"A separate high liquid level monitoring, alarm, and interlock control system should be installed\" Question
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Hello everyone, I have a question. Recently, the local work safety supervision agency inspected the crude oil storage tank area and stated that there were no high liquid level alarms or interlocks in place. I checked the standard AQ3036-2010, clause 6.3.7: For combustible liquid storage tanks with a capacity of over 5,000 m3, and for pressure storage tanks containing hazardous chemicals with a capacity of over 400 m3, separate high-high liquid level monitoring, alarm, and interlock control systems must be installed. ”Questions arose: is it necessary to install a separate level gauge for high-level alarms, with the interlocks being implemented using a PLC? ； Is it still necessary to install another set of high-level level gauges and another control system for interlock purposes (ESD)?
I don’t know the original liquid level measurement device of the tank. If there is a control system, only one additional level gauge is needed to meet the requirements for measurement and high-alarm high-high interlock.
In other words, it is necessary to have a set of interlocks that operate independently of the existing system
If there is an existing SIS system, interlocks can be added to it; if not, a separate SIS system needs to be installed
If there was only one level gauge originally, then another one or a high-level switch needs to be added. The interlock system will work fine as long as it is connected to the existing SIS. According to a certain safety supervision agency, the SIS for the tank farm should be separate from the SIS of the production facilities and cannot be shared; how can companies afford such a setup?
It only involves activating the high-level alarm interlock; there is no need for a separate PLC or ESD – it can be handled entirely within the DCS
The intended meaning of the original text is: 1. In addition to the existing level gauge used for displaying the liquid level, another level gauge should be installed in the tank area for alarm and interlock purposes. 2. In addition to the existing DCS system used for production control, another interlock control system can be installed; it can be called ESD or SIS either.
It’s simply a matter of pulling down one’s pants and farting; the safety supervision agencies don’t want to take any responsibility at all. The more systems there are, the greater the risks if maintenance can’t keep up
sIs needs to be set up separately, independent of the DCs system.