AWWA C208

AWWA-C208

Dimensions for Fabricated Steel Water Pipe

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4.1 .1 3. 2 Wrought steel. In small diameters (4 in. to 24 in. [1 0 0 mm to 60 0 mm] ), steel butt-welding fttings in accordance with ASME B1 6.9 conform- ing to AS TM A23 4/A23 4M are available in schedules and grades suitable for the waterworks service and are often an economical alternative to fabricated elbows. Larger wrought steel fttings, up to 48 in. (1 , 20 0 mm), may be advantageous for applications where space is limited and the smaller footprint of the wrought steel ftting would be more appropriate. (Steel butt-welding fttings are available in sizes less than 4 in. [1 0 0 mm]. For these smaller fttings, the application of dimensions for 4-in. (1 0 0 -mm) fttings would be conservative.)

4.1 .1 3. 3 Fabricated elbows. Te following guidelines for dimensioning fabricated steel pipe elbows are recommended:

Referring to Figures 2C, 2D, 2E, and 2F,

1 . R is the recommended elbow radius.

2 . T is the tangent length of the elbow.

3 . S is the elbow inside segment length. Minimum S = 1 .5 in. (38 mm) or 6t, whichever is greater.

Note: Tis represents good practice to control welding stresses and dimen- sional tolerances.

4 . Defection angle of 22.5° maximum per miter weld is recommended. In no case shall the maximum defection angle exceed 30 ° per miter weld.

5 . L is the minimum recommended length of the elbow leg.

No te: Depending on the size of the radius, L may be less than T.

6 . Recommended two-, three-, four-, and fve-piece elbows: For ∆ ≤ 22.5 °, use two-piece elbow; k* = 1 .

For 22.5° < ∆ ≤ 45°, use three-piece elbow; k* = 2.

For 45 ° < ∆ ≤ 67.5 °, use four-piece elbow; k* = 3.

For 67.5 ° < ∆ ≤ 9 0 °, use fve-piece elbow; k* =  4.

*Note: For any elbow confguration k = (number of elbow segments) – 1 .

7 . n e is the diameter multiplier for calculating the radius of an elbow. Rec- ommended nefor water mains is 2.5 . In instances where n eis less than 2.5 , stress intensi fcation factors need to be addressed as outlined in AWWA Manual M1 1 . Values of n e shall not be less than that which achieves the minimum S value noted above.

Where:

R = n e Do

S = Do (2n e – 1 )tan[∆/(2k)]

L = ne Do tan[∆/2] – Do (n e – 0.5 )tan [∆/(2k)] + fDo

T = n e Do tan [∆/2]

Example: Given a 49. 75 -in. OD, three-piece, 45 ° elbow, with n e =2.5 .

22.5 ° < ∆ ≤ 45 °, therefore, k = 2

R = 2.5 (49. 75 ) = 1 24. 375 in.

S = 49. 75 [ 2(2.5 ) – 1 ] tan{45 /[2(2)] } = 39. 6 in.

L = 2.5 (49. 75 )tan(45 /2) – 49. 75 (2.5 – 0.5 )tan{45 /[2(2)] } + 0.1 43(49. 75 ) + 5 = 43.8 in.

T = 2.5 (49. 75 )tan[ 45 /2] = 51 .5 in.

In certain applications, compound elbows and reducing elbows may be used. See Figure 5 for geometric relationships of a reducing elbow. For computational methods and formulas for compound pipe elbows, refer to AWWA Manual M1 1 .

Dimensions of Steel Water Pipe Fittings

Notes :

1 . All dimensions based on outside diameter of pipe equal to nominal diameter, D, except dimensions for 1 2-in. nominal and smaller pipe, which are based on pipe OD noted.

2. For elbow dimensions, see S ec. 4.1 .1 3. 3 and Figure 2.
3. Add additional length to these dimensions when necessary for fanged, mechanical couplings, or bell and spigot joints, or as needed to meet other design conditions.

*Lateral dimensions given are for an equal diameter, 3 0 ° angle ftting. For an angle greater than 3 0 ° through 70 °, see equationsHinUISTeOc. N4.G1 . 7L. IFMoIrTaEngDle/Hs gOreNaGterCtHhEanN7G0 °P, uIPseEdFimITenTsIiNonGgiven for a tee.

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