ESD Valves without Limit Switches

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Anonymous Poster #1	ESD Valves without Limit Switches 10/02/2011 7:13 AM
	Hi All, Are there still plants which uses ESD valves without the limit switches. I came across an oil & Gas stabilization and separation plant, Which is having ESD valves for the inlet of crude from the wells via manifold. The SCADA system does not have the feedback of the position of the valves. And I had a chat with the operator of the plant to confirm that during emergency situation they go to the valve to confirm the status of the valve. Normally they blindly believe that valve is shut down. The safety of the field operator is in toss... They say that they have done a detailed HAZOP study and the safety is the main concern for the plant..But how can they miss out basic safety implementation while doing HAZOP. And the most funny thing in this design is that the plant does not have and Emergency shut down Pushbutton.. Are there plants in these days have these type of design in place. Please discuss on your experience whether there are ESD valves are used without open/close feedback not reporting to the control room.
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sabriahmad Commentator Join Date: Nov 2009 Posts: 78 Good Answers: 9	#1 Re: ESD Valves without Limit Switches 10/02/2011 11:22 PM
	This is probably an old design and coupled with simple plant I still remember with the plant that I used to work in late 70ties. What we have are block valves at the battery limit that outside operator will shut the valve manually to cut-off main supply to the process units during emergency. The critical ones such as fuel supply to furnace or boiler have push bottom at control room. So, if someone conduct HAZOPS in this plant, ESV at battery limit will be one of the recommended "safeguard" item. Whether to install on/off indicator in the control room is not part of HAZOPS recommendation, it is the responsibility of the project/instrument engineer which are sometimes subjected to budget constraints and management philosophy. One way to justify such implementation is to conduct Layer of Protection Analysis (LOPA) a semi-quantitative method of risk assessment.
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Anonymous Poster #1	#2 Re: ESD Valves without Limit Switches 10/03/2011 2:21 PM
	Layer of Protection Analysis (LOPA) ..- Hearing it for the first time...Will start a search on it.. Thanks for sharing your experience.....I learnt something new today...Thanks.. Cheers
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