C - Chemistry – Metallurgy – 21 – D
Patent
C - Chemistry, Metallurgy
21
D
285/44, 148/34.6
C21D 9/08 (2006.01) B23K 9/028 (2006.01) C21D 9/50 (2006.01) F16L 13/02 (2006.01)
Patent
CA 1324062
"PIPE LINE WELDING IMPROVEMENT" ABSTRACT OF THE DISCLOSURE A process is provided for heat treating an annular martensitic heat-affected zone. The heat-affected zone is commonly created in the outer segment of a pipeline wall as a result of applying a circumferential fillet weld to the pipe. The embrittled zone creates a weakness in the pipe wall and it is therefore desirable to heat treat it. The heat- treating process is carried out in connection with a situation where the pipeline has an open end located close to the weld and a plug has been inserted in the bore of the line to isolate the main part of the line from the pipe end having the weld. An expandable and contractable insulating ring is inserted into the pipe bore. The ring is associated with a closure member which blanks and seals the open end of the pipe. The isolating plug is removed and the ring is positioned beneath the weld and expanded to abut the pipe wall. A final circumferential weld or bead is then applied to the existing weld, which causes heating of the martensitic zone. The insulating ring is maintained in place against the pipe wall to ensure that the heated zone cools only slowly. This results in reduction of the hardness of the heat- affected zone. The isolating plug is then re-inserted and the insulating ring and closure member are removed.
570884
Interprovincial Pipe Line Inc.
Johnson Ernest Peter
Savard Donald D.
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