Q: We have a problem with rust in a plant.  Our downstream filters keep filling up with rust particles. Please see the attached picture. What do you think has gone wrong?

A: I suspect that part of the steel piping in the plant is getting wet, likely from compressor overheating during hot days, or dryer failure due to overload (also caused by excessive heat).  During cooler temperatures, the piping becomes dry due to normal conditions.

If fed by lubricant free compressors (these often have acid condensate), or if lubricated compressors are pulling in various chemicals from the ambient air, the condensate inside the pipes might be acidic, which will increase the rate of rust corrosion in steel pipes.  When normal conditions occur, and the pipe becomes dry, the rust flakes off, and is passed downstream into the end use filters.

Possible solutions include:

• Ensure dryers are working in all conditions
• Solve any overheating problems
• Change any pipes and receivers to coated type or material that does not rust
• Install main particulate filter, and maintain it on an accelerated schedule

Depending on the condition of the piping internals, it may be quite a while before the rust problem is solved.  Maintain the filters well.