Technical Blog

Uni-Bell has recently published a new document titled, Design and Installation Guide – PVC Fittings and Laterals for Solid-Wall PVC Sewer Pipe. The guide provides information on appropriate system design and proper installation of PVC fittings products where solid-wall PVC pipe is used in non-pressure applications.

The Ductile Iron Pipe Research Association promotes ductile iron as “stronger” than PVC. While it is true that side-by-side laboratory testing would give the nod to DI, laboratory strength does not always transfer to real life.

The PE industry has developed a new pressure-pipe material that has been described as “high-strength.” Although the words “high-strength” sound reassuring, the reality is that pipe made from PE4710 is anything but.

Plastics have a material property that sets them apart from the traditional materials that most engineers studied in school. For traditional materials, there is no distinction between short-term loading and long-term loading – the material responds the same in either case. For plastics, however, there is a significant difference: plastics can handle much higher short-term loads than long-term.

Attached is a two-page material comparison sheet that addresses some important issues in sanitary sewer pipe selection. The document also serves as a quick reference for comparing PVC and PP non-pressure pipe.

In the sustainability world, many manufacturers claim that their products are “green.” Often the evidence supporting these claims is flimsy at best. The recently published Environmental Product Declaration (EPD) for PVC pipe does not fall into this category.

External loads usually govern the design of non-pressure pipes. For PVC sewer pipelines, one of the acceptance tests to ensure proper installation has occurred involves pulling a deflection mandrel through the pipe. Product standards for PVC gravity sewer pipes typically provide calculation methods and tables for sizing of these mandrels

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.

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.