Corrosion in cold water pipes

Dionne, Jean-François
5/30/2023 9:33 AM

Cooling water systems are very common in large buildings or industry. Some niche applications might require very clean water but it’s also very common to use tap water for less critical applications.

Even with special chemicals, corrosion can still appear in piping systems made of plain steel. Corrosion might not be a serious problem, at least for larger pipes, if it is limited to a small uniform thickness. This corrosion layer will help to slow down the progression of corrosion and “protect” the pipe.

One client recently installed a new piping system in an important building in Geneva. After only 6 months in operation, the new pipes were starting to show several perforating leaks along the longitudinal welds.

Investigative analyses showed the weld’s thickness in the vicinity of the problematic segments was reduced to just a few millimetres. Corrosion was expected to occur but the weld thickness was not sufficient to account for it, hence the pipes started to leak.

Incremental cross-sections along the weld line showed perturbances in the weld line. This problem can come from an improperly prepared edge, or an edge defect on the original steel sheet that was bent into a pipe. It could also come from a disturbance of the automatic welding equipment but this is however less likely since it would have more negative effects in the pipe production line.

#corrosion #root-cause #asset #integrity