ASME SA-250 SA-250M-2021 pdf free.Electric-Resistance-Welded Ferritic Alloy-Steel Boiler and Superheater Tubes.
6. Chemical Composition 6.1 The steel shall conform to the requirements given in Table 1. 6.2 Product Analysis 6.2.1 An analysis of either one length of flat-rolled stock or one tube shall be made on each heat. The chemical composition thus determined shall conform to the requirements given in Table 1. 6.2.2 If the original test for product analysis fails, retests of two additional lengths of flat-rolled stock or tubes shall be made. Both retests for the elements in question shall meet the requirements of the specification; otherwise all remaining material in the heat or lot (See 8.1) shall be rejected or, at the option of the producer, each length of flat-rolled stock or tube may be individually tested for acceptance. Lengths of flat- rolled stock or tubes that do not meet the requirements of the specification shall be rejected.
7. Mechanical Requirements 7.1 Tensile Requirements 7.1.1 The material shall conform to the requirements as to tensile properties given in Table 2. 7.1.2 Table 3 gives the computed minimum elongation values for each 1 ⁄ 32 -in. [0.8-mm] decrease in wall thickness. Where the wall thickness lies between two values given in Table 3, the minimum elongation value shall be determined by the following equation:E 5 48t1 15.00 @ E 5 1.87t1 15.00 # where: E = elongation in 2 in. [50 mm] %, and t = actual thickness of specimen, in.[mm]. 7.2 Hardness Requirements—The tubes shall have a hard- ness not exceeding the values given in Table 4. 7.3 Mechanical Tests Required 7.3.1 Tension Test—One tension test shall be made on a specimen for lots of not more than 50 tubes. Tension tests shall be made on specimens from two tubes for lots of more than 50 tubes (See 8.2). 7.3.2 Flattening Test—One flattening test shall be made on specimens from each end ofone finished tube, not the one used for the flange test, from each lot (See 8.1). 7.3.3 Flange Test—One flange test shall be made on speci- mens from each end of one finished tube, not the one used for the flattening test, from each lot (See 8.1). 7.3.4 Reverse Flattening Test—One reverse flattening test shall be made on a specimen from each 1500 ft [450 m] of finished tubing. 7.3.5 Hardness Test—Brinell and Rockwell hardness tests shall be made on specimens from two tubes from each lot (See 8.2). 7.3.6 Hydrostatic or Nondestructive Electric Tests—Each tube shall be subjected to either the hydrostatic or the nonde- structive electric test. The purchaser may specify which is to be used.
8.2 For tensile and hardness test requirements, the term lot applies to all tubes prior to cutting, of the same specified outside diameter and specified wall thickness that are produced from the same heat of steel. When final heat treatment is in a batch-type furnace, a lot shall include only those tubes of the same size and the same heat that are heat treated in the same furnace charge. When the final heat treatment is in a continuous furnace, a lot shall include all tubes of the same size and heat, heat treated in the same furnace at the same temperature, time at heat, and furnace speed. 9. Forming Operations 9.1 Tubes when inserted in the boiler shall stand expanding and beading without showing cracks or flaws. Superheater tubes when properly manipulated shall stand all forging, welding, and bending operations necessary for application without developing defects.ASME SA-250 SA-250M pdf download.