Flanged Joint Pipe
AMERICAN produces 4" through 64" ductile iron flanged pipe in accordance with AWWA C115. The maximum length of flanged pipe is up to 20’0", depending on diameter. Flanges generally are threaded as per C115. Any configurations requiring static castings are in accordance with applicable requirements of AWWA C110.
Flanged pipe is generally specified for aboveground service for water, wastewater, air, oil and other liquids where rigid, restrained joints are needed. It is widely used in water and wastewater treatment plants, in industrial piping systems, and for other interior piping as well as for exterior applications such as bridge and other elevated crossings.
Pipe may be furnished with one end flanged and the other with virtually any AMERICAN joint as may be required.
The underground use of the flanged joint is generally not recommended due to the rigidity of the joint and as noted in appendices of appropriate ANSI/AWWA standards.
Flanged pipe is rated for a maximum working pressure of at least 250 psi. If higher ratings are needed, consult AMERICAN and we will evaluate the application and use of Toruseal gaskets. AWWA C110 and C115 flanges are flat-faced. ANSI B16.1 Class 250 flanges are also rated for maximum water working pressure of at least 250 psi. The flanges faced and drilled per ANSI B16.1 Class 250 flanges are raised-face and have a different bolt circle. Be careful when specifying or ordering those. You are invited to consult AMERICAN.
Coatings and Linings
Since most flanged pipe is in an exposed environment, the usual outside shop coating is Wasser FerroClad primer. Most all AMERICAN linings, including cement per AWWA C104, are available for flanged pipe. A rust-preventive coating is applied to the machined faces of the flanges, and this coating may be removed prior to installation.
Pipe Barrel and Flanges
Ductile iron pipe barrels conform to the requirements of AWWA C151. All flanges furnished by AMERICAN are ductile iron and in accordance with AWWA C115. AMERICAN recommends only ductile iron flanges for strength and safety, although AWWA C115 currently allows both ductile iron and gray iron flanges.
Pipe barrels and flanges have tapered pipe threads (NPT) in accordance with ANSI B2.1 adapted to the ductile iron pipe outside diameters. The flange is threaded onto the pipe and machine-tightened until the pipe barrel extends through the face of the flange; it is then machined to give a flush finish of the barrel and flange and to ensure that the flange face is perpendicular to the axis of the pipe. The flange is designed so that a shroud substantially covers the working threads of the pipe for thread protection. Prior to assembly of the flange on the pipe, a commercial-grade thread compound is applied to the threads.
AMERICAN flanged pipe is shop-fabricated, and threading at the job site is not recommended. Flanges furnished on pipe are not interchangeable in the field and generally cannot be removed after fabrication without damage. If installation conditions require assembly of the flange, it may be factory-assembled to a “hand-tight” condition. This permits removal and re-assembly in the field, at which time suitable thread compound must be used. “Hand-tight” flanges should be limited to 16" and smaller sizes because of the difficulty in properly tightening larger flanges.
With the exception of AMERICAN Toruseal gaskets recommended for superior performance, flanged joint materials are not normally furnished. See AMERICAN Toruseal Gaskets.
AMERICAN Toruseal Flange Gasket
The AMERICAN Toruseal flange gasket is available for improved joint performance. It is vastly superior to conventional full-face or ring gaskets. Although recommended for all normal water and sewer service, it especially must be used in demanding services such as very large diameter flanged piping, specially designed long-span installations, or with any underground flanges that could be subjected to undesirable beam loading. Toruseal gaskets are normally furnished of high-quality molded black SBR rubber with required properties per ANSI/AWWA C111/A21.11. Standard Toruseal gaskets are ANSI/NSF Standard 61 certified for contact with potable water. Other type rubber is available on special order.
Since flanged bolts are not generally furnished by AMERICAN, the following is given for information only.
Bolts and Nuts
See Bolts, Nuts and Studs for size, length and number of bolts and nuts. Bolts are specified in ANSI B18.2.1, and nuts are specified in ANSI B18.2.2. Bolts and nuts of low-carbon steel conforming to ASTM A307 are specified in the Appendix of AWWA C110 and C115 for flanged pipe when rubber gaskets are used. Nuts of regular or heavy hex design are used according to customer specifications. Also, per the Appendix of AWWA C110 and C115, high-strength bolts should not be used when a gray iron flange is involved in the connection.