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HI TEMPERATURE ANTI-GALLING COATING

I AM LOOKING FOR AN ANTI GALLING COATING TO USE ON 1" AUTOCLAVE TYPE PIPE COUPLINGS THAT WILL CYCLE BETWEEN 50 AND 650 °C. THE THREADED STAINLESS STEEL AND INCONEL 625 PARTS ARE DISASSEMBLED/REASSEMBLED IN THE FIELD ON A REGULAR BASIS FOR REBUILDING AND CLEANING. CAN YOU SUGGEST A COATING OR PLATING THAT WE CAN HAVE APPLIED TO PREVENT THIS FROM HAPPENING? THREADED COMBINATIONS ARE :
INCONEL TO INCONEL
INCONEL TO STAINLESS STEEL
CARBON STEEL TO STAINLESS STEEL
CARBON STEEL TO INCONEL
CARBON STEEL TO CARBON STEEL

JOHN AUGUST LOMBERK
CITY OF ORLANDO - ORLANDO, FLORIDA, USA
2007

Teflon tape sounds like the best bet. It is also cheap and renewable as required. I would not use anti-seize or pipe dope.

James Watts
- Navarre, Florida
2007

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2007

Electroless nickel boron iaw AMS2433 type II or Enkl/PTFE iaw AMS2404 would likely solve your galling problem.

Patti Kientz
plater - Santa Ana, California, USA

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I would be concerned about cycling between 50 and 650C, as PTFE will not survive these temperatures. I am also dubious about the using electroless nickel at these temperatures as there could be a risk of embrittlement, but perhaps someone with more experience of electroless nickel can shed some light on that. Personally, I would suggest giving the parts an electrolytic coating of silver. Use a cyanide silver strike to get good adhesion and it should overcome your galling problems. Silver is a pretty efficient depositor, so there shouldn't be too much risk of hydrogen embrittlement either.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2007

Use Brush Plating or Selective Plating. We use it daily for our production.

Sunny Tan
- Singapore
February 11, 2010

Shall be thankful to know which of the various suggested answers you adopted and what was your experience

Ranadev Chatterjee
- Khobar, Saudiarbia
April 10, 2011