3 replies to this topic

[plonczak]

Recently I am having problems with a control valve which controls flow to a vacuum furnace, the question is can, I put a block and bypass valve to be able to remove the valve without stopping the plant? I have checked several design standards and there is nothing against it, and I have also seen other furnaces whit more sever conditions, and they have block and bypass valves on the flow control valves too the furnace. Right now I’m thinking to do the modification. Thanks for any comment and help

[fallah]

plonczak,

You should refer to the relevant project spec. Anyway, it normally depends on the size of the control valve as follows:

Small size control valves, let say up to 6", are equipped with block valves and by pass except in noncontinuous services.

Large size control valves, let say higher than 6", will be provided with hand wheel and not equipped with block valves and by pass. For main utility control valves (fuel gas and air), may be such as your case, by pass normally comprises a spare on line control valve.

Fallah

[plonczak]

Tanks for the information.

[S.AHMAD]

Plonczak
1. Installation of block valve and bypass is a common practice recognizing the need for onstream maintenance of control valves.
2. However, conduct an hazards analysis and risk assessment before doing the job so that we clearly understand the risk involved.
3. When we are doing onstream maintenance of a control valve, we are replacing auto control with manual control in the field (onsite). The associated risk will be depending on the process operations.

Edited by S.AHMAD, 05 March 2012 - 09:02 PM.