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Flame shot out of Galvanized Pipe Handrail when drilled

June 19, 2012

Q. While drilling a hole in a galvanized pipe handrail, I had a flame shoot from the hole upon penetration. Have you heard of this before? What causes this to happen? Are there any warnings about this out there?

John Rabbitt
- Bellevue, Michigan, USA

June 22, 2012

A. After having galvanized thousands of tonnes of handrail pipe for many customers, have never heard of this before. For a flame there needs to be three things.

Fuel (presumably a gas in this case?)
Oxygen (air)
Ignition (your drill bit red hot?)

The air and possibly the drill are explainable, but what was the fuel?

What colour was the flame? That can be a clue to fuel type. For example a colourless almost invisible flame might be hydrogen? A sooty black flame might suggest acetylene ... and so on.

There isn't an obvious (to me) mechanism for producing a combustible gas inside a galvanized pipe by accident. If you put a strong acid in there (say hydrochloric) then the coating (zinc) would produce hydrogen. But you'd surely know if you added acid to the pipe?

Geoff Crowley
Crithwood Ltd.
Westfield, Scotland, UK
crithwood logo

A. Hydrogen build up inside the sealed galvanised handrail. Ignites when hole is drilled due to hydrogen & oxygen mix requiring very low input of energy to ignite (e.g. slight spark or perhaps the heat from the drilling)

Ken Allan
- Farnham,Surrey, UK
June 27, 2016

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