pipe specs

The ASME B16 series documents are standards. The ASME B31 series are Codes.

See below for examples:

ASME/ANSI B16.5 - 1996 - Pipe Flanges and Flanged Fittings

The ASME B16.5 - 1996 Pipe Flanges and Flange Fittings standard covers pressure-temperature ratings, materials, dimensions, tolerances, marking, testing, and methods of designating openings for pipe flanges and flanged fittings.

The standard includes flanges with rating class designations 150, 300, 400, 600, 900, 1500, and 2500 in sizes NPS 1/2 through NPS 24, with requirements given in both metric and U.S units. The Standard is limited to flanges and flanged fittings made from cast or forged materials, and blind flanges and certain reducing flanges made from cast, forged, or plate materials. Also included in this Standard are requirements and recommendations regarding flange bolting, flange gaskets, and flange joints.

ASME B 31.3

ISBN #: 0791830403

Published: 2006
Product Type: Print-Book

The B31.3 Code contains requirements for piping typically found in petroleum refineries; chemical, pharmaceutical, textile, paper, semiconductor, and cryogenic plants; and related processing plants and terminals. This code prescribes requirements for materials and components, design, fabrication, assembly, erection, examination, inspection, and testing of piping. This Code applies to piping for all fluids including: (1) raw, intermediate, and finished chemicals; (2) petroleum products; (3) gas, steam, air and water; (4) fluidized solids; (5) refrigerants; and (6) cryogenic fluids. Also included is piping which interconnects pieces or stages within a packaged equipment assembly.

http://www.engineeringtoolbox.com/pipes-codes-standards-t_17.html

More specifically:

http://www.engineeringtoolbox.com/asme-b31pressure-piping-d_39.html

http://www.engineeringtoolbox.com/ansi-b16-pipes-fittings-standard-d_215.html