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?
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.
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.