protection and Insulation

　　1. Underground Pipe Corrosion Protection

　　(1) After the pressure test is qualified, corrosion protection should be applied to all welds. First, use a grinder to remove rust and weld spatter from the weld area.

　　(2) Before backfilling the underground pipes, use an electric spark leak detector to check for leaks. Repair any damaged areas, and then re-check with the electric spark leak detector until it is qualified. After the owner approves the qualification, the electric spark leak detector inspection record should be filled out promptly.

　　2. Pipeline Painting

　　(1) After the pipeline pressure test is qualified, use a polishing machine to remove rust from welds and fittings. After approval by the relevant departments, the primer can be applied. On-site painting should generally be allowed to air dry. The time interval between multiple coats of paint should ensure that the paint is dry. The next construction process should not be carried out until the coating is fully dry.

　　(2) After the primer for welds, fittings, and pipes has been repaired, fill out the record promptly. After approval by the relevant departments, the topcoat can be applied.

　　3. The coating quality meets the following requirements:

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

　　(2) The coating is complete, undamaged, and without any omissions.

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

　　XI. Pipeline Insulation

　　1. Pipeline insulation can only be carried out after the pipeline system has passed the pressure test and painting.

　　2. Pipeline insulation materials must pass inspection before use. The insulation at valves and flanges should have a structure that is easy to disassemble and reassemble. The insulation layer should not hinder the replacement of packing.

　　3. The insulation construction of non-horizontal pipelines should be carried out 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, tight, uniform in thickness, and free of pores and cracks. After the insulation layer is inspected and qualified, the metal protective layer can be applied.

　　4. The metal protective layer should be pressed down and tightened, without any peeling or unevenness. The circumferential and longitudinal seams should be overlapped or interlocked, with the seams facing down. Self-tapping screws should be used for fastening, and the moisture-proof layer should not be punctured.

　　XII. Construction Quality Records and Inspection Reports

　　1. Construction quality records should be kept simultaneously with the construction, accurately and truthfully reflecting the construction situation. QC engineers and technicians should frequently check various records, and construction teams should have dedicated personnel responsible for record-keeping.

　　2. Inspection reports should be filled out by QC engineers, truthfully reflecting the inspection content and quality situation, and approved by the relevant personnel of the owner.

　　3. Construction quality records and inspection forms can be found in the pipeline system section of the quality plan.

　　XIII. Modification Notes

　　If it is found that this procedure cannot fully guarantee the completion of the project/new construction situations/new site conditions are encountered, or at the request of the owner, this procedure will be modified.