Regarding process pipeline purging issues

File number: Preparation of technical plan for pressure testing and purging construction of medium and low pressure pipelines of the 1.5 million tons/year residual oil hydrogenation (VRDS) unit of the Qilu Refinery Renovation and Expansion Project: Chen Chunlin Construction Technology Review: Quality Assurance Audit: Security technology audit: Approval: Sinopec Group Tenth Construction Company Qilu Refinery Renovation and Expansion Project Project Department August 23, 1999 Qilu Refinery Renovation and Expansion Project 1.5 million tons/year residual oil hydrogenation (VRDS) unit medium and low pressure pipeline pressure test and purge construction technical plan construction unit: Approval: Sinopec Group Tenth Construction Company Qilu Refinery Renovation and Expansion Project Project Department August 23, 1999 Table of Contents 1. Project Introduction: The transformation of the 150×104t/a residual oil hydrogenation (VRDS) unit is one of the short-term and quick-release projects of the Qilu Refinery reconstruction and expansion project. The operating media are mostly high-temperature, hydrogen-prone, and toxic media. Due to the short shutdown time (only 2 months) of the device renovation, the construction peaks are concentrated, and the quality of the construction projects is high. In order to ensure that the pressure testing of low-pressure pipelines in the device transformation is completed in an orderly, fast, quality and quantity-safe, safe and efficient manner, this plan is specially prepared. The pipeline design for VRDS device renovation is divided into 17 areas. About 20,000 meters of new medium and low-pressure process lines have been added. The maximum operating temperature is 7.7MPa. There are many welded joints between old and new pipes in the equipment reconstruction pipeline, and the pipeline system intersects with each other in each zone. Therefore, the pipeline pressure test cannot be divided according to blocks, and the pressure test cannot be divided according to pressure, medium and system. 2. Basis for plan preparation: 2.1 Construction drawings and process system drawings provided by Sinopec Beijing Design Institute ； 2.2 "Construction and Acceptance Specifications for Pipeline Projects with Highly Toxic and Combustible Media in Petrochemical Industry" (SH3501-97) ； 2.3 "Code for Construction and Acceptance of Industrial Metal Pipe Engineering" (GB50235-97) ； 2.4 "Safety Regulations for Refining and Chemical Engineering Construction" (SHJ505-87) ； 2.5 "Regulations on Technical Documents for Project Construction Delivery" (SH3503-93) ； 2.6 "Quality Procedure Document" (QG/M44, 0000-99) ； 2.7 Construction organization design of 1.5 million tons/year residual oil hydrogenation (VRDS) reconstruction and expansion project ； 3.Construction sequence: Pipeline pressure test and purge construction sequence: Before the test, prepare for cleaning up the test process pipeline, inspecting the strength of the pipeline, restoring the purging system of the tightness test pipeline, and conducting a leakage test. 4. Process pipeline system test 4.1 Preparation before pressure test: 4.1.1 Test pressure range and test pressure confirmation: In order to improve work efficiency and reduce pressure test time, half-connect or large systems with the same pipeline materials, grades, and same (or similar) test pressures are tested. During the pipeline pressure test, all equipment that cannot participate in the pressure test must be system isolated. Equipment that cannot be isolated must be approved by the design and construction unit before participating in the system pressure test. Test pressure: For a connected system, the test pressure of the pipeline with the highest design pressure should be used as the test pressure of the entire system. However, this pressure value must not exceed the strength test pressure value of the series-connected equipment. Otherwise, the consent of the design and construction unit should be sought, and the strength test pressure value of the equipment should be used as the test pressure value of the system test. The hydraulic strength test pressure is 1 or 5 times the design force. ； When the pipeline design pressure ≤ 0. At 6MPA, the air pressure test can also be carried out. The air pressure strength test pressure is 1 or 15 times the design pressure. Effective safety measures (such as setting up a pressure test isolation zone, etc.) must be taken during the air pressure strength test and submitted to the project technical director for approval. The pressure gauge should be located at the highest point of the piping system. If it is insufficient, the actual value of the system pressure should be obtained by subtracting the hydraulic pressure between this point and the highest point from the pressure gauge reading here. 4.1.2 Conditions that must be met before pipeline pressure test: (1) The pipeline system construction is completed and meets the design drawings and specifications. ； (2) The pipeline supports and hangers are installed ； (3) The pressure gauge used for testing has been calibrated and passed the test. The accuracy is not less than level 1 or 5. The full scale value of the dial is 1. 5-2 times the maximum measured pressure. There are no less than 2 pressure gauges. ； (4) Prepare the equipment and materials needed to test your husband. 4.2.1 Test medium: The test media are water and air. The air should be clean urban compressed air without oil pollution. Use instrument air or urban compressed air first. The chloride ion content of the pressure test water for stainless steel pipelines shall not exceed 25MG/L. 4.2.2 Pre-test inspection: Organize the construction unit, design representative, and construction unit to conduct a three-party joint inspection of the test pipeline system. The joint inspection content includes: (1) Check whether the pipeline material, specifications, and wall thickness series meet the requirements of the drawings ； (2) Check the dimensions of pipelines, valves and components according to P1 diagram ； (3) Check the dimensions of pipelines and valve components according to the piping diagram ； (4) Check whether the position, quantity, type, size and quality of the pipe racks meet the requirements according to the piping diagram ； (5) Check radiographic flaw detection, surface flaw detection, and heat treatment conditions according to construction records. 4.2.3 Technical requirements for pressure test preparation: (1) Before the test, the equipment, instruments and pipeline accessories that cannot participate in the test should be isolated with blind plates, and the safety valves and blasting panels should be dismantled. ； Do not use valves to separate the two ends of the pipeline or in the middle, but insert blind plates. ； Set up isolation blind plates for running pipelines. When water and steam pipelines are isolated by valves, the temperature difference on both sides of the valve should not exceed 100 degrees. (2) All pipelines with spring supports and hangers must be temporarily supported or the stop blocks of spring supports and hangers inserted before pressure testing and water filling. After the pipelines pass the pressure test and the water is drained, all temporary supports and stop blocks of spring supports and hangers must be removed. ； (3) When the outdoor air temperature or water temperature is lower than 5 degrees, the water husband test will not be conducted (the temperature of alloy steel pipes shall not be lower than 15 degrees). (4) The added blind panels must be clearly marked and clearly located, and completely recorded in the flow chart for easy removal. ； (5) The technical personnel responsible for the pressure test before the pressure test should explain to the construction team according to the pipeline pressure test flow chart or line diagram, and the flow chart should indicate: System water inlet (gas) port, drainage (gas) port, high point deflation point, pressure test pump connection point, test medium flow chart, pipeline number, test pressure and blind plate insertion point, and pressure gauge setting location. (6) The inlet flow direction of pipelines with check valves should be consistent with the flow direction of the check valve. Otherwise, the valve core should be taken out or locked to the normally open position. (7) All instrument pressure-guiding pipes in the pressure test system should be isolated from the instrument or removed. When a union is installed between the instrument and the first shut-off valve, the union should be disassembled during the pressure test. 4.2.4 Test process (1) During the hydraulic test, the air in the system should be purged, and the pressure should be raised slowly. After reaching the test pressure, the pressure should be stopped for 10 MIN, then the pressure should be reduced to the design pressure, and the pressure should be stopped for 30 MIN. If there is no pressure reduction, no leakage, and no deformation, it is qualified. ； (2) Gas pre-test should be carried out before the air pressure test. The pre-test pressure should be taken between 0, 1-0 and 5MPA according to the test pressure. During the gas pressure test, the pressure should be increased gradually and slowly. When the pressure rises to 50% of the test pressure, stabilize the pressure for 3 MIN. If no abnormality or leakage is found, continue to increase the pressure step by step at 10% of the test pressure. Stabilize the pressure for 3 MIN at each stage until the test pressure is stabilized for 10 MIN and then reduce the pressure to the design pressure. Carefully inspect the system with soapy water. If there is no leakage, it is qualified. (3) For pipeline test pressures with design temperatures higher than 200 degrees, perform correction calculations according to the following formula: (4) If there is leakage during the pressure test, repairs under pressure are not allowed. The test should be repeated after the defects are eliminated. (5) After passing the pressure test, pressure test records will be made for the pipelines participating in the pressure test system. The quality inspection personnel of Party A and Party B will fill in and countersign the "Pipeline Strength/Tightness Test Record". (6) After passing the pressure test, the pressure should be slowly reduced and the test medium should be discharged to the designated location. (7) After the pressure test is completed, remove the temporary blind plates and temporary pipelines in the pipeline system. The valve closed due to pressure test should be placed in the operating position, and the connection between the instrument and the pressure pipe should be reset. (8) Pipelines that have passed the pressure test should be clearly marked to avoid confusion. (9) Pressure test system, pipelines, test pressure, etc. Table 1 5. Pipe purging and cleaning After passing the pipe strength test, purge and clean the work in sections. 5.1 What should be done before purging: 5.1.1 Remove the instrument, regulating valve, flow orifice plate, flow limiting orifice plate, flow H, water trap, safety valve, etc. ； 5.1.2 Remove the check valve core in the piping system ； 5.1.3 When steam and air are used for purging, attention should be paid to the backlash effect of the air flow at the outlet of the purge pipeline on the pipeline, and check whether the common support hanger is stable and reliable, otherwise it should be reinforced. ； 5.1.4 Place a blind plate for isolation at the equipment nozzle ； 5.1.5 Install temporary piping at the inlet and outlet of the purge system ； 5.1.6 The technician responsible for purging shall explain to the construction team according to the purging process. 5.1.7 Put a tag on the valve of the purge system and install an isolation belt at the purge outlet. 5.1.8 For pipelines that require target inspection, a clamp or fastening bolt pair for fixing the target plate should be installed at the outlet. 5.2 The basic components of the material pipeline are designed with a purge steam line, which can be directly purged with steam. ； The steam pipeline should be purged with steam. When purging the 3.2MPACMS steam line, the pipe rack should be reinforced at its steam outlet. The water pipe should be flushed with water, and other piping systems should be purged with air. For chemical cleaning and oil flushing of the oil system of the compressor and high-pressure pump body, see the compressor and high-pressure pump construction plan. 5.3 For air purging, the large vertical equipment in the device (such as C-1702, C-1500, V-1319, etc.) can be used as an air storage tank. Use compressed air or an instrument to see the air compressor, increase the pressure to 0, 3-0, 6MPA, and purge each pipeline according to the system. 5.4 The order of purging should be carried out in order of main pipe, branch pipe and drainage pipe. The dirt blown out shall not enter the pipes that have been purged. 5.5 The flow rate of purging medium should not be less than the following requirements: Water should not be lower than 4 or 5M/S, air should not be lower than 20M/S, and steam should not be lower than 30M/S. 5.6 Before steam purging, the pipes should be slowly warmed and kept at constant temperature for 1 hour before purging. Then, the pipes should be naturally cooled to the ambient temperature and then heated up, warmed, and kept at constant temperature for a second purge. Repeat this process until it is qualified. 5.7 When purging, prepare a few wooden bells and tap them gently on the outer wall of the pipe to flush and clean with the flow of media. 5.8 Purge Qualification Criteria: 5.8.1 After water dissection and cleaning, the pipeline system is deemed to be qualified if the water bag and transparency at the outlet are consistent with the water bag and transparency at the entrance. ； 5.8.2 The air or steam purged pipeline should be inspected with a white cloth or white-painted target at the outlet. If there is no rust, dust or other debris on the target plate within 5min, it is qualified. 5.8.3 For the MS steam line removed from the steam turbine, a target sheet should be installed for inspection after steam purging. The target sheet is generally an aluminum plate with a machined surface, 5 mm thick, with a width not less than 8% of the inner diameter of the exhaust pipe, and a length slightly larger than the inner diameter of the pipe. The target film shall be inspected according to the design requirements. If there is no provision in the design, follow the instructions in Table 2. MS line purge quality standards Table 2 Project quality standards The mark size on the target is Φ0. Trace paint below 6MM