Fusion Welding

[bulldog39]

Why is Propane (LPG) unsuitable as a fuel gas for fusion welding?

[control-arc]

Propane and natural gas are usually limited to heating and cutting because of its relative low temperature low heat flame

[Shane Kavanagh]

Hi, my understanding and this goes back to trade school days is that LPG has an oxidizing characteristic. With fusion welding using oxy you don’t want this. Using Oxy and acetylene you have control and can mix an oxidising flame, a neutralising flame and a carberising flame, by controlling the mixture at the torch and gas pressures from the regulators.

When setting up a flame for welding you try to get a neutral flame if not slightly carberised flame.

Any of the old timers that frequent this site should be able to confirm this or correct me, because it was only about 30 years ago all your pipe was welded this way before TIG became as widely used as it is today 🙂

Regards
Kav

Kav

[control-arc]

Carburising flame adds carbon to the weld metal and metal surface which depending upon application can lead to undesired hardening. It can be used for no ferrous materials and high carbon steels in which higher hardness levels are required.
Neutral flame is used for cutting and welding most steels
Oxidising flame Is used for welding copper based and zinc based materials and some cast irons.
The main reason propane lpg isn’t used, although it can be, is because it has a lower flame temperature and requires more oxygen to get a flame heat which is still cooler than the oxy acetylene flame. The cooler flame makes it slower and difficult to melt thicker materials.

[bulldog39]

Thanks for the reply. Much appreciated

[Author]

Posts