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After over three miles of high-density polymer pipeline was installed with over 800 couplings, the initial 25 PSI hydro testing resulted in 50-60 percent of the couplings leaking. The couplings leaked because gaskets were damaged during installation and because the pipe sealing surfaces were improperly prepared. Gasket damage was caused by gasket misalignment because of improper lubrication being used to install the gaskets, among other problems. This problem resulted in a $525,000 profit reduction due to delaying startup by two weeks ($400,000) and increasing out-of-pocket costs by $125,000 for repairs. Our customer was also unhappy with the delays. Additional, potential impacts include reportable spills due to the leaks, possible loss of a $5M contract and $100,000 in clean up costs. Solutions include, but are not limited to, using a vegetable oil for gasket lubrication during installation; polishing the sealing areas of the pipe prior to installing gaskets; using a Sawzall with a fine tooth blade to cut pipe instead of a chainsaw; shading the installation surfaces on sunny, hot days; and incorporating the piping and coupling manufacturer's recommendations into the piping specifications.
Cause and Effect Summary
The multiple piping leaks in the piping was caused by multiple leaks at the couplings. The couplings leaked because gaskets were pinched/damaged during installation and because the pipe sealing surfaces were improperly prepared. The pinched gaskets were caused by the gaskets not sliding into designated seating areas within the coupling. The gaskets did not slide adequately due to lack of lubrication which would have allowed the gaskets to seat properly when the coupling was tightened. The lubrication used during installation was a soapy water solution with an unknown ratio mix of water and soap. The ratio of soap and water is unknown because the installers did not track the amount of soap put in the water bottles, but it was stated that there was not much soap in the mixture. A soapy solution was recommended by the manufacturer, but considering this application in the hot, sunny desert climate, it was ineffective because the water evaporated too quickly.
Aside from the gasket pinch, additional causes related to imperfections in the pipe surface area did not allow gaskets to form a seal. These imperfections include scratches, gouges, and abnormalities in the pipe’s gasket surface area. Scratches were created mostly during pipe transfer from the storage/staging area to the installation area. The scratches came when the 50 foot pipe’s ends dragged on the ground during transportation. The pipe is lifted from the center with a forklift, but the high-density polymer pipe is malleable (especially when heated from warm ambient temperature) and the flexibility of the pipe allows the ends to bend and touch the ground. While not in constant contact with the ground, the transportation path is not smooth, level, and flat so the ends come in contact with ground surface and rocks when moving into installation position.
Most of the smaller imperfections were not addressed during the original installation (only the dramatic gouges were prepped or eliminated). The seemingly smaller surface area scratches and imperfections were not highlighted as an area of trouble during the onsite coupling training provided by the manufacturer, so installation technicians were not aware of which surface imperfections required attention and which imperfections were acceptable. The demonstration that the manufacturer's representatives provided during training included installation of a 3” coupling on 3” PVC pipe with no lubrication. Scratches, lubrication, and high-density polymer pipe were not addressed during this demonstration; however, it is noted that when asked if soapy water could provide sufficient lubrication for installation, the manufacturer's representatives confirmed that a soapy solution would be acceptable.
It is important to note that the manufacturer was not part of this investigation, and evidence gathered is from the installer’s statements, photos, and supporting documentation. The manufacturer did provide field installation handbooks with additional installation instructions and recommendations, but these handbooks were not used during installation, as field personnel assumed the onsite training was sufficient enough to install the couplings.
Other surface area imperfections were created from chainsaw cuts used to adjust the pipe length in between couplings. Occasionally, the 50-foot standard pipe length was not appropriate when navigating the plant area, so the pipe would have to be cut shorter for specific applications. These cuts are not factory cuts and thus introduce a surface area that may contain imperfections such as uneven cuts (out of square), chain marks on the end of the pipe, and excess material left from rough cuts.
Lastly, the leaks were not detected until the pipeline construction was completed because no incremental hydro testing was performed during construction. Originally, the project manager assigned to this project had to leave shortly after bidding and project kick-off. Once construction began, a new highly-recommended project manager was assigned. While incremental pipe testing was discussed between the original project manager and the internal project engineer, the new project manager was not aware of the need and did not perform incremental testing. It is unknown why the new project manager did not perform in-construction hydro testing. The new project manager was unavailable for this investigation as he is no longer on this project.