The authoritative public forum
  for Metal Finishing since 1989
-----

Phosphate bath and steam coil build-up

I am a currently work for a midwest manufacturing company. We are experiencing extreme amounts of build-up on our Stanless Steal 2" Steam coils in our phosphate baths. This is causing nozzels to plug and have to be replaced weekly. Secondly, the coils are only lasting 2 to 3 weeks before we have to take them out and beat off the build-up with a hammer or acid clean.

Looking for knowledge of how to improve the efficiency of my system so that we can reduce the loss of heat going to the tanks and scrap parts.

Is there filtration units out there for removing phosphage sludge so that it does not adhere to the steam coils?

Is there an additional corrosion inhibitor that can be used in the tank to keep the phosphate from adhereing to the steam coils?

Brian Euclid
employee - Columbus, Ohio, United States
February 8, 2008

---

letter 11465 is a good start on this, or patiently search the site, Brian. This one keeps coming up. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
February 11, 2008

---

Mr. Mooney,

you mentioned paint that can be used, is there a specific brand name or company that specializes in this?

Thanks,

Brian

Brian Euclide
- Columbus, Ohio
March 3, 2008

---

I read about the paint so long ago that unfortunately I have little memory of it. Hopefully a reader who is familiar with it will reply.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
March 4, 2008

---

The reason that you have a buildup on the coil is because it is so hot. Try lowering your steam pressure and thus the temperature (at least after the initial solution warm up). You can send the coil out and have a teflon coat (paint) put on it which can stand the temperature and the solution at the cost of a bit less heat transfer rate. Note that as it ages it will still build up the coating because of the high temperature of the coil. Increasing the agitation (solution flow) across the coil will help to hold the temp down some.

James Watts
- Navarre, Florida
March 4, 2008