PTFE coating repair for existing pressure vessel

[eiadro1]

hello
im having a case right now of an existing vessel which is PTFE/PFA internally coated - we are going to do some vessel alteration and modification of the vessel by adding some nozzles . accordingly the exiting PTFE coating will be removed before welding and shall be applied again before bringing the vessel in operation again .
my questions :
can we do repair work of PTFE curing temp at 400 c on site ?
and if so such temperature can damage the rest of PTFE coating due to heat effect ?
how is the right methodology to get the PTFE repair done ?

 

[eiadro1]

any experience pleeez

 

[snoopnoon]

My experience may not be much help. But on one of our installed steam turbine oil tanks that was being retrofitted with filters, the concern was the coating on the inside of the tank after welding the new inlet/outlet pipes. Ultimately it was a choice between doing the entire tank over (not an easy task) or doing local repairs for which the material is expensive but is not guaranteed to last.

We expect there will be issues with the coating at some point, but for this project the choice was cycle over doing it right.

 

[LittleInch]

Might have been better posted in the boiler and pressure vessel forum, but my experience with coatings like this is that they are so specific that you need to seriously discuss the options with the vendor and applicator to see what your options are. You will probably need to do a test piece to demonstrate that the essentially repair technique is qualified for your use.

first point of call would be to look at the original application and what they would use for a coating repair of the original PTFE lining.

Repairs and discontinuities are usually an ongoing weak point. Only you can judge if failure of the coating could be identified or could be catastrophic. You might need a different coating or material for this new nozzle and up to the original coating.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[eiadro1]

thanks for your reply
i already discussed with several vendors and all of them assured that PTFE cant be cured at site due to curing temperature so we tried to convince client and now we are searching for alternative coating that gives the same surface finish but durability may not be same as normal PTEF .

 

[snoopnoon]

your next best bet is probably POR-15 or similar, but not a permanent solution.