PROPOSAL PAGE 1 OF 5 Case 2697 Unstayed Flat Head Constructed From Forged Material Section I Inquiry: Is it permissible in Section I construction to utilize flat heads with integral flanges constructed from forged material? Reply: It is the opinion of the Committee that it is permissible to utilize flat heads with integral flanges constructed from forged material as depicted in Figure 1. Flats heads of NPS 4 (DN 100) and smaller shall be constructed in accordance with SA-105, SA-181, SA-182, SA-234, SB-366, SB-462, or SA-815 (UNS S31803 only). Flat heads larger than NPS 4 (DN 100) shall meet the following requirements: (a) The flange may be formed by machining a forged blank or it may be formed by direct forging action. (b) The flat head (1) The flat head shall comply with PG-31. (2) C = 0.33m but not less than 0.20 (3) The flat head thickness shall not be less than the shell thickness. (4) The corner radius (Figure 1) on the inside is not less than the following: r = 0.375 in. (10 mm) for t s 1½ in. (38 mm) r = 0.25 t s for t s > 1½ in. (38 mm) but need not be greater than ¾ in. (19 mm) (c) The welding shall meet the requirements for circumferential joints given in Part PW. (d) The center of the butt weld to the shell shall be located at a distance, a, not less than the nominal thickness of the flat head, as measured from the center of the inside corner radius. (e) The forged stock shall have a forging reduction ratio not less than 2:1 in the direction radial to the plane of the blank disk and an upset reduction not less than 2:1 in the direction normal to the plane of the blank disk. The forging reduction ratio shall be calculated by dividing the cross-sectional area prior to forging by the crosssectional area after forging. For upset forging the inverse atio shall be taken. The forging ratios in each plane may be calculated as the arithmetic sum of the ratios of more than one forging operation in that plane. The forging operations may be undertaken in any order. (f) Tension Test Specimen (1) The flange shall have the minimum tensile strength and elongation specified for the material, measured in the direction parallel to the axis of the vessel. Proof of this shall be furnished by a tension test specimen (subsize, if necessary) taken in this direction. (2) For heads machined from a forged blank, the tensile specimen shall be taken from material on the inside of and adjacent to the flange. The finished surfaces of the specimen that face the finished surfaces of the head shall not be more than ¼ in. (6 mm) from the adjacent finished surface of the head (Figure 2). attached to cylindrical shells, headers or pipe as depicted in Figure 1. (d) The center of the butt weld to the shell shall be located at a distance not less than corner radius, r, as in (b)(4) above, see Figure 1. flange Rev. 3: For Information Only Change hub to flange in (f)(2) per comment by Parvan Chavdarov, member of BPV-I German IWG (2) For heads machined from a forged blank, the tensile test specimen shall be taken as close to the hub as practical (Figure 2) and may be located inside or outside of the hub. flange.
PROPOSAL PAGE 2 OF 5 (3) For heads with flanges formed by direct forging action, the specimen shall be taken from material in the flange or an extension of the flange (Figure 3). (4) One test specimen may represent a group of forgings provided they are of the same design, are from the same heat of material, and are forged in the same manner. (g) This Case number shall be shown on the Manufacturer's Data Report. Figure 1 Flat Head Dimensions t s r Flat head Not less than r Weld centerline Pipe, shell or header
PROPOSAL PAGE 3 OF 5 Figure 2 Flat Head Tensile Specimen Location Tension test specimen
PROPOSAL PAGE 4 OF 5 Figure 3 Flat Head with Flange Formed by Direct Forging Action Tensile Specimen Locations Permissible tensile specimen locations for heads with flanges formed by direct forging action Flange 1.71701" extension to accommodate tensile specimen Weld CL Weld bevel location
PROPOSAL PAGE 5 OF 5 THIS PAGE IS FOR REFERENCE ONLY RE: ASME Section VIII, Division 1, UW-13.3(f) See Endnote 68 below