【Daily Question 20090330】Discuss the issue of responsibility for equipment damage?

1. After an interlock shutdown, the machine shall not be restarted until the cause has been identified; generally, a two-out-of-two system is used, and the possibility of an instrument failure is low； 2. When large-scale units are restarted or brought online, relevant personnel should participate and carry out related interlock tests ； 3. After stopping due to shaft displacement, an inspection should be carried out, and the shaft displacement should be recalibrated.

After the plant stops due to interlock action, the cause should be investigated and confirmed. If the process is started blindly without resolving the issue, any accidents that result are the responsibility of the process team.

Generally, large-scale units shut down automatically due to high shaft displacement as a safety measure. Once a shutdown occurs as a result of this safety action, it is necessary to carry out the necessary preparatory tasks before restarting the unit. I. Analysis of the cause of the failure (organized and coordinated by the Maintenance and Production departments) 1. Check for equipment-related causes: Equipment maintenance personnel (under the supervision of the Maintenance department) conduct a detailed inspection of the equipment itself to determine whether the failure is caused by the equipment. 2. Check for instrument-related issues: The personnel responsible for the instruments (under the supervision of the mechanical department) conduct static tests on the instrument circuits to identify the problem, rule out any instrumental errors, and determine whether the issue is indeed caused by the instruments. 3. Check for process-related reasons: The process responsible personnel (under the supervision of the production department) analyze the process parameters at that time to determine whether it is caused by process issues. II. Fault Handling: Based on the above analysis, appropriate solutions are formulated to address the faults promptly. III. Preparation for startup: The startup process must be carried out strictly in accordance with the operating procedures.

1. First, as for the reasons: generally speaking, vibration signals measure alternating current components, which are prone to interference and generate false signals; whereas displacement measures direct current components, making it less susceptible to interference, so the likelihood of it being genuine is higher. It is theoretically incorrect to determine false signals based solely on short processing time and then start the machine directly. 2. Work procedures: It is important to remember that procedures are more important than techniques – this is the working philosophy. Judgments made by individuals based on experience are likely to be incorrect. Following the standard procedures (normally, the instruments are checked first, and only after it is confirmed that there are no issues will the dispatch team organize the restart) can help to prevent safety accidents to the greatest extent possible. 3. For such critical interlocks, a locking function can be implemented; once the interlock activates, the conditions are locked, and it is only possible to proceed after relevant personnel confirm and reset the system, which also helps to reduce errors caused by operators.

Don’t factories usually blame the instruments, equipment, and electrical systems when an accident occurs? :L

This reminds me of the discussions from a couple of days ago at http://bbs.hcbbs.com/thread-427475-1-2.html; at that time many people thought that pulse signals could be used for output, while I kept emphasizing that interlock outputs needed to have self-protection mechanisms

To assign responsibility, it is necessary to hold the person in charge of operating the vehicle accountable; allowing others to drive without resolving the issues is a management problem

It is entirely possible to stop the machine due to excessive shaft displacement. There is a problem with the pulse signals generated by the DCS per second. Firstly, the standard scanning cycle of the DCS is one second; this circuit may use rapid scanning, but the pulse width is not sufficient – it should be between 2 and 5 seconds. The process philosophy holds that it is incorrect to attribute the instrument readings to errors; instead, the primary cause of the unit shutting down should be identified, by checking the SOE records. It is entirely possible to determine the specific reason for jumping off the train. It’s definitely a problem to start the machine without notifying the instruments about the process; the cause must be identified, and the instruments should come up with solutions based on that cause before starting the machine is allowed. Additionally, once a large-scale unit shuts down due to interlocks, those shutdown conditions need to be reactivated or reset before the machine can be started again. If all these are in place but the process is not carried out, the responsibility lies with the process. My experience is that in factory operations, procedures are more important than skills; you cannot ignore the procedures and act as you please – you must follow them strictly. Otherwise, what’s the use of operating procedures?