Repairing dents in an underground carbon-steel pipeline

Dents in transmission pipelines are a common problem that need to be fixed as soon as possible. Dents will make the pipeline in that particular area weaker. There is a chance of crack forming or even creation of a hole if the dents are not properly repaired. CTE BV is working with epoxy composites and carbon fiber cloth to save repair the pipeline. Compressive Modular Filler (CMF) is applied to bring back the dent area in it’s normal shape. The carbon fiber cloth in combination with epoxy composites will bring back the integrity of the pipe after curing. The case study explains how to approach a dent defect in your pipeline. The repair is performed according the standard ISO 24817.

Challenge

The repair has to take place under pressure to push out the dent as much as possible before applying the CMF putty and carbon fiber wrap. Often natural gas pipelines are buried and access is only allowed when the installer did receive a confined space training.

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Repairing a carbon-steel pipeline 11 meters above the ground

Repairing a tee using composites needs a special training program. During Level-1 training courses applied by CTE BV applicants will be trained according ISO 24817 and/or ASME PCC-2 standards. If applied correctly the number of layers over the defected area should count 4-8 layers. In this case one of the girth welds needed to be strengthen by applying a carbon fiber and epoxy composite repair. This operation is a very common activity that trained installers perform daily.

Challenge

The particular challenge in this case was working at height and with a High Temperature solution. Access to the repair area was complicated due to the lack of being able to bring in aerial platform equipment. Scaffolding was the only possibility for the installers to save repair the tee. Although the cost for scaffolding and other safety precautions did increase operational costs, the composite repair was preferred above replacing this part of the pipe. Finally the high ROI (Return on Investment) did decide management to carry out the repair.

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