【Q&A Question 160】2016.09.27

(1) Before shutting down operations, proper organization for pipeline cleaning must be carried out, with each pipeline assigned to a specific person. (2) Ensure proper coordination for cable cleaning to strictly prevent wire cross-connections, injuries, or equipment failures. (3) Unified command should be exercised during line cleaning to ensure that the heavy oil pipeline has sufficient steam pressure, thus guaranteeing the effectiveness of the cleaning process. (4) Before introducing steam for scanning, the steam condensate must be completely drained, and steam should be introduced slowly to prevent water hammer. (5) In the sweeping step, heavy and solidifying oils are processed first, followed by light and non-solidifying oils. (6) Pressure must be maintained during line cleaning; for heavy crude oils, pressure needs to be kept constant repeatedly in order to achieve a good cleaning effect. (7) Before cleaning the lines, all meters must be bypassed and the steam must not pass through them. (8) During line cleaning, all connected lines, main and auxiliary lines, spare lines, dead ends, and other pipelines as well as control valves must be cleaned thoroughly; no dead corners are allowed to remain. (9) It is strictly prohibited to release oil vapor at any low-point vents during the line cleaning process; these vents should only be used to check the progress of cleaning and must be closed promptly. (10) After the scanning is complete, the scanning valve should be closed promptly, and the steam and condensate inside the equipment and pipelines must be completely drained. (11) Proper records must be kept during shutdown line cleaning; details such as the steam supply points, the times when steam supply is started or stopped, and the names of the operators should all be carefully documented to ensure accountability

(1) When stopping work for cleaning, care must be taken to avoid water hammer, pressure buildup, injuries, and the presence of dead corners. (2) After purging is complete, drain the water remaining in the pipelines and equipment containers. (3) The system is fed with liquefied gas to prevent freezing accidents caused by the heat absorption associated with vaporization.

1. When performing purging, the principle of \"starting with heavier fluids first and then lighter ones\" should be followed; heavy oil lines should be purged first, followed by light oil lines, to strictly prevent the solidification of heavy oils in the lines； Scan the back of the process first, then the front. The process before purging needs to be adjusted; the principle is to ensure that the backflow path is unobstructed (with the secondary lines or bypasses fully open) in order to minimize the resistance during purging. When introducing steam, all condensate water should be drained first; the steam supply should be increased gradually, and water hammer incidents must be strictly prevented. The amount of purge steam and the purge time should be controlled properly to save energy. 2. During purging, do not increase the pressure excessively; maintain the steam pressure in the pipeline network at no less than 0.6 MPa to ensure the quality of the purging process. Prolonged throttling operations must not be used; pressure buildup should occur intermittently, and the process should be carried out sequentially from front to back to ensure an adequate purging flow rate and to minimize steam consumption. The pressure of the cleaning steam should be higher than the pressure of the medium inside the pipeline being cleaned, to strictly prevent oil from mixing with the steam. 3. Before using steam to purge the gasoline system, it is necessary to first drain all the oil remaining in the system with water, reduce the pressure inside the system to atmospheric levels, and install appropriate blind flanges or disconnect the fittings to prevent pressure buildup or steam from entering the gasoline storage tank. 4. The vents of towers and vessels should have an appropriate opening to allow for the continuous drainage of condensate; the vents at the rear part should also be unobstructed to prevent pressure buildup. During one-way purging of the heat exchange equipment, a pressure relief mechanism must be in place on the other side (both the inlet and outlet valves of the tube side and shell side must be opened) to prevent damage to the equipment. During purging, the tube side and shell side of the equipment should be purged first, followed by the inlet and outlet bypass lines. When purging the cooler, all water remaining in the tube side must be drained, and the inlet and outlet valves for the tube side and shell side should be opened to prevent water hammer caused by steam condensation or pressure buildup resulting from the vaporization of residual water. 5. When purging all meters and control valves, contact the instrumentation department. The purging time for the pump body, control valves, rotameters, etc. should be as short as possible; the amount of steam used during purging should not be excessive. Glass plate level gauges must not be purged with steam, and after all liquid has been drained, the inlet and outlet stop valves should be closed. 6. During purging, all standby pumps, equipment that is not in use, dedicated lines for starting and stopping operations, auxiliary lines, and branch lines must all be thoroughly purged as well; no dead zones or hidden areas should remain. 7. Pump machines or other parallel equipment should be operated in rotation; the cooling water supply must not be interrupted while cleaning the pump machines. 8. The vent lines at the bottom of each tower and tank, as well as those at all low points, should be checked regularly to ensure they remain unobstructed. During purging, the condensate from various low points must not be discharged arbitrarily. After stopping the steam and releasing pressure, open the vent for inspection and drain any remaining water ； The drainage points on the framework must be connected to floor drains, while ground-level drainage must be directed into gutters. During the purging process, each pipeline to be purged should be inspected one by one to ensure it is thoroughly cleaned. Once the requirements for safe maintenance are met, the valve should be closed and the steam supply stopped, with proper records kept. 9. The “Ten No’s” principle: avoid producing defective products by reducing volume, prevent overpressure and overheating, avoid equipment damage caused by water hammer, prevent oil leakage and cross-contamination, avoid fires and explosions, ensure that no oil or water remains in pipeline equipment, and avoid delays. 10. For two \"one-time\" operations: the pipeline purging must be successful once, and the gas analysis of the container must meet the requirements for welding once.

1. Organize the wiring cleanup work before shutting down operations; assign each pipeline to a specific person, take strict precautions to avoid wire cross-connections that could cause injuries or equipment failures, and ensure unified command. 2. Before introducing steam, all steam condensate must be drained; steam should be introduced slowly to prevent water hammer. 3. Heavier oils and oils that are prone to condensation should be introduced first, followed by lighter oils that are less likely to condense. 4. Pressure must be maintained during line cleaning; for heavier oils, pressure needs to be maintained repeatedly. 5. All measuring instruments should be connected to bypass lines, and all connection lines, bypass lines, spare lines, control valves, etc., must be thoroughly cleaned. 6. During line cleaning, it is not allowed to release oil vapor at any low points. 7. After line cleaning is complete, the cleaning valves must be closed promptly, and all steam and condensate in the equipment and pipelines must be drained. 8. Records of all activities during line cleaning must be kept

First, purge the heavy oil pipelines, then the light oil pipelines; ensure that no oil remains in the pipeline equipment and that all water is completely drained. During the line sweeping period, the use of fire and open flames is strictly prohibited; oil and gas must not be released indiscriminately to prevent fires and explosions. The small amount of oil released was promptly washed away with water, and the area was cleaned up. Scan one line at a time and turn off one line to prevent missed scanning.

(1) When stopping work for cleaning, care must be taken to avoid water hammer, pressure buildup, injuries, and the presence of dead corners. (2) After purging is complete, drain the water remaining in the pipelines and equipment containers. (3) The system is fed with liquefied gas to prevent freezing accidents caused by the heat absorption associated with vaporization.

(1) When stopping work for cleaning, care must be taken to avoid water hammer, pressure buildup, injuries, and the presence of dead corners. (2) After purging is complete, drain the water remaining in the pipelines and equipment containers. (3) The system is supplied with liquefied gas to prevent freezing accidents caused by the heat absorption associated with vaporization

(1) When stopping work for cleaning, care must be taken to avoid water hammer, pressure buildup, injuries, and the presence of dead corners. (2) After purging is complete, drain the water remaining in the pipelines and equipment containers. (3) The system is fed with liquefied gas to prevent freezing accidents caused by the heat absorption associated with vaporization.