On the basis of analysing welding property of P91 steel

a welding process for P91 steel pipes with large bore and wall thickness has been given

the operational parameters and matters to pay attention in the welding process

such as inspection and cleaning of the bevels

grouping bevels for position-welding

argon-filling protection from the back

preheating before welding

argon arc welding with manual tungsten electrode

filling and precoating with electric arc welding using electrode

as well as heat treatment after welding etc.

being put forward.