TABLE 52.05-10 (a)-MAXIMUM ALLOWABLE STRESSES FOR FERROUS MATERIALS-Continued 1 In general, the allowable S values in table 52.05-10 (a), except for welded pipe and i Intermediate values of S may be obtained by interpolation. Carbon-molybdenum alloy-steel plate, pipe, forging, and cast material shall be The minimum tensile strength employed not given in the specification; tensile Permitted only for use as tube material in heat exchangers. This material shall be limited to a temperature of 875° F. when used in the design of pressure vessels. 1 Maximum allowable stress values for temperatures below 700° F. are as follows: These stresses include weld joint efficiency of 0.85. These stress values are limited in use to boiler, waterwall, economizer and super- 10 Between temperatures of -20° to 400° F., stress values equal to the lower of 11 This stress not permitted for temperatures exceeding 450° F. 12 To these stresses a quality factor as specified in § 52.05-13 shall be applied. 13 These stresses apply to the normalized material only. 14 This material limited to the construction of superheater, water wall and economizer headers when used in boilers. Where welding fabrication is employed, a minimum preheat temperature of 300° F. shall be used. For metal temperatures not exceeding °F. CODIFICATION: In § 52.05-10 (a) the table entitled "Table 52.05-10 (a)-Maximum Allowable Stresses for Ferrous Materials" was amended in its entirety by CGFR 54-2, 19 F. R. 726, Feb. 6, 1954, and subsequently further amended in the following respects: 1. Under the heading "Seamless alloy steel", item 51.34, the parenthetical references "(A206)", "(A280)”, “(A158)" and "(A315)" were deleted from column 2, A. 8. T. M. designation, by CGFR 55-46, 20 F. R. 8221, Nov. 2, 1955. 2. Under the heading "For metal temperatures not exceeding F."", the subheading for the first column was changed from "-20 to 650" to "650" by CGFR 57-48, 22 F. R. 9940, Dec. 12, 1957. 3. Following the last item under the heading "Seamless carbon steel", a new requirement, subpart "51.34", A. S. T. M. designation "A106", Grade "C", as set forth above, was added by CGFR 57-48, 22 F. R. 9940, Dec. 12, 1957. 4. Footnote 14 reading as set forth above was added by CGFR 57-48, 22 F. R. 9940, Dec. 12, 1957. § 52.05-12 Maximum allowable stress. (a) The maximum allowable stresses given in Tables 52.05-10 (a) and 54.0310 (c) in Part 54 of this subchapter may be used in the formulas for determining the maximum allowable pressure and the minimum thickness of seamless or arcwelded shells which do not require staying, unstayed blank hemispherical and ellipsoidal heads with the pressure on the concave side, flat heads which do not require staying, bolting flanges, and reinforced openings in shells and heads of boilers and unfired pressure vessels, provided the fabrication complies with the following requirements: (1) The pressure parts of boilers shall have a minimum thickness exceeding 1⁄2 inch, and to the calculated thickness as determined by the applicable design formula, a corrosion allowance of 0.1 inch shall be added. (2) The pressure parts of unfired pressure vessels shall have a corrosion allowance of one-sixth of the calculated thickness, or 16 inch, whichever is smaller, added to the calculated thickness as determined by the applicable design formula, except that no additional thickness need be provided when acceptable corrosion resistant materials are employed. (3) Backing strips fitted in way of longitudinal joints shall be removed and the weld surface and reinforcement of longitudinal and circumferential joints shall be prepared in accordance with § 56.05-5 (c) of this subchapter. For cylindrical shells subject to temperatures exceeding 800° F., all weld reinforcement on both the inside and outside of the shell at the longitudinal and circumferential joints shall be removed whereever possible. (4) Class II welded pressure vessels which are not given a complete radiographic examination shall have portions of the welded joints examined by spot radiography as required by § 56.05-6 of this subchapter. (5) The stresses due to hydrostatic head shall be taken into account in determining the minimum thickness of the shell or head of any pressure vessel. Additional stresses, imposed by effects other than internal pressure or static head, which increase the average stress over substantial sections of the shell or head by more than 10 percent of the allowable stress shall be taken into account. These effects include the weight of the vessel and its contents, method of support, impact loads, superimposed loads, localized stresses due to the reactions of supports, and stresses due to temperature gradient. (b) The maximum allowable stress used in the formulas for determining the maximum allowable pressure and minimum thickness of the following pressure parts of boilers and unfired pressure vessels shall not exceed 80 percent of the values given in Tables 52.05-10 (a) and 54.03-10 (c) in Part 54 of this subchapter: (1) Boiler shell or head thicknesses of 1⁄2 inch or less. (2) Riveted or brazed shells or heads. (3) Dished heads, other than hemispherical or ellipsoidal. (4) Unstayed hemispherical or ellipsoidal heads with pressure on the convex side. (5) Hemispherical and ellipsoidal heads with flanged-in or other unreinforced manholes. (6) All stays, braces or parts requiring staying. (c) Where the maximum allowable stress is limited to 80 percent of the values given in Table 52.05-10 (a) or 54.03-10 (c) in Part 54 of this subchapter, compliance with the provisions of paragraph (a) of this section is not required. [CGFR 55-23, 20 F. R. 4858, July 8, 1955] SUBPART 52.15-DOMES AND STEAM § 52.15-5 Materials and workmanship. (a) Steel plates used in the construction of domes and steam chimneys shall conform to the specifications and requirements for the shell plates. [Paragraph (a) amended by CGFR 54–2, 19 F. R. 727, Feb. 6, 1954] SUBPART 52.20-DISHED HEADS § 52.20-5 Materials and workmanship. (a) Steel plate used in the fabrication of dished heads shall conform to the specifications and requirements for the shell plates. Welding caps, conforming to the requirements of subpart 51.34 of this subchapter, may be used as end closures in water drums and headers, provided the diameter does not exceed 24 inches. Flanged or dished heads if pressed or 52.20-15 Detail requirements. (a) Where the radius R to which a dished head is formed is less than 80 percent of the inside diameter of the shell, the thickness of a head with a flanged-in manhole opening shall be not less than the value found by making R, in Formulas (1) and (2) in § 52.20-10, equal to 80 percent of the inside diameter of the shell and with the added thickness for the manhole. The thickness calculated shall be the minimum thickness of a head with a flanged-in manhole opening for any form of head and the maximum allowable stress shall not exceed 80 percent of the values given in Table 52.05-10 (a) or 54.03-10 (c) in Part 54 of this subchapter. (e) If a flanged-in manhole which meets the requirement of § 52.20-20 is placed in a full-hemispherical head or ellipsoidal head, the thickness of the head shall be the same as for a head dished to a segment of a sphere, with the radius of dish equal to eight-tenths of the inside diameter of the shell and with the added thickness for the manhole as specified in paragraph (d) of this section. [Paragraphs (a) and (e) amended by CGFR 63-25, 18 F. R. 7848, Dec. 5, 1953] (f) (1) Except as provided for in paragraphs (d) and (e) of this section, all openings which require reinforcement placed in an unstayed spherically dished head, or an ellipsoidal head, or in a fullhemispherical head, including all types of manholes except those of the integral flanged-in type, shall be reinforced in accordance with § 52.25-20. (2) When so reinforced, the thickness of such a head may be the same as for a blank unstayed dished head. 31048-59-8 (h) If more than one flanged-in manhole or access opening is inserted in a dished head, the thickness of which is calculated by paragraph (d) of this section, the minimum distance between the openings shall be not less than onefourth of the outside diameter of the head. [Paragraphs (f) and (h) amended by CGFR 55-28, 20 F. R. 4859, July 8, 1955] § 52.20-20 Openings in dished heads. (a) Flanged-in manhole openings in a dished head shall be flanged to a minimum radius measured on the inside of the plate of not less than % inch for plates up to and including 1% inches in thickness, and for plates exceeding 1% inches in thickness, the radius shall be increased proportionately. The minimum depth of the flange measured from the outside of the opening along the major axis shall be not less than three times the required thickness of the head for plate up to 11⁄2 inches in thickness, and for plate exceeding 11⁄2 inches in thickness, the depth shall be the thickness of the plate plus 3 inches. |