Technical Blog

In 1975 AWWA published the C900 standard for PVC pressure pipe and fittings. The standard’s product sizes ranged from 4-inch through 12-inch. In 1988 a second PVC pressure pipe standard was published – this standard, AWWA C905, included sizes from 14- through 24-inch.

In 1980 ASTM published its F679 standard for solid-wall PVC pipe and fittings. The standard’s design philosophy was to allow two wall thickness options (called “T1” and “T2”) based on two values for the PVC material’s modulus of elasticity.

In 1980 ASTM published its F679 standard for solid-wall PVC pipe and fittings. The standard’s title, “Polyvinyl Chloride (PVC) Large-Diameter Plastic Gravity Sewer Pipe and Fittings,” was appropriate at the time, because the product sizes ranged from 18-inch to a maximum size of 27-inch.

Some project specs require Ductile Iron (DI) pipe because of its supposed “strength” in resisting external loads. In the past it was true that iron pipe had plenty of pipe stiffness, but that was before the iron industry converted from thicker-walled Class pipe to thinner-walled Pressure Class pipe.

In 1994 AWWA’s Research Foundation published a report on PVC pipe titled “Evaluation of Polyvinyl Chloride (PVC) Pipe Performance.” We have now reached the 29th anniversary of the study – time for a look back to see if the research findings were accurate.

Product standards for PVC water and sewer pipes typically require PVC materials to meet ASTM cell-class requirements. The cell class consists of five cells that designate different aspects of the material.

Each length of PVC pipe is required by its product standard to contain a line of print that describes the pipe.

his document compares two pipe materials for response to “occasional surge,” a term that might not be well understood. AWWA standards define “occasional surge” as: Occasional (emergency or transient) surge pressure: Surge pressures caused by emergency operations, usually the result of malfunction (such as power failure, sudden valve closure, or system component failure).

This tech brief focuses on the third method, axial deflection. Mathematically the idea is simple. For example, if you want to change direction by 5° and the allowable change in direction at each joint is 1°, then you need to deflect 5 joints.

During 60 years of sustained growth for PVC water pipe, iron pipe’s market share has decreased dramatically. The iron industry has reacted by negative attacks and by spreading misinformation about PVC pipe. I think it is time to provide more balanced information.