Richard wrote:
Ian Stirling wrote:
Richard wrote:

So, my 'magnets won't stick to stainless steel' test is flawed?


Yes.
Some stainless steel is magnetic, and some stainless becomes magnetic
after it is stressed.

Ah! Thanks for that. The offcuts that we tested are not particularly
shiny - which is what I'd expect for SS - and have the sort of rainbow
sheen that you see on steel tent poles. Would SS have been used on
pipes that never saw the light of day, even in days of copper scarcity?

I honestly have no idea.

SS occasionally has that sort of sheen.

If you own a blowtorch...

A small bit of it.
Galvanised will burn off with an whitish fume (don't breath it) when it gets
near red hot.

It's certainly not plain steel, as that would at least be showing some
evidence of rust.