Sun. Jun 20th, 2021

City gas distribution

Transporting future fuel

#97 Dents in pipeline

2 min read

All dents that affect the curvature of the pipeline at the longitudinal
weld or circumferential weld shall be removed. The depth of dent shall be measured as the gap between the lowest point of the dent and the original contour of the pipe.

The maximum permissible depth of dents in pipes up to and including 12.75” inch (324 mm) nominal outside diameter shall be 5 mm. For pipes over 12.75” inch (324 mm) nominal outside diameter, the permissible depth of dent shall be 2 percent of the nominal pipe diameter. Length of the dent in any direction shall not be more than one-fourth of nominal diameter of the pipe.

Dents shall be removed by cutting out the damaged portion of the pipe as cylinder and replacing with a pre tested pipe.

All dents as mentioned in above para and a dent containing a stress concentrator, such as a scratch, gouge, groove, or arc burn, shall be removed by cutting out the damaged portion of the pipeline as a cylinder and replacing with a pre tested pipe section. Buckled pipe shall also be replaced as a cylinder.

Notches or laminations on pipe ends shall not be repaired. The damage portion shall be removed as a cylinder and re-beveled to the pipe properly.

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