A Case History of a Large FRP Tank Fabricated in a TIGHT Place

A primary neutralization tank made of FRP was 30 years old and leaking from somewhere at the bottom. The vessel was open top with an 18' diameter and 20.5' straight shell. The vessel was surrounded by a metal structure, which supports the vessel's agitator, as well as, housing covering valves and equipment used for the primary and secondary neutralization vessels. The vessel had to be replaced, but since the vessel was the first one to neutralize the waste stream, it could not be out of service for too long. The cost of removing the metal structure and replacing it would be very costly and require additional time.  The question was how could the vessel be replaced without removing the metal structure?

Large FRP vessels have been fabricated in separate sections at fabricator shops, and sent to assembly sites for several decades.  Fabricator personnel cut the existing tank in pieces and removed the pieces with the metal support structure in place. The new vessel was received in five pieces: the bottom and top section in two half moons each, and the center section in one piece. The new vessel's parts were moved into place and assembled.  This paper describes the methods used to remove the old vessel and install and assemble the new vessel.