PSV Discharge Gate Valve Stem Orientation 1

[MikalT]

It is good practice on PSV discharge block valves (closed systems) to orient the gate valve handwheel stem either horizontally or below horizontal (horizontal discharge line installations). There have been instances where the gate valve wedge has separated from (broken off of) the valve stem, consequently blocking the relief path.

My problem is... I can't find verbage to back up this common practice. Is anyone aware of a blurp in API RP-520 or anywhere else that may recommend this gate valve stem orientation?

Thanks!

 

[MikeClay]

Try API 520 Part 2 Paragraph 4.3.

--Mike--