Tensile Strength of PVC and ABS Well Casing Joints

An experimental test program was conducted to determine the parameters influencing the short-term and long-term axial strength of polyvinyl chloride (PVC) and acrylonitrile-butadiene-styrene (ABS) well casing joints. Joint configurations tested include: bell couplings, slip couplings, male/female threaded couplings, and threaded casing. The effect of cure time and cure environment on solvent weld joints, torque on threaded casings, and time of load application on joint axial strength were evaluated. from axial creep strength data, a regression analysis was conducted to calculate proposed design stresses for thermoplastic well casing systems. Based on these design stresses, the commercially available thermoplastic materials and joint systems tested had adequate strength for dry string lengths for over 1,000 feet (300 m). The effects of a simulated blockage test were also evaluated.