EVS-EN 9969:2008

EVS-EN ISO 9969 Thermoplastics pipes – determination of ringstiffness

European standard that sets the methodic for ring stiffness calculation for thermoplastic pipes with circumferential cross section. The methodic set differs significantly from the method described in German standard DIN 16961.
According to ISO 9969 the ring stiffness is determined my measuring the force applied to test piece to achieve predetermined 3% deflection of the test piece. Test piece is put between horizontal plates that move toward each other with continuous speed. The speed of the movement depends on the diameter of the pipe tested.
Force necessary to generate the 3% deflection of the test piece is the basis of the ring stiffness calculation formula.
The above described test is to be repeated on three test pieces and the average of the three tests is used for the actual calculation.