The standard choice for MMA processing is actually stainless steel, because carbon steel/iron/etc scavenge the inhibitor used to prevent thermal runaway. HDPE would work, and often how it is transported in drums, but for actual processing, everything would normally be spec'd as stainless steel.

Which, of course, is pretty spark resistant to begin with.

Even if this wasn't true, this is not a hard problem, you can use non-sparking tools, proper coolant, lots of things to avoid sparks.

Or you know, we could require that highly flammable materials subject to thermal runaway have "drill here in case of emergency" patch of non-sparking material or something.

The cost of ATEX/Class 1 Div 1 compliance would not really go up if you required this.

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VTimofeenko 17 hours ago | parent [-]

Inb4: I don't work in the industry, my knowledge is limited to a faint memory of a college course on fluid dynamics.

If I recall correctly, high pressure ignitable stuff can spontaneously turn !!FUN!! in absence of heat if it is suddenly relieved through a pinhole. Basically jet is followed by a ring-like zone where the stuff mixes with oxygen. Jet creates tiny zones of very high temp, thus igniting the mixture ring that follows.

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DannyBee 8 hours ago | parent [-]

This is true in other cases but in this case they are actually hoping it leaks

	▲	VTimofeenko 4 hours ago \| parent [-]
		Maybe the thought process is that leak would effectively be pressure normalizing over a larger area and more gradually than creating a tiny hole, so whatever I said about jet ignition would not be applicable