Scrutable

My great great grandfather was killed in a Welsh coal mine explosion in the 1890s. According to family tradition, he was identified based on what was left of his pocket watch.

Grumble wrote: Fri Dec 04, 2020 7:17 pm

OneOffDave wrote: Fri Dec 04, 2020 9:54 am Looking at the design of the silo, it doesn't look like it's designed as a pressure vessel and the damage doesn't look like a failed pressure vessel.

Thankfully I’m no expert on what a failed pressure vessel looks like, but the design looks like it could be meant to accommodate some pressure to me. Not a lot, sure, but any amount of pressure over ambient in a vessel that size would meet the criteria (250 bar.litres). The tank has clearly burst, but what the difference looks like between a burst from an explosion versus a release of over pressure I couldn’t say.

I'm possibly more of an expert on what a failed pressure vessel looks like than most on this site, and to me that looks like a standard atmospheric tank. It would be built to withstand ~20 mbars of pressure (1/50th of an atmosphere, or 1/3th of a psi for those who still deal with Imperial units); this is enough to withstand the most rapid atmospheric pressure changes allowing the tank contents to 'breathe' in and out through a vent, or if it's an oxygen-free tank though a (usually) nitrogen supply and outlet breathing valve (low pressure relief valve).

Looking at the pictures, this doesn't seem to be an explosion, or certainly not a large one, and the BBC reports that there wasn't any smoke involved, so if it was an explosion it didn't result in a subsequent fire (which would be unusual, but not unheard of), but the damage to the tank appears to be that the roof has been ripped off, with some damage to the sides at the roof join, but none apparent elsewhere, and no fire blackening on the exposed internal surfaces. The fact that fire engines attended doesn't necessarily mean that there was a fire.

Therefore, on the limited information available, I'd hypothesize that the explosion was an over-pressure build-up in the tank, rapid enough to not allow the over-pressure to be relieved via the facilities (and possibly any secondary relief device) and sufficient to cause the tank to fail at it's designed weak spot, which is the join between the tank sides and the roof.

What I'm more concerned with is that people were on top of the tank when this happened. My industry has a more cautious approach to safety and whenever anyone is on the roof of an atmospheric tank the tank is not operating and, preferably, drained of any hazardous material.

I'd forgotten this had happened but I was reminded by this story about the launch of a charity in memory of 16 year old Luke Wheaton who was killed. The end of the article says that an Avon & Somerset Police spokesperson said,

"An inquest into their deaths was opened by the coroner and has been adjourned pending the progress of the police/HSE investigation."

Does anyone know how long these sorts of investigations typically take? I know that we're not in typical times but a year seems rather a long time to wait. Especially as it doesn't even say that the investigations need to be completed, just "progress[ed]".

Fishnut wrote: Fri Dec 03, 2021 10:09 am I'd forgotten this had happened but I was reminded by this story about the launch of a charity in memory of 16 year old Luke Wheaton who was killed. The end of the article says that an Avon & Somerset Police spokesperson said,

"An inquest into their deaths was opened by the coroner and has been adjourned pending the progress of the police/HSE investigation."

Does anyone know how long these sorts of investigations typically take? I know that we're not in typical times but a year seems rather a long time to wait. Especially as it doesn't even say that the investigations need to be completed, just "progress[ed]".

So far, nothing has been published - two news articles: Bristol Cable and Bristol Post
The first is more critical of the lack of response and questions the time it's taken.