Production Technology [Weekly Topic]: Accident Analysis (10-11-08~15)
Thread Content
This post was last edited by shmily327 on 2010-11-15 at 10:07. Workers such as Ding and Li from the instrumentation team went to the site to deal with the leakage in the thermometer gasket. Maintenance begins after the process operator confirms that the pipeline is pressure-free and empty. During the maintenance work, the operator warned the instrument technicians to move away. As they moved away, hydrogen gas leaked from the pipelines, causing an explosion that burned Ding’s hands, legs, face, and feet, as well as Li’s hands and feet. Please analyze what caused the accident What are the violations committed by the workers? How can we prevent similar accidents from happening again? Remarks: 1. Participation is rewarded ； 2. Please hide your replies; for instructions, see: http://bbs.hcbbs.com/thread-492556-1-1.html. 3. Do not edit your replies after posting them. 4. The moderator will announce the answers in a timely manner. 5. Correct answers with thorough and reasonable analysis earn +1 charm. Cause of the accident: 1. Inaccurate verification by the operator; the pipeline was not properly depressurized and purged. 2. Improper operation by the operator led to hydrogen leakage, which caused an explosion due to static electricity. 3. Inadequate coordination between operators and instrument technicians. Violations: 1. Failure to depressurize and purge the area where work is being carried out. 2. No analysis was performed. 3. The operator violated the pressure relief procedures by proceeding with the operation before the instrument technicians had retreated to a safe area. Precautionary measures: 1. Strictly follow the safety permit procedures. 2. When working together in a group, it is important to pay attention to communication and coordination.
This post was last edited by shmily327 on 2010-11-8 09:44. The standard maintenance procedure is as follows: 1. The process engineers issue the work order for the pipelines and equipment to be taken out for maintenance. It mainly includes: equipment isolation (using blind flanges or disconnections), pressure relief, purging, analysis, safety precautions, and assigning personnel (specific individuals) to monitor the process. If welding is required, a welding permit must also be obtained. In the above example, there is no isolation, no replacement or analysis, and no safety measures at all.
This post was last edited by shmily327 on 2010-11-8 09:45. Cause of the accident: Failing to cut off, evacuate, replace, and analyze the area to be repaired before carrying out maintenance work was the direct cause of this accident. What violations were committed by the operators: 1. The process technicians failed to carry out cutting off, draining, purging, and analysis as required by the maintenance procedures; they also failed to issue maintenance operation tickets and obtain sequential signatures for approval in accordance with the established process ； 2. The instrumentation personnel did not issue an instrumentation maintenance work order; they carried out the work blindly after only receiving verbal confirmation from the process personnel ； 3. Inadequate labor protection. 4. Employees lack awareness of safety during maintenance work. How to prevent similar accidents from happening again: 1. Raise employees’ awareness of safe maintenance practices. 2. Strictly follow the maintenance operation procedures, ensuring that process isolation, evacuation, and replacement are carried out prior to maintenance to meet the required standards. 3. The relevant maintenance personnel must strictly follow the applicable maintenance procedures. 4. Strict use and wearing of protective equipment.
Due to the limited details, the main reasons for the accident could be: 1. The pipeline was not isolated and gas replacement was not carried out； 2. The instrument technician carried malfunctioning instruments and electronic devices, or damage occurred during departure, or they were not wearing anti-static work clothing. 3. The Safety Supervision Department is in place. Illegal actions by operators: 1. Failure to obtain an operation ticket ； 2. Safety measures not learned* ； 3. No isolation or gas displacement was carried out ； 4. Carry failure-indicating instruments and electronic devices ； 5. Not wearing anti-static work clothes ； 6. There are too many miscellaneous items at the site, which were not cleared before starting work. Precautionary measures: 1. Strictly manage operation tickets; work is strictly prohibited without a ticket ； 2. Safety supervision must be ensured; the principle of \"one measure and one form of supervision for each project\" should be adhered to” ； 3. Strengthen training and safety education to improve employee competence.
Cause of the accident: The direct cause was that the operator failed to thoroughly isolate the maintenance area from the production area (through measures such as purging, using blind flanges, or valves), while the indirect cause was an explosion resulting from static electricity sparks generated by the leak. Violations: Firstly, neither the process workers nor the maintenance personnel followed the maintenance procedures nor obtained the necessary maintenance tickets. Secondly, no appropriate safety measures were taken to isolate the maintenance area from the production area (such as using blind flanges or informing other relevant personnel). Solutions: Firstly, it is necessary to strictly enforce the maintenance procedures and ensure proper use of maintenance tickets. Secondly, specific safety measures must be established during maintenance activities, along with corresponding training and communication to all relevant personnel
This post was last edited by shmily327 on 2010-11-8 at 10:53. Process operators should isolate this work area from the system, ensure that the analysis is satisfactory, and take appropriate safety measures; when working with instruments, they must wear protective equipment such as masks to guarantee safety during the work.
1. The cause of this accident was the technician’s violation of safety procedures. 2. The technician failed to obtain a work permit; the field operators did not install blind flanges on the pipelines, and nitrogen purging was not carried out before working on the hydrogen pipelines. 3. Most importantly, all employees need to have a strong sense of safety. Strictly enforce the work permit system; both parties must sign to confirm it, and when installing or removing pipelines for flammable and explosive liquids (gases), the isolation and purging procedures must be strictly followed
The operator confirmed that it was unqualified, as the medium inside the pipeline had not been replaced. I’m not sure if there was a work order signed for confirmation. It is essential to ensure thorough verification for maintenance work; carry out the necessary replacements and analyses, and enhance safety awareness as well as compliance awareness.
1. No confirmation from security personnel received； 2. No cleaning or replacement was performed ； 3. The relevant personnel were not notified to stop feeding material. The workshop makes unified arrangements, and operations are carried out carefully in accordance with the maintenance procedures.
1. Before maintaining pipelines that transport flammable or explosive gases or liquids (especially when hot work is involved), it is necessary to purge the pipelines with inert gas and conduct tests for flammable gases; work can only proceed once these tests yield satisfactory results. The accident was mainly caused by an explosion resulting from the presence of residual combustible gases in the pipeline where the thermometer was located, due to the process of replacing that pipeline. 2. The main violations include: operators performing pipe replacement, and inspectors taking samples on site to analyze their flammable components. 3. It is necessary to establish a unified work management system, strictly enforce the work order and operation order systems, and provide enhanced training for personnel on site.