Seeking advice on pressure testing floating-head heat exchangers
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During the major overhaul of the equipment, the floating-head heat exchanger is an old unit; the operating pressure on the shell side is 3 MPa, while the circulating water pressure on the tube side is 0.4 MPa. When performing leak testing after cleaning, can 6 kg of nitrogen be used for this purpose, or is it necessary to use the pressure specified in the drawings for the hydrostatic test?
This post was last edited by CHANGBAISHI on 2020-2-29 07:56. For high-capacity pressure vessels, a hydrostatic test remains the safest option. “It is mandatory to use the hydrostatic test pressure indicated on the drawings – this requirement must be followed. Water has low compressibility, while air has extremely high compressibility. Once problems occur, resulting in roaring noises and shockwaves...... the consequences are unimaginable.
In my opinion, since gases are highly compressible, a small leak does not result in a significant drop in pressure. In terms of safety, water is much better than nitrogen; definitely, water is the better choice.
During the maintenance of heat exchangers, pressure testing is preferably carried out using a hydrostatic test, with the pressure applied being 1.5 times the normal operating pressure. Under normal circumstances, testing should not be conducted at the pressure specified at the time of manufacture; the use of pneumatic pressure is not recommended, and if it must be used, a safety valve must be installed. Pneumatic testing is quite dangerous
You can check the maintenance specifications; there are requirements listed there.