S9074-AR-GIB-010/278
6.) The Post weld thermal stress relief requirement of the ASME Code, section I and VIII, as applicable, may be used provided the holding temperature ranges specified in this table are used. The table selected shall be used in its entirely, exclusive of the others. 7.) Stress relief is not required for the following welds in 2-1/4 Cr-1 Mo and 1-1/4 Cr-1/2 Mo boiler superheaters when welded in accordance with NAVSEA 0951-LP-031-8010 or NAVSEA 0951-LP- 038-6030, as applicable, using low carbon ( 0.05 maximum carbon content ) filler material.
(a) External superheater tube-to-header welds of NAVSEA 0951-LP-038-6030 figure 7-2 and repairs to these welds which are not deeper than maximum design weld joint depth.
(b) Internal superheater tube-to-header "seal" welds which have a maximum groove depth, before welding, of 1/4 inch or less, where tubes are fully rolled into the header prior to welding. For the purpose of this requirement, groove depth shall be determined at the location of minimum counterbore depth.
(c) Weld repairs to internal superheater tube-to-header "seal" welds which extend no deeper below the header inside surface than "b" above.
(d) Tube plug seal welds of 1/4-inch maximum throat thickness.
(e) Handhole plate seal welds of 5/16-inch maximum throat thickness where handhole plates are entirely secured by an integral threaded system.
Omission of stress relief for any other welds (that is, internal tube-to-header "seal" welds of greater than 1/4-inch groove depth, tube hole repairs, minor header repairs, and so forth) shall require specific approval by NAVSEA. 8.) Part must be cooled to ambient temperature before final heat treatment. Minimum hold time at temperature shall be 2 hours. Above 2 inch thickness add 1 hour for each additional inch, or fraction, of thickness. A double temper heat treat cycle with 1250 + 25*F for the first temper is permissible. The final temper shall be 1125 + 25*F. Minimum hold time for each temper shall be 2 hours plus 1 hour for each inch, or fraction, of thickness over 2 inches. 9.) This holding temperature shall be used for 410 or 410S steel welded with 410N1Mo weld metal. Part must be cooled to ambient temperature before final heat treatment. Minimum hold time at temperature is 4 hours. Above 4 inches add 1 hour for each additional inch, or fraction, of thickness. Separate welding procedure qualification using these temperatures is required; HAZ toughness testing shall be performed. 10.) An alternate double temper heat treat cycle for 410 or 410S steel welded with 410N1Mo weld metal. Part must be cooled to ambient temperature before 1st and 2nd parts of heat treat cycle. Minimum time at temperature for each part of heat treat cycle is 2 hours. Above 2 inches add 1 hour for each additional inch, or fraction, of thickness. Separate welding procedure qualification using these temperatures is required.
Original 68
Made with FlippingBook - Share PDF online