Specification for the Reattachment of the EC South Cryostat Heads

Abstract

This Engineering Note defines technical requirements and the scope of work for reattachment of the heads of the South EC cryostat. This work is to be done in the clean room at the D-Zero Assembly Building (DAB) at Fermilab.and is expected to begin around September 15, 1991. The task consists primarily of welding four heads onto a 17-foot diameter stainless steel double-wall pressure/vacuum vessel. Nominal thicknesses of the welds are all 5/8-inch. Root passes are to be made by TIG welding and the balance by MIG welding. No radiography is required; other NDE per ASME Code, Section VIII, Div. 1. All work is to be done in accordance with the Rules of the National Board of Boiler and Pressure Vessel Inspectors (ANSI/NB-23), and repairs to the inner vessel are to be documented by the R-1 form executed by the Contractor's Authorized Inspector. The Contractor will be expected to work two shifts per day, five days per week to support the Fermilab schedule. Details of the cryostat are given on Fermilab Drawings 3740.220-ME-222256, Rev. R, 3740.224-ME-273071, and 3740.224-ME-273039. The cryostat was fabricated by Process Engineering, Inc. of Plaistow, NH in 1989-90. The heads were removed using hand-held air-arc gouging equipment. As a result the welding grooves are not straight and their widths are not uniform. In some places the width maybe as wide as 1-inch. For the purposes of quotation, the Contractor should assume a uniform weld groove as shown in Figure 1. The amount of weld metal to be deposited for this geometry is estimated to be 500 lbs. Upon completion, the final contract price will be determined by the following formula: Final Price = Contract Price x (lbs of weld metal deposited/500). Methods of determining the amount of weld metal deposited will be agreed upon before award of the contract.