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What are criteria for providing the bypass line in the control valve? In NG fuel line from 32 ksc to 5 ksc pressure drop at 70 deg C, can we provide the control valve bypass?
 
Answers
25/01/2015 A: chandrasekhar kurcharlapati, toyo engineering, k_chandra_sekhar@yahoo.com
You should not fuel gas line is catering to Pilot burners in Heaters.
For other cases HAZOP shall be conducted to decide.
22/01/2015 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
The purpose of a control valve bypass is to allow maintenance or replacement of the control valve without stopping the fluid flow. A globe valve is preferred for easier control by throttling. It is usually one size smaller than the main line size. During normal operation, the bypass should be completely closed for safety reasons.