Repair or maintenance of a shell and tube heat exchangers can be an unsafe procedure. It needs to be separated, taken offline, and moved to shore for repair. Shell and tube heat exchangers are made of curled tubes and can get to be fouled with carbon filings. The traditional systems for clearing the blockage incorporate bypassing the fouled unit, cutting off twists and cleaning the tubes, then re-welding the U-bends, and whole unit replacement.
