To reduce the number of parts and to shorten working hours of transportation, installation, disassembly and removal, by devising a good way for positioning by use of a jig in welding.
A welding jig for a tank welded structure includes: an expander 2 which has a groove where a tube 4 can be inserted and removed in the circumferential direction of a body part 1 on an internal circumferential surface and is composed of a first expander portion 2a, a second expander portion 2b, a third expander portion 2c, a fourth expander portion 2d, a fifth expander portion 2e, and a sixth expander portion 2f, which are provided in the circumferential direction of the body part 1 to be attached to and detached from the internal circumferential surface of the body part 1; and a tube 4 which is longer than a circumference of the internal circumferential surface of the body part 1, is shaped like a ring without an end part, is capable of being inserted into and removed from the expander 2 in the circumferential direction of the body part 1, and is expanded in a complete circle by injection of pressurized air 5a in the radial direction of the body part 1 to press the expander 2 to the outside in the radial direction of the body part 1. The number of parts can be reduced and working hours of transportation, installation, disassembly and removal can be shortened by using the welding jig for the tank welded structure.
WATANABE DAISUKE
Tadahiro Mitsuishi
Mitsuishi Shunpei
Yasuyuki Tanaka
Hiroshi Matsumoto