butterfly valve safety question
butterfly valve safety question
(OP)
We are in the middle of a construction project and the construction company's engineer refuses to listen to our safety concerns about a 48 inch butterfly valve. The line on one side of the closed valve is full of sludge. The line for the other side of the valve has not yet been constructed. This side opens to a lower level full of expensive pumps and blowers. We asked that the construction company bolt a bar or something on the open side to prevent the valve from opening and flooding the basement and/or injuring one of our employees. The construction company's engineer scoffed at the idea the valve could fail or leak and will not have his people put a restraint in place. My question is are we out of line to ask for this safety step? Does anyone have experience with a valve such as this failing? Thanks for your advice.





RE: butterfly valve safety question
RE: butterfly valve safety question
For safety purposes, you can ask to the construction company to install a temporary blind flange on the downstream side of the valve. I have seen this practice in several hydroelectric projects.
RE: butterfly valve safety question
As for the seal failing, a blind flange would prevent leakage, at least until it is removed to extend the pipe. How much pressure is on the valve and what is it rated for?
Since there is sludge on the upstream side, I'd worry more about being able to open the valve when the time comes.
RE: butterfly valve safety question
Maury, the sludge is return activated sludge in a constantly mixed return box - not thick enough to settle out against the valve and prevent opening when the time comes. I do feel better no one thinks the valve or actuator will fail. We did remove the handwheel yesterday. We were thinking to be safe, we could fabricate a bar with pins against the plate that would bolt to existing bolt holes.
The valve is rated to 150 psig - The pressure on it will vary depending how many pumps are on line. We could have as many as four pumps on pumping up to 5 MGD each, but we are only using one in that line at 4 MGD for the time being. Obviously the flow is going through a common temporary line until the summer when work has been completed on the dry side of the valve.
RE: butterfly valve safety question
If the concern is inadvertent opening, then the above suggeston of using the lockout procedure, chaining, removal of handwheel, etc. are all good suggestions.
A blind flange will of course work also. But in this case, I think I am thinking like your construction contractor - it may be a bit overkill.
Even if the valve lets go, the amount of leakage is not so much a safety issue as it is a messy issue.
However, if you feel there is a safety risk, you need to follow your believe and get it blinded off.
RE: butterfly valve safety question
David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
The harder I work, the luckier I seem
RE: butterfly valve safety question
Does this butterfyy valve have a lock you have to depress in order to open the valve?
Good luck,
Latexman
RE: butterfly valve safety question
I appreciate your concern as over the years I've seen things that weren't supposed to happen, happen.
http://www.usaindustries.com/pipe_blinds.htm
RE: butterfly valve safety question
unclesyd, absolutely I agree with you.