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In recent days we have found that in our refinery the bottom/lowest course of the crude tank is severely corroded, especially the lowest one metre. We intend to replace the bottom course without replacing other courses. the course height is 1829 mm. the diameter of the tank is 69 m. the thickness of the bottom course is 20.0 mm and the immediate above course thickness is 17.0 mm. The height of the tank is 12 m. We will also replace the annular plate and bottom plate. Can anyone help me which will be the right procedure to replace the course?
 
Answers
24/08/2009 A: keith bowers, B and B Consulting, kebowers47@gmail.com
Hire a real good tank builder (CBI, etc) and have them design the repair plan for you. Then seek bids from qualified tank repair firms. DO NOT attempt to do it yourself. There are MANY detail and particular tank specific factors that must be evaluated and incorporated in the plan, and revised accordingly after the tank is cleaned and again inspected prior to beginning the work. Workmanship of every person working on the tank is critical, as is a good design/plan of work. Materials--plate, filler rod, shape of plate edges, backing strips, foundation, bedding/membranes,etc.NOT a trivial undertaking.
The ring has to be replaced in sections of course, as does the bottom. The overall plan seems simple. but, oh, the details.
24/08/2009 A: Mike Watson, Tube Tech International Ltd, mike.watson@tubetech.com
We have:
a) Welded a 20mm x 1m x circumferential skin around the outside of the 20m dia. tank, then with man entry, cold cut the inside corroded course.
b) Cut sections at a time and rewelded in new segments. Typically 3m x 1m x 20mm strips.