Engineering360: "This school's gas valve looked to be closed, then it exploded"

It was probably unwise for the maintenance worker to use a transmitter when gas was smelled. They don't allow transmitters around dynamite. Who in the school would be listening at his frequency?

1. There is no mention if the radio was intrinsically safe.

2. Transmission via radio was the most expeditious means of communication whether or not there were any listeners.

There was no mention of danger before most of the mass shootings either.

So your attitude is, I am going to transmit even if it kills me?

I seem to read you a lot Mr. Wagman.

My question would be what was determined to have been the ignition of the blast?

Was the radio a factor? The blast sites where they restrict the use of shortwave radios is done so because that is what they use to detonate the explosive, I think - please correct if I'm wrong.

On every large gas valve I have seen (and remember) there is this "witness mark" - a line indicating the position of the flow direction either through the valve or if perpendicular to the pipe indicating it's closed. Any Plumber of Pipe-fitter is aware of this rather important fact. On smaller valves they have a "fixed" handle which is known to indicate the flow (or not)of the fluid inside the pipe. Also I have a problem with the disassembly of the piping. If a pipe or fitting was loosened by unscrewing it would certainly begin to spew gas which should/would be an indication of the problem. then of coarse you would re-tighten it and proceed to get the gas turned off. Certain individuals should not be allowed to be in the position to cause this type of disaster. However I have seen this happen, but without the explosion part, on one of my last jobs as superintendent. Same "fitter" apparently hired from the "head down", caused 2 evacuations of same project by just being stupid.

But those valves large enough to have the "wrench" you mention as stated should be removed and attached nearby so as not to give the false impression of being closed. The "nut" on top of those valves is usually square so if the wrench is left in place it could either be closed or OPEN.

I was posting our insurance company's "required safety posters" in my construction office one day and our concrete contractor's superintendent offered this observation: You only need one poster - "NO DUMMIES".

I agree, Jim

The contractor was not competent to perform this work. The handle can of course be in any position on a plug cock, and is not determinate of the actual valve position. That is the bottom line.