Lube and seal oil systems, and steam and process gas piping require a thorough cleaning before a new machinery train can be commissioned. Cleaning seal and lube oil systems is also often required during a machinery turnaround. In practice, however, cleaning these systems rarely gets the attention deserved. The reasons are multiple; following are some typical stories:

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The process department claims that the process gas piping is already clean because it was flushed. Translation: “Someone dumped the water after the hydrostatic test!”
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Blowing steam lines is left to the process personnel without any practical engineering guidance. As a result, the lines are blown for long periods or until the noise cannot be tolerated any longer. Targets are not installed, flow rates are inadequate, and flow meter orifices left in the line are damaged; yet no one is certain that the lines are really free of damaging debris.
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Cleaning lube and seal oil lines proceeds for days, but the gauze pads still remain full of metallic particles. Shortcuts are then taken when the project schedule is jeopardized.
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Small but crucial lines are forgotten. Buffer gas supply lines and balance lines are often ignored. Yet these lines feed gas that must flow through restricted passages or through labyrinth seals. Small metal shavings or weld slag left over from piping fabrication can cause considerable damage when caught between rotating and stationary parts.