The Illinois Power Company was spending too much time and money removing and reinstalling torus rings on high pressure feedwater heaters, due to quality and productivity problems. Previously, torus rings were removed by flame cutting (oxy-acetylene) by hand with the assistance of a fixture. The resulting kerf was often very rough and not in the same plane. To make the joint acceptable for rewelding, a considerable amount of time was spent grinding, building up low areas by welding, and then re-grinding. If the torus ring was not severed in the same plane, fit-up problems had to be overcome upon reinstallation. Once the torus ring was removed from the feedwater heater, the welding procedure required a 45 degree bevel be reestablished on the torus ring. The bevel was also produced by manual flame cutting, which resulted in the same problems described above. The torus rings were often ruined upon removal, or their service life was substantially reduced. With replacement torus ring costs approaching $6000 each, the company hoped they could save money by increasing service life. To remove and prepare each ring required 36-40 hours.

Torus ring removal by machining was too time consuming to be a viable option. Flame cutting with automatic equipment and a swivel cutting tip (to overcome clearance problems) was the solution determined to yield the greatest economy of time, money and quality. The BUG-O Systems HOB-O was chosen to do the job.

The results that were produced achieved smooth kerf and bevels, requiring minimal grinding. The service life of the torus rings was at least doubled. The fit-up on reinstallation was excellent. Compliance with the welding procedure specification requirement was simplified and the man hours involved were reduced from as much as 66 to 75%.

Equipment: BUG-O Systems DC HOB-O, 2-hose machine torch, adjustable tip adapter.

BUG-O BOWL ENTRY 95-21
Submitted by David P. Weber
Illinois Power Company
Baldwin, Illinois