When to Pickle/Passivate a heat exchanger?
When to Pickle/Passivate a heat exchanger?
(OP)
Hello, I have a new reboiler that will be going into service in a few months. The tube side is AL6XN and is in oil service (pH=5), the shell side is 316L and is in Dowtherm A service.
I have heard of pickling exchangers before, but do not know when it should be applied.
Are there some guidelines to determine when this is necessary?
Thank you,
I have heard of pickling exchangers before, but do not know when it should be applied.
Are there some guidelines to determine when this is necessary?
Thank you,





RE: When to Pickle/Passivate a heat exchanger?
Passivation timing depends on whether or not you are passivating any of your piping also.
Do it late as possible.
If there is localized discoloration from welding this can be cleaned using a pickling paste.
I would hope though that this was built with good enough shielding during welding that this would not be needed.
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P.E. Metallurgy, Plymouth Tube
RE: When to Pickle/Passivate a heat exchanger?
Thanks again,
RE: When to Pickle/Passivate a heat exchanger?
If the system is mixed metallurgy including steel then there isn't much point as things will get rust covered anyway.
I would inspect the welds carefully to assure that there is no heat tint, and that they were not mechanically ground.
If you find either case I would recommend pickling paste.
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P.E. Metallurgy, Plymouth Tube