The Japan Steel Works, Ltd.

Chiyoda Chem. Engineering & Construction Co.

Akiyoshi Fuji

Takao Adachi

Ryuichi Chiba

Keizo Ohnishi

Keizo Onishi

Katsuyuki Naitoh

Hachiro Okada

A method for overlay welding of stainless steel on the inner surfaces of pressure vessels as used for treating hydrogen at elevated temperature, e.g. below 450.degree. C. and under high pressure, e.g. below 150 kg/cm.sup.2, is provided wherein, in order to prevent the disbonding of the welded stainless steel, as the 1st layer weld overlay including martensitic structure of 4 to 40% by area or additionally including ferritic structure of up to 8% by area is used. For this purpose the chemical composition of the stainless steel weld metal is defined as essentially comprising of up to 0.1% C, up to 1.0% Si, up to 2.0% Mn, 7 to 12% Ni, 12 to 18% Cr, up to 1.0% Mo, and up to 0.1% Al, the balance being Fe. The stainless steel weld overlay may further include Nb of above 8 times the carbon content but up to 1.0%.

Welding method for stainless steel weld overlay

A welding method for stainless steel overlays is disclosed wherein a welded stainless steel overlay is prevented from exfoliating out of an inner surface of a high pressure vessel. Hydrogen exists at a partial pressure of less than 150 kg/cm.sup.2 and a temperature less then 450.degree. C. in the pressure vessel. At least one low alloy steel weld-overlay is preliminarily welded over the inner surface of the pressure vessel. The preliminarily low alloy steel weld-overlay is composed of similar composition to the base metal of the vessel, containing niobium and/or nickel. Thereafter, at least one customary ferritic steel or austenitic steel weld-overlay is welded thereon.

Method of welding for exfoliation prevention of stainless steel

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Muroran, Japan

Akiyoshi Fuji