Directing against the actual situation that a large amount of stainless steel pipelines should be welded during their erection in nuclear power plant construction

starting from ensuring the welding quality of weld-joint roots and reducing the construction cost

three argon-filling protection methods

i.e.using sponge and bakelite plate as plugs

using soluble paper as plugs

and using soluble paper to make an annulas air chamber with U type cross-section

have been compared and studied.practice shows that the said meaures not only can be used as argon-filling protection for the weld-joint roots of stainless steel pipelines

but also can be used as argon-filling protection for the weld-joint roots of various medium and high alloy steel pipelines.