Sandblasting flange and piping side affected paint on flange nuts and bolts
Sandblasting flange and piping side affected paint on flange nuts and bolts
(OP)
The paint on hex nuts and bolts was affected by sandblastng operation done on flange joint piping. No mechanical damage was noticed on the body, face or thread of nuts and bolts. The bolts are torqued and the line is in service. My question is do we need to replace the affected bolts or just re-paint will be sufficient? See attached picture.





RE: Sandblasting flange and piping side affected paint on flange nuts and bolts
RE: Sandblasting flange and piping side affected paint on flange nuts and bolts
RE: Sandblasting flange and piping side affected paint on flange nuts and bolts
But! You MUST immediately coat them to prevent the "clean metal" from rusting away because their primary rust protection is gone. Expect to replace the bolts next outage because thread damage while unscrewing them is almost certain to occur on more than 1/2 of the bolts.
RE: Sandblasting flange and piping side affected paint on flange nuts and bolts
The fastener is an A193 Grade B7 Chromium-Molybdenum Alloy Steel stud bolt chosen for its corrosion resistance and high-temperature strength.
The Fluoropolymer coating (bluing), topcoat is intended to reduce friction during tightening.