Friday, May 6, 2011

Forged Branch Fittings of Piping

Continuing from the last chapter yesterday, now the Table of Piping Fundamental base on ASME will be more and more and still with Piping & Fabrication.

TABLE A2.13 Dimensions of Typical Commercial Straight Butt-Welding Tees
Forged Branch Fittings
Under the various pressure piping codes, branch connections may be made by welding the branch pipe or a welding outlet fitting to the run pipe, provided sufficient reinforcement is available to compensate for the material removed from the run pipe to create the branch opening. The reinforcement may be in the form of excess material already available in the run and branch pipes, or it may be added. At the writing of this book, national standards governing the dimensions, tolerances, and manufacture of welding outlet fittings had not been issued. However, MSS-SP-97, 1995, has been developed to cover forged-carbon-steel 90° branch outlet fittings in butt-welding, socket-welding, and threaded outlet ends. The standard provides essential dimensions, finish, tolerances, and testing requirements.
Because of the absence of strict standards, manufacturers produce welding outlet fittings of their own proprietary designs. These fittings must comply with the codes governing the systems in which the fittings are to be installed. The fittings, when installed in accordance with the manufacturers’ recommendations, include the required reinforcement. The dimensions of these fittings vary; standardized dimensions and properties must be obtained from the manufacturers. Also, designers must consider the appropriate parameters (e.g., stress intensification factors). Figure A2.4 shows several types of welding fittings, which are proprietary; the terminology used varies with the manufacturer. The fittings are produced in carbon and alloy steels under the ASTM specifications for forgings permitted by applicable codes.

TABLE A2.14 Dimensions of Typical Commercial Concentric and Eccentric
Butt-Welding Reducers

TABLE A2.15 Dimensions of Typical Commercial Butt-Welding Standard Caps

TABLE A2.16 Dimensions of Typical Commercial Butt-Welding Laterals

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