Butt welded tubular structure of austenite stainless steel

A butt welded tubular structure, comprising:

• two tubular members of austenite stainless steel butt welded together at their adjacent ends to form a welded joint and weld heat affected zones immediately adjacent said welded joint;
• and
• a restraining member providing a cover to said welded joint and heat affected zones of said tubular members in a manner to substantially form a clearance between the restraining member and the tubular members, said restraining member being formed of a metal of lower stress corrosion cracking sensitivity than the material of said tubular members, said restraining member being joined at the entire surfaces of opposite end portions thereof to said tubular members by welding performed while effecting cooling by directly bringing a cooling medium into contact with inner surfaces of said tubular members so that said tubular members and welded joint between the opposed end portions of said restraining member will be compressed and said restraining member will be under tension when said tubular structure is at substantially the same temperature after welding and cooling, said restraining member being spaced from said welded joint and said heat affected zones to form an annular chamber between said restraining member and said welded joint and heat affected zones of said tubular members.

A butt welded tubular structure, comprising:

• two tubular members of austenite stainless steel butt welded together at their adjacent ends to form a welded joint and weld heat affected zones immediately adjacent said welded joint;
• and
• a restraining member providing a cover to the entire outer circumferential surfaces of said welded joint and said heat affected zones of said tubular members in a manner to substantially form a clearance between the restraining member and the tubular members, said restraining member being formed of a metal of lower stress corrosion cracking sensitivity than the material of said tubular members, said restraining member being joined at entire surfaces of opposite end portions thereof to said tubular members by welding performed while maintaining said restraining member at a higher temperature than said tubular members so that said restraining member is under tension and the adjacent portions of said tubular members are compressed when said tubular structure is at substantially the same temperature after welding and cooling, said restraining member being spaced from said welded joint and said heat affected zones to form an annular chamber between said restraining member and said welded joint and heat affected zones of the tubular members.

A butt welded structure, comprising:

• two tubular members of austenite stainless steel butt welded together at their adjacent ends to form a welded joint and weld heat affected zones immediately adjacent said welded joint;
• and
• a restraining member providing a cover to the entire outer circumferential surfaces of said welded joint and heat affected zones of said tubular members, said restraining member being of a dual construction and including an inner portion facing said tubular members and formed of a metal of lower stress corrosion cracking sensitivity than the material of said tubular members, and an outer portion separate from said inner portion, remote from said tubular members and formed of a metal having a lower coefficient of thermal expansion than the material of said tubular members, both said inner portion and outer portion of said restraining member being joined at the entire surfaces of opposite end portions thereof to said tubular members by welding in a manner to substantially form a clearance between the restraining member and the tubular members so that the restraining member is spaced from said welded joint and said heat affected zones to form an annular chamber between said restraining member and said welded joint and heat affected zones of the tubular members.

A butt welded tubular structure, comprising:

• two tubular members of stainless steel butt welded together at their adjacent ends to form a welded joint and weld heat affected zones immediately adjacent said welded joint;
• and
• a restraining member providing a cover to the entire outer circumferential surfaces of said welded joint and heat affected zones of said tubular members in a manner to substantially form a clearance between the restraining member and the tubular members, said restraining member being formed of a metal of lower stress corrosion cracking sensitivity than the material of said tubular members and split into two portions arranged axially of said tubular members, said two portions of said restraining member being joined at the entire surfaces of opposite end portions thereof, which are not juxtaposed against each other, to said tubular members by welding and then joined at the split end surfaces thereof by welding, said restraining member being spaced from said welded joint and said heat affected zones to form an annular chamber between said restraining member and said welded joint and heat affected zones of the tubular members.