ASME SECTION IV-2008 pdf download

ASME SECTION IV-2008 pdf download.RULES FOR CONSTRUCTION OF HEATING BOILERS.
HG-327 STRENGTH OF REINFORCEMENT HG-327.1 Strength of Nozzle and Added Material. Material in the nozzle wall and added material used for reinforcement shall preferably be the same as that of the boiler shell, but if material with a lower allowable stress value is used, the area provided by such material shall be increased in proportion to the inverse ratio ofthe allowable stress values ofthe reinforcement and the boilershell mate- rial. No advantage may be taken of the increased strength of reinforcement material having a higher allowable stress value than the material of the boiler shell. Deposited weld metal outside of either the boiler shell or any reinforcing pad used as reinforcement shall be credited with an allow- able stress value equivalent to the weaker of the materials connected by the weld. Boiler-to-nozzle or pad-to-nozzle attachment weld metal within the pad may be credited with a stress value equal to that of the boiler shell or pad, respectively. HG-327.2 Strength ofAttachment Material. On each side of the plane defined in HG-326.1, the strength of the attachment joining the boiler shell and reinforcement or any two parts of the attached reinforcement shall be at least equal to the smaller of (a) the strength in tension of the cross section of the element of reinforcement being considered. (b) the strength in tension ofthe area defined in HG-321 less the strength in tension of the reinforcement area that is integral in the boiler shell as permitted by HG-326.4. (c) the strength of the attachment joint shall be consid- ered for its entire length on each side of the plane of the area of reinforcement defined in HG-326.1. For obround openings, consideration shall also be given to the strength of the attachment joint on one side of the plane transverse to the parallel sides of the opening that passes through the center of the semicircular end of the opening. 21 HG-328 REINFORCEMENT FOR MULTIPLE OPENINGS HG-328.1 When Limits of Reinforcement Overlap. When any two adjacent openings are spaced at less than two times their average diameter so that their limits of reinforcement overlap, the two openings (or similarly for any larger group of openings) shall be provided with rein- forcement in accordance with HG-321 with a combined reinforcement that has a strength equal to the combined strength of the reinforcement that would be required for the separate openings. No portion ofthe cross section shall be considered as applying to more than one opening or be evaluated more than once in a combined area. HG-328.2 Combined Reinforcement for Multiple Openings. When more than two adjacent openings are to be provided with a combined reinforcement, the minimum distance between centers of any two of these openings shall preferably be at least 1 1 ⁄ 2 times their average diameter, and the area of reinforcement between them shall be at least equal to 50% of the total required for these two openings. (a) Two adjacent openings as considered under HG-328.2 shall have a distance between centers not less than 1 1 ⁄ 3 times their average diameter. (b) In lieu of providing reinforcement for individual openings, reinforcement may be provided for any number of closely spaced adjacent openings, in any arrangement, by providing reinforcement for an assumed opening of a diameter enclosing all such openings. (c) When a group of openings is provided with rein- forcement by a thicker section butt welded into the shell or head, the edges of the inserted section shall be tapered as prescribed in HW-701.1. HG-328.3 When Reinforcing Each of a Series of Openings Is Impractical. When there is a series of tube openings in a boiler and it is impractical to reinforce each opening, the construction will be acceptable provided the ligaments between openings are calculated by the rules given in HG-350. HG-330 INSPECTION AND ACCESS OPENINGS HG-330.1 General Inspection Openings (a) All boilers shall be provided with suitable manhole openings and handhole or washout plug openings to permit inspection and removal of accumulated sediment. (b) Electric boilers of a design employing a removable cover that will permit access for inspection and cleaning and having an internal gross volume (exclusive of casing and insulation) of not more than 5 ft 3 (0.14 m 3 ) need not be fitted with washout or inspection openings.