What Does Ring Stiffness Mean?
Ring stiffness of a pipe can be defined as its ability to resist radial forces acting on it and the pipes resistance to ring deflection and structural damage. This test is done as per American Society for Testing and Materials (ASTM) D2412 for thermoplastic and EN 1228 for glass reinforced plastic pipes (GRP). Buried pipes such as sewer and water pipes are subjected to soil pressure, hydrostatic pressure and live loads from traffic.
Tests to determine the ring stiffness of a pipe are carried out prior to burying them to ensure that the pipe material used can withstand expected soil conditions and loads when buried. It's advisable to carry out a ring stiffness test to prevent failure and costly rehabilitation of untested pipes when subjected to real loads.