Description, Details and Accessories

The principal standards covering Flanged Pipe are ANSI/AWWA C115/A21.15 and ANSI/AWWA C110/A21.10. These and other standards are referenced throughout this Section either by the full ANSI/AWWA designation or by only the AWWA numbering, such as AWWA C115.

AMERICAN produces 4"-64" ductile iron flanged pipe with threaded flanges for water or other liquids in accordance with AWWA C115. Maximum length of flanged pipe is 17'6", 19'0", 19'6", or 20'0", depending on size; any length less than maximum can be furnished down to minimum practical lengths, varying also with pipe size. Flanges generally are threaded on all flanged pipe, except for short lengths of pipe which may be produced statically with integrally cast flanges as shown in Table Nos. 8-9 and 8-10; static castings are manufactured in accordance with applicable requirements of AWWA C110.

Flanged pipe is generally specified for aboveground service for air, water, sewage, oil and other liquids where rigid, restrained joints are needed. It is widely used in industrial piping systems, water treatment plants and sewage treatment plants, and for other interior piping.

Long runs of flanged pipe should normally include design provisions for thermal expansion and contraction, such as flexible joints or couplings at strategic intervals.

Pipe may be furnished with one end flanged and the other end with Fastite bell, mechanical joint bell, restrained joint bell, plain end, grooved or shouldered end, or with other type end as may be required.

The underground use of the flanged joint is generally not recommended due to the rigidity of the joint as noted in appendices of appropriate ANSI/AWWA standards.

Flanged pipe is rated for a maximum working pressure of at least 250 psi as specified in the tables in this Section. The AWWA C110 and C115 flanges (as well as the flanges faced and drilled per ANSI B16.1 Class 250) are also rated for maximum water working pressure of at least 250 psi. The flanges faced and drilled per ANSI B16.1 Class 250 are special; they do not match other flanges and are infrequently furnished. AMERICAN furnishes these only as a transition from equipment with these flanges to regular AWWA C110 or C115 flanges. These flanges faced and drilled per ANSI B16.1 Class 250 are shown in Table Nos. 8-11, 8-12 and 8-13. AMERICAN flanged pipe in sizes 24" and smaller is rated for 350 psi working pressure only when AMERICAN Toruseal® gaskets are used. In some cases other sizes of flanged pipe have been supplied for working pressures greater than 250 psi, again when joined with AMERICAN Toruseal® gaskets. Check AMERICAN for details.

Coatings and Linings

The standard outside coating for flanged pipe is a one-mil-thick asphaltic paint, but other outside coatings can be furnished when specified. While other linings are available as described in "Linings," cement lining, per AWWA C104, is usually furnished in flanged piping. Where AMERICAN is given the option, flanged pipe is normally furnished cement lined depending on availability.

A rust preventive coating is applied to the machined faces of the flanges; 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 for threading on ductile iron pipe are ductile iron in accordance with AWWA C115. (AMERICAN recommends only ductile iron flanges for strength and safety, though AWWA C115 currently allows both ductile iron and gray iron flanges.)

Flanges conform to the chemical and physical properties specified for ductile iron fittings in AWWA C110.

The minus thickness tolerances of the pipe barrels are shown below.

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 end projects beyond the face of the flange; it is then machined to give a flush finish of the pipe end 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 to ensure leak-free fabrication.

1-Ductile iron flange; 2-Ductile iron pipe barrel; 3-AMERICAN Standard Pipe Threads, ANSI B2.1, adapted to ductile iron outside diameters; 4-Pipe end and barrel machined simultaneously to a flush finish; and 5-Shroud.

AMERICAN Flanged Pipe is shop fabricated in accordance with AWWA C115, 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 damaging the pipe and/or flange threads. If installation conditions require assembly of the flange on the job, the flange may be factory assembled to a "hand-tight" condition. This permits removal and re-assembly at the job site 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 tightening larger flanges at the job site.

JOINT MATERIALS

Joint materials are normally furnished for all mechanical joint bell openings on pipe or fittings. With the exception of AMERICAN Toruseal® gaskets specifically recommended for superior performance, flanged joint materials are not normally furnished by AMERICAN, although they are generally available from stock. See Table Nos. 8-2 in this section and 8-3 in Details and Accessories.

Since flanged bolts are not generally furnished by AMERICAN, the following is given for information only.

Bolts and Nuts

Size, length and number of bolts and nuts are shown in Table Nos. 8-3 (Details and Accessories-AWWA C110 or C115 flange) and 8-11 (Details and Accessories-flange faced and drilled per ANSI B16.1 Class 250). 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.

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 (i.e. spans involving 2 or 3 lengths of pipe) or with any underground flanges* that could be subjected to undesirable beam loading. Toruseal® gaskets are normally furnished of high-quality black, molded SBR rubber with required properties per ANSI/AWWA C111/A21.11. Standard Toruseal® SBR rubber gaskets are ANSI/NSF Standard 61 certified for contact with potable water. Other type rubber is available on special order. AMERICAN Toruseal® gaskets meet the description of specially designed gaskets shown in the appendices of AWWA C110, C111, and C115, and special gaskets shown in the body of AWWA C111.

*As noted in the appendices of appropriate ANSI/AWWA standards, the use of flanged joints underground is generally not recommended because of the rigidity of the joint.

Gaskets

AMERICAN Toruseal® gaskets are recommended for AWWA standard flanged joints in normal water and sewage service, unless otherwise specified by the purchaser or consulting engineer. Ring gasket sizes shown in Table Nos. 8-3 (AWWA C110 or C115 flange) and 8-11 (flange faced and drilled per ANSI B16.1 Class 250) are recommended. The ANSI B16.21 standard specifies the inside of 3"-12" non-metallic full-face and ring gaskets to be greater (the same as standard steel pipe outside diameters) than nominal. Any flat gaskets used for ductile iron flanged pipe must have "nominal" inside diameters as shown in the appendix of ANSI/AWWA C115/A21.15, not the larger inside diameters per ANSI B16.21. The larger I.D. gaskets per ANSI B16.21 are not recommended by AMERICAN.