Bolted Joints and Flanges in Piping Components

Bolted Joints and Flanges in Piping Components will talk in this topic of Piping & Fabrication and here we are;

Bolted Joints
The use of bolted joints is advantageous in the following circumstances:
•    The components cannot be serviced in line.
•    The components being joined are not capable of being welded.
•    Quick field assembly is required.
•    The component or pipe section must be frequently removed for service.
Bolted piping components are manufactured in accordance with several national standards. Also, several manufacturers produce proprietary bolted connections which offer cost and time savings over conventional flanged connections. However, proprietary designs must be used within the limitations of the applicable codes.

Ductile and Cast-Iron Flanges. 

Cast-iron flanges are produced in accordance with ASME B16.1. The standard establishes dimensional requirements, pressure ratings, materials, and bolting requirements. The pressure-temperature ratings and materials requirements for cast-iron flanges are the same as those for cast-iron flanged fittings. The pressure-temperature ratings are given in Table A2.6. Thedimensions for Class 125 and Class 250 cast-iron flanges are listed in Table A2.17. XDimensions for bolting are listed in Table A2.18. Note that the Class 125 and Class 250 flanges can be mated with ASME B16.5 Class 150 and Class 300 steel flanges, respectively. When a Class 150 flange is bolted to a Class 125 cast-iron flange (a flat-faced flange), the steel flange should be flat-faced. Ductile iron flanges and flanged fittings are manufactured in conformance with the following standards:
ASME B16.42 Ductile Iron Pipe Flanges and Flanged Fittings—Class 150 and 300.
ANSI/AWWA C110/A21.10, C115/A21.15 and C153/A21.53, are listed earlier under ductile and cast iron fittings.

Steel and Nickel-Alloy Flanges. 

Steel and nickel-alloy flanges up to NPS 24 are produced in accordance with ASME B16.5. Steel flanges NPS 26 (DN 650) through NPS 60 (DN 1500) are produced in accordance with ASME B16.47. Also, orifice flanges are produced in accordance with ASME B16.36. The standards specify materials, dimensions, pressure-temperature ratings, and recommendations for bolting and gasketing. Flanges manufactured to ASME B16.5 and B16.47 may be cast or forged. Also, blind flanges may be fabricated from specific plate materials. The most commonly used materials are forged carbon steel (ASTM A105) and forged low-alloy and stainless steel (ASTM A182). The standards cover seven pressure classes (Classes 150, 300, 400, 600, 900, 1500, and 2500) in a variety of styles and materials. Figures A2.16 and A2.17 show typical flange styles. The dimensions of each style within each pressure class are held constant irrespective of the material. Therefore, within each pressure class, the pressure-temperature rating varies with the material properties (see Figs. A2.1, A2.2, and A2.3).

TABLE A2.17 Dimensions of Typical Commercial Cast-Iron Companion Flanges
Manufactured in Accordance with ASME B16.1-1989

TABLE A2.18 Bolting Dimension for Cast-Iron Flanges