Single Block & Bleed - minimum bleed line size?

[Kaplin]

I have a 600psi 8" hydraulic line that is isolated using a single block and bleed. There are concerns that the existing 1/2" bleed line is too small. Are there standards that dictate the minimum bleed line size?

 

[00098]

There are regulations with regard to pipeline isolation. Depending where (state, province, country, etc)the system is located, the regulations vary. Usually worker safety boards predicate the regulations. I would contact the juridiction that regulates worker safety.
My gut feel is that the 1/2" bleed valve is too small.

 

[Kaplin]

I am in BC, Canada. I just looked at the WCB OSH standards and it only talks about the bleed line for a double block and bleed system (where the bleed has to be the same diameter as the main line). I agree - 1/2" seems small.

 

[samuelliu]

Requires 3/4" at least as per Table 1, MSS-SP-45.