Model Forum / General / Models / April 2010

I have previously bemoaned the fact that MAPP gas is no longer available
- the Canadian factory/refinery which produced it partially shut down -
but I'm in B+Q because I need some M10 studding in a hurry and Lo! and
Behold!,  and they have something called MAPGas in 400g disposable
cylinders.

Now there are several so-called "substitutes" for MAPP gas, including
one made Rothenberger called MAPGAS (note the different capitalisations)
 so I wasn't hopeful.

Mostly these substitutes are simply proylene aka propene, which isn't
nearly as good as MAPP gas, you can't weld steel with it; MAPP was
Methyl Acetylene/Propadiene mix stabilised with Propane (and sometimes
Propene).

This is made by GoSystems however, and on the label it says:
methylacetylene and propadiene mixture, stabilised - I buy one.

Get it home, and burn a bit without oxygen - black floaters!

Haven't tried an oxy-mix yet, as I haven't got the correct fitting for
the top of the can, but I am one excited bunny :)

-- Peter Fairbrother

(this is only important for small-scale welders, but it means you can
gas-weld steel without acetylene - MAPP isn't quite as good as acetylene
for this, eg it can cause hydrogen embrittlement and you may have to
heat-soak the finished article - though in practice for the small welder
this is not a concern - but MAPP works, it's hot and energetic enough to
weld steel, unlike the so-called "substitutes")