Effect of Over-Insertion and Over-Deflection on the Integrity of PVC Pressure Pipe: Numerical and Experimental Analysis

Gasketed joints are the most popular method for joining PVC pressure pipes for buried applications. While this method has proven to be very reliable over the years, it can be susceptible to installers "over-inserting" the spigot end of the pipe into the bells, which can introduce stresses into that area of the pipe. This is particularly common when mechanical means (such as backhoes) are used to assemble the pipe joints in the field. While the pipes are made with clear maximum insertion indications, installers often have trouble controlling the insertion depth, or are not properly trained to avoid over-insertion. These stresses, combined with excessive joint deflection (usually from installers trying to eliminate fittings), have been identified as a source of concern, therefore a research program, combining experimental testing and numerical simulations, was initiated to determine the magnitude and potential effect of these stresses on a typical PVC pipe installation. The FE results correlated with the experimental results showing that it is practically impossible to bring a PVC pipe to failure at the installation. Further, the results showed that only grossly inadequate installation procedures could have an effect on the long term integrity of the piping system. A design change to the bell end of the pipe was found very effective in reducing the risks of over-insertion and hence reducing further the risks of premature failure due to inappropriate installation methods.