Sunday, March 17, 2013

Types of Bolting with It's Specifcations

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Bolting material for cast-iron flanges is listed in ASME B16.1. Generally, ASTM A307, grade B material is suitable. For steel flanges, acceptable bolting material is listed in ASME B16.5.

Threading: Bolts and nuts normally are threaded in accordance with ASME B1.1 Standard for Unified Screw Threads. In diameters 1 in and smaller, Class 2A fits on the bolt or stud and Class 2B on the nut applies with the coarse thread series. In diameters 1¹⁄₈ in and larger, the eight-pitch-thread series applies with the same fit. Grade 7 bolts are threaded by roll threading after heat treatment. Roll threading cold-works the surface uniformly.

Sunday, March 10, 2013

Joining Ductile Or Cast-Iron Pipe - Part 2

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This article is in continuation to Joining Ductile Or Cast-Iron Pipe - Part 1. Please go through part 1 before reading this.

Mechanical Screw-Gland-Type Joint

This type of mechanical joint for cast-iron pipe makes use of a coarse-threaded screw gland drawn up by means of a spanner wrench to compress a standard rubber or composition packing gasket. The joint allows from 2 to 7 angular deflection, as well as expansion or contraction without danger of leaks. A lead ring, inserted in the bell ahead of the gasket, seals off the contents of the line from the gasket. The ring also provides an electric circuit through the joint for thawing out frozen underground mains and service lines by the electrical method. The screw-gland joint is used in piping which conveys water, gas, oil, and other fluids at considerable pressure. The gaskets and lead rings are interchangeable with those used in equivalent lines of mechanical joints of the bolted-gland type. A full line of fittings is available for use with screw-gland pipe.

 

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