Storage tanks and pressure vessels play an integral role to all piping systems.  Due to their different designs, a wide range of corrosion related concerns exist.  Above all, any tank or pressure vessel having a varying water line, such as for domestic water storage or an expansion tank, will experience noticeably higher corrosion and pitting between its high and low water levels.  The failure of any pipe leading to or from a tank or pressure vessel should always prompt a concern for its condition.

Pressurized vessels are at a far greater threat than for unpressurized tanks, with examples such as deadly explosions at compressed air storage tanks all too frequent.  As always, the much older water storage and pressurized fire sprinkler tanks were constructed of heavy 1/2 in. steel plate.  Yet today, that wall thickness has been substantially reduced.  Any old water storage tank installed prior to 1940 has likely been internally coated with red lead paint and/or coal tar for corrosion protection – both major health issues requiring abatement.

While most ultrasonic investigations relate to water storage due to the potential for large scale damage and service interruption, ultrasonic testing is also appropriate in defining the condition of tube and shell heat exchangers, steam surface condensers, make-up water deaerators, steam condensate tanks, centrifugal separators, air separators, and refrigeration chiller shells.

This series of Photo Galleries provides examples to the vulnerability that virtually all water storage tanks have to corrosion, whether internal or external.