Fastite Joint Pipe

Due to its high strength and stiffness with the resulting ability to support heavy earth and other type external loads, ductile iron pipe has found wide acceptance in gravity flow service such as sewer lines, outfalls and culvert pipe.

The problems of infiltration, root intrusion, and leakage are eliminated in sewer service with the use of the Fastite joint. The resistance of ductile iron to impact, the convenient pipe lengths, and the ease of assembly represent additional advantages of using ductile iron pipe in sewer service. In addition, ductile iron pipe has an inside diameter greater than nominal pipe size, which results in greater flow capacity with potential cost savings. Ductile iron pipe is available for normal domestic sewage service with cement lining. Other linings are available for sewer and special services. See Linings.

Ductile Iron Culvert Pipe

ASTM A716 is the standard for ductile iron culvert pipe covering sizes 14" through 64" manufactured per ANSI/AWWA C151/A21.51. AMERICAN ductile iron culvert pipe is furnished with Fastite or other suitable joints and is coated inside and outside with an asphaltic coating approximately 1 mil thick; or may be cement lined.

Minimum pressure classes are shown in this standard for sizes 14" through 64" for the range of cover from 2 to 41 feet, depending on size, based on Type 5 trench condition. This is the same Type 5 laying condition shown in current AWWA Standards C150 and C151. See Fig. 3-2. Pipe thickness for other conditions can be calculated by using formulas and design criteria in AWWA C150, except with modifications as specified in A716.

Ductile Iron Gravity Sewer Pipe

ASTM A746 is the standard for ductile iron gravity sewer pipe in sizes 4" through 64" with Fastite joints.

The design of AMERICAN ductile iron gravity sewer pipe in this standard is based on the same formulas and design criteria as pipe designed per ANSI/AWWA C150/A21.50, except that pipe with a flexible lining is designed with maximum allowable deflection of 5% of the outside diameter of the pipe instead of 3%. In the A746 Standard are thickness tables for cement-lined pipe and for flexible-lined pipe.

The thicknesses for cement-lined pipe will be the same as those in AWWA C151 for the same depths of cover and laying conditions. See Maximum Depths of Cover. The table below shows depths of cover for the different laying conditions for 4" through 64" pressure classes of flexible-lined pipe. The shaded areas indicate the depths of cover which are different from cement-lined pipe per A746 and from AWWA C151 as shown in Maximum Depths of Cover. These depths of cover are controlled by design deflection (instead of ring bending stress) and are greater than those for cement-lined pipe due to the 5% design deflection.

Gravity Sewer Pipe ASTM A746 Pipe with Flexible Linings
Depths of Cover for Standard Pressure Classes

1 Minimum allowable depth of cover is 3’.

2 Denotes the depths of cover resulting from the pipe thickness being governed by deflection in the design; these covers are greater due to the design deflection of 5% for flexible-lined pipe instead of 3% for cement-lined pipe.