MIC on Potable Water Piping.

Contractor has just completed the installion of 6" 304L ss potable water piping. After 3 months, 50% of the 300 welding joints has been observed leaking . Pitting attack has so far been confined only at the weld joints.. No failure was observed in the process ss lines.

Expert from Nalco has been called to assist and identify the cause of pitting and weld failure. Nalco says the cause is MIC. No it does not stand for microphone but rather to microbiologically influenced corrosion caused by anaerobic acid producing bacteria.

System has been treated with shock dosage of chlorine, but what do you know. Damn MIC can survive in chlorinated water. Its source unknown.

What suprises us is how come this bugger only loves to eat a weld joint ? Our lab has also indincated that this bacteria is no health hazard - system is potable water. Meaning its ok to drink the wtaer because the MIC only attacks a ss weld joint (the bugger must have hated a human intestine)?

Anybody has any experience on this MIC?

Metallurgist suggestion is top apply a leeve around the weld joint using AL-6XN or wrap with fiberglass or compeltely replaced it with galvainzed cs pipe. Received on Tue May 29 07:02:00 2001