Reusing a 20 Years old exchanger

[Nabeel Ahmed Qureshi]

One of the exchanger at our site was taken out of service back in 1991. Now we are relocating that exchanger to reuse it at some other place. Does this exchanger needs re-rating or the De-rating factor applies?

Design Pressure - 455psig (shell) & 885 (Tubes)
Design Temperature - 690 F (shell) & 445F (Tubes)
What checks shall be done before we declare this exchanger fit for use.

[ben]

What's the type of heat exchanger?

I have mentioned some of the check you can perform.
1. First of all you must take thickness readings of the accessible areas. See where the thickness is standing on shell and tube side (assuming shell and tube heat exchanger). Corrosion allowance has been eaten up or things have gone more bad.
2. What's the material of tube? Perform eddy current checks if possible.
3. See past history records / inspection reports, if any, for chronic problems.
4. Perform visual check of all the tube-to-tubesheet weld joints.
5. Closely observe the gasket sealing area of both end flanges.
6. If you find thickness lower than design, share the thickness data with design engineer who would be performing maximum allowable pressure / temperature checks to re-rate this exchanger. Only after his evaluation, perform a hydrostatic testing against re-rated hydrostatic test pressure.
7. If thicknesses are looking good, perform hydrostatic testing to find any leakages.

[Nabeel Ahmed Qureshi]

Thanx ben. Really a great help. Pls find below the answers o your questions.
The exchanger is a Floating head fixed tube sheet type.
Tube material is A-210 A-1.