【Q&A Question 151】May 31, 2017
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This post was last edited by 955559 on 2017-7-21 22:49. [Q&A Question 151] May 31, 2017: What are the precautions for scanning? The reference answers can be seen after *replying*; points will be awarded if the key points are answered correctly. (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) :(1). When purging the lines, open the drain valves of each tower and container. (2). Before purging, close all orifice plate conduits as well as the side lines connected to the oil gauge. (3). When using steam for purging, make sure to drain all condensate water first; in winter, after purging with steam, use air to blow out any remaining water in the pipes. Open the drains or flanges in low-lying areas to drain the condensate and prevent freezing. (4). When using air to purge hot oil lines, the temperature of the oil in the pipes and containers must be 20 degrees below the flash point of that oil to avoid explosions and fires. (5). For pipes with high oil viscosity, it is necessary to first use steam for purging before resorting to air. (6). After the plant stops operating, purging must be carried out promptly without delay. (7). To ensure that the pipes are thoroughly cleaned, close the end valves, build up pressure, then open them again—repeating this process 3–5 times—to guarantee the quality of the purging. (8). Keep thorough records to avoid any omissions; assign someone responsible for each pipe, and submit the purging records to the workshop. Scoring criteria: 2 points for incorrect answers; 3–8 points for partially correct answers; 10 points for correct answers accompanied by detailed explanations; 15–20 points for correct answers with additional supplementary information. Please score according to these criteria. Note: If there are editing records after answering, only those who participated will be given points. For continuous malicious spamming, 2 points will be deducted each time, with no upper limit. Pure numbers, pure emojis, or random letters unrelated to the answer are all considered malicious spamming; points will start to be deducted after three warnings. 2017 Q&A Summary Thread (updates starting now) http://bbs.hcbbs.com/thread-1657793-1-1.html 2017 Daily Question Summary Thread (updates starting now) http://bbs.hcbbs.com/thread-1657794-1-1.html 2016 Q&A Summary Thread (updates completed) http://bbs.hcbbs.com/thread-1597792-1-1.html
(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 during vaporization.
1. No one should stand at the opening. 2. Follow the process. 3. Open the valve slowly
(1) Organize the work of cleaning the pipelines before shutting down operations, assigning each pipeline to a specific person. (2) Ensure proper wiring coordination 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 thickening oils are processed first, followed by light and non-thickening oils. (6) Pressure must be maintained during line cleaning; for heavy crude oils, pressure needs to be maintained repeatedly in order to achieve a better cleaning effect. (7) Before cleaning the lines, all meters must be bypassed and switched to the auxiliary lines; steam must not pass through the meters. (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 line cleaning is completed, the cleaning valve should be closed promptly, and all steam and condensate in the equipment and pipelines must be drained. (11) Proper records must be kept during shutdown line cleaning; details such as the steam supply points, the times when steam supply is initiated 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 during 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 the 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 heat absorption during vaporization.
1) Adhere to the principle of draining condensate first and then introducing steam; the introduction of steam should be done slowly. Once steam is observed at the outlet, the steam flow rate can be increased gradually, with strict attention to preventing water hammer. In the event of water hammer, the steam flow rate must be reduced immediately, or even stopped, until the pipeline stops vibrating. After the water hammer stops, dehydrating and introducing steam should be carried out following the principle of first introducing a small amount of steam to establish flow, removing condensate, and warming the lines, followed by a small amount of purging. (2) During the purging process, a dedicated person must be assigned to monitor the discharge outlet; it is strictly prohibited for the purging steam to pass through the pump body, and overpressure in the equipment and pipelines being purged is also strictly forbidden. (3) Since the pipelines are heated during steam purging, it is strictly prohibited to increase the steam flow rate rapidly after introducing steam. This is to avoid sudden thermal expansion of the pipelines, which could cause them to push forward; without enough time for compensation, this expansion may lead to buckling of the pipelines. It can also result in water hammer, with consequences such as the detachment of pipe supports, deformation of the pipelines, fragmentation and removal of the insulation layer, cracking of welds, and separation of gaskets. (4) Steam must be introduced into the equipment slowly, with a preheating process, to prevent uneven expansion of the heated equipment due to sudden temperature rises, which could lead to leaks. (5) Cold exchange equipment is generally not involved in purging; if purging is necessary, its inlet pipeline must first be thoroughly purged. When the purge medium flows in one direction, the other side must be opened to vent, to prevent leakage in the heat exchanger. (6) After the steam purging is completed, the low-point and high-point vents of the system should be opened to prevent steam from condensing, which could create negative pressure in the system and damage the equipment.
(1) When purging the lines, open the drain valves of each tower and container. (2) Before purging, close all orifice plate ducts as well as the oil gauge side lines. (3) When using steam for purging, make sure to drain all condensate water first; after purging with steam in winter, use air to blow out any remaining water in the pipes. Open drains or flanges in low-lying areas to drain condensate and prevent freezing. (4) When using air to purge hot oil lines, the temperature of the oil in the pipes and containers must be 20 degrees below the flash point of that oil to avoid explosions and fires. (5) For pipes with high oil viscosity, it is necessary to first use steam for purging before resorting to air. (6) After the plant is shut down, purging must be carried out promptly without delay. (7) To ensure that the pipes are thoroughly cleaned, close the end valves, build up pressure, and then open them again, repeating this process 3–5 times to guarantee the quality of the purging. (8) Keep thorough records to avoid any omissions; assign someone responsible for each pipe, and submit the purging records to the workshop.
1) When purging the lines, open the drain valves of each tower and container. (2) Before purging, close all orifice plate conduits as well as the oil gauge side lines. (3) When using steam for purging, make sure to drain all condensate water first; in winter, after purging with steam, use air to blow out any remaining water in the pipes. Open the drains or flanges in low-lying areas to drain the condensate and prevent freezing. (4) When using air to purge hot oil lines, the temperature of the oil in the pipes and containers must be 20 degrees below the flash point of that oil to avoid explosions and fires. (5) For pipes with high-viscosity oil, it is necessary to first use steam for purging before resorting to air. (6) After the plant is shut down, purging must be carried out promptly without delay. (7) To ensure that the pipes are thoroughly cleaned, close the end valves, build up pressure, and then reopen them—repeat this process 3–5 times to guarantee the quality of the purging. (8) Keep accurate records to avoid any omissions; assign someone responsible for each pipe, and submit the purging records to the workshop.
I’d like to state first that it was copied from the Internet. However, I went through each item carefully, treating it as a learning experience*: lol 1. During purging, one person designated by the Production Technology Department shall take overall command and make unified arrangements; 3–5 additional people should be stationed along the route to promptly identify and report any issues found, as well as to handle them. 2. When introducing medium and high-pressure steam, operators must wear the appropriate personal protective equipment as required. The personnel responsible for the pipeline systems in the utility room should operate the valves carefully; when using medium and high-pressure steam to warm the pipelines, it is essential to do so slowly. Drain valves should be activated along the pipelines to prevent water hammer, as well as leaks that may occur due to uneven heating of the pipelines and flanges. 3. Pay attention to whether the medium discharge volume is normal. Check that the expansion displacements of compensators, steam traps, pipe supports, hangers, slides, etc. are within the acceptable range. Inspect the pipes for any large debris inside; if any abnormalities are found, stop the steam supply immediately and report the issue to the workshop for handling. 4. When the pressure reaches 1.5 MPa and cleaning is to be carried out, in order to avoid impacting the medium-pressure steam network, the main valves of the utility piping system in the utility room must be closed (or reduced to a lower setting) before cleaning can proceed. 5. Cross operations are strictly prohibited in the vicinity of the purging port. When carrying out disassembly and assembly operations, it is necessary to wait until the pipeline temperature drops to room temperature before proceeding. 6. Assign dedicated personnel to monitor the steam inlet and outlet points, maintain communication, set up warning barriers, inform nearby workshops, and take appropriate protective measures. 7. After purging is complete, drain all the condensate from the lowest points of the equipment and pipelines. 8. After the line cleaning is complete and the temperature has dropped to normal levels, restore the (official) orifice plate and check for leaks at the flanges.