Flux cored wire CO2 gas shielded welding is becoming more and more popular. FCAW is also common in pressure vessels or pressure pipes, but there is a lot of controversy both in terms of experience and theory.

Ocean engineering, the manufacturer used FCAW to do Φ168mm welding evaluation, passed the experiment, the third party directly approved the manufacturer's WPS coverage to the diameter Φ84mmX19mm.

There are two points of view for using FCAW for important pressure pipelines:

1. The pressure is too high, more than 1MPa (some international large project owners have similar restrictions), it is not recommended, because the industry recognized that the stability of flux-cored wire is a worldwide problem, no one manufacturer in the filament ( 1.2mm most commonly used in the field can guarantee that there will be no hollow, the problem of uneven powder is referred to "NBT 47015-2011 original JBT 4709".

2. Manual operation of the full position diameter Φ168mm is probably a lower limit. It is not excluded that individual good hands can reach the level of Φ89mm, but there is no promotion value, because it is difficult to master, as the diameter of the pipe becomes smaller, the operation difficulty increases, it is difficult to guarantee the quality.