SEDL / STP / STP787-EB / STP28500S

Testing of Buried Fiberglass-Reinforced Plastic Pipes

Galili, N
Visiting Associate Professor, Texas A&M University, College Station, Tex.

Shmulevich, I
Visiting Associate Professor, Texas A&M University, College Station, Tex.

Pages: 20    Published: Jan 1982

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Abstract

The design of buried fiberglass-reinforced plastic (FRP) pipe for cooling systems of power plants was tested experimentally. The tests were conducted in a soil-box, with a pipe specimen of 903 mm internal diameter and 9.92 mm wall thickness. The backfill material was poorly graded sand at three different densities. Radial deflections, hoop strains, and soil pressure distribution around the pipe were measured during backfilling and after over-pressures of up to ten times the design load (200 kN/m²) were applied. The test results were used to evaluate load concentration factors, circumferential bending moments, and total pipe deflections.

The results of the study showed that strains and deflections of the FRP pipe are primarily controlled by the type of backfill and its density. When properly installed, the deflections and the bending moments of the tested pipe were substantially lower than those calculated by conventional design methods, leaving a higher safety factor to assure long-term durability of the FRP pipe. The results also suggest that simple deflection tests made during construction may provide a complementary inspection method to ensure proper installation of the pipe.