Is coating/ lubricating heat exchanger internal bolts advisable?

[srijey]

Under what conditions Shell and Tube heat exchanger internal bolts found in floating head flange, baffle plates, tie rods need not be lubricated or coated? I understand the process fluid generally washes out the coatings on the fasteners. In that case, the available clamp force on the fasteners would change while in service. Is it a practice to identify the compatibility compound or coating for fasteners for that service and operating conditions? TEMA and API are silent on such matters.

 

[muld0020]

I would follow TEMA RCB 5-13, which is very generic but correct. You need to use good judgment. I'm not sure I understand your question completely since coating and lubricants can mean a lot of different things to different people. Maybe some more detail in your question would help.

 

[srijey]

Thank you Muld. I meant only anti-seize compounds which influence nut factor. In addition to process fluid contamination, this lubricant, in most cases, will be carried away by the fluid stream. That is the chief argument against the use of lubricant on internal fasteners. I was looking for a standard practice or guidelines in order to avoid that 'subjective' engineering judgement!

 

[jtseng123]

you already have the answer, that is the common practice and don't need any guidelines. No one will ask this question, at least I never heard of for hundreds of pressure vessels and heat exchangers through my hands.

 

[srijey]

I've come across certain investigations pointing out the loss of anti-seize compounds in internal fasteners on bolt relaxation issue. Another issue was the contamination of clean service fluid. Now that you've confirmed that this is purely operating companies' requirements, I'll not attempt to standardize a practice in our territory.