Original Date: 08/26/1996
Revision Date: 01/18/2007
Best Practice : Vessel Replacement Specification Development
WSC began using the basic oxygen steelmaking process in Fall 1967. Two furnace vessels, used on an alternate, rotating basis, allow necessary routine maintenance and refractory reline work to occur on the idle vessel without disrupting daily operations. At 365 tons, these vessels have the largest capacity of this type in North America. Since becoming operational, one vessel has been replaced twice, in 1975 and 1986. The other vessel was repaired in 1988 to correct distortion between the trunnion ring and the body shell. This repair extended the vessel’s useful life for another three to five years, and allowed WSC the time to develop a replacement vessel specification, arrange for the necessary funding, and assemble a new vessel. Lead time for fabricating a new vessel was 26 months with an additional 10 months for field assembly and changeout of the old vessel. This factor required that a specification be developed and funded, so a new vessel could be purchased in time to support the extended end-life of the repaired vessel.
To develop the specification for the new vessel, WSC assembled a team to establish the requirements and ensure that input was provided by all responsible personnel who would be involved in the project. The team reviewed and evaluated the existing specifications from the previous purchases and recommended changes. They benchmarked with other steel producers and received technical input from recognized experts in the field of vessel design as well as vessel fabricators. The completed specification required that the new vessel be designed and built to last at least 25 years to offset the high cost of replacement. It had to be dimensionally identical to the other vessel in use, and be able to accept the reuse of existing components and spare parts. The design had to be such that it could be assembled on-site with minimal fitting and welding by WSC personnel.
The appropriation request for the new vessel was approved in 1989 for $5.5 million with an understanding that the funds for the assembly and installation of the vessel would be requested at a future date to coincide with the extended end life of the repaired vessel.
Four companies bid on the proposal for the fabrication of the new vessel. The selection and award was made in the third quarter of 1989. Fabrication time was estimated at 17 months with an additional 10 days of inspections required at the builder’s site by WSC personnel. The vessel was completed and delivered in May 1991, on schedule and at approximately $500 thousand below the estimated cost.
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