Importance

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Abstract

To connect cylindrical members, e.g., pipes to each other by welding, a tandem type internal clamp composed of two or more clamps is used as an essential component. Prior to each welding operation, the tandem type internal clamp is located in position in a pipe to be newly connected to a pipe already connected to a preceding pipe. At this time, one of the clamps corresponding to a circular welding seam is slightly projected outside of one end of the new pipe. As expansion ring segments are radially displaced in the outward direction, seal ring segments are brought in close contact with the inner peripheral surface of the new pipe. Subsequently, the new pipe is displaced toward the already connected pipe until the tapered welding edges of both the pipes abut against each other, causing the projected part of the clamp to be inserted into the already connected pipe. After positional offset of the new pipe relative to the already connected pipe is eliminated if any, inert gas is fed into the hollow space defined between the seal ring segments of each of the clamps so as to start a welding operation to be performed around the tapered welding edges of both the pipes.

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First Claim