Title (English) Plastics piping and ducting systems – Thermoplastics pipes – Determination of ring flexibility (ISO 13968:2008); German version EN ISO 13968:2008
Title (German) Kunststoff-Rohrleitungs- und Schutzrohrsysteme – Rohre aus Thermoplasten – Bestimmung der Ringflexibilität (ISO 13968:2008); Deutsche Fassung EN ISO 13968:2008
Ring flexibility describes the ability of a pipe to withstand deformation without incurring structural damage. Measurement employs the same test arrangement as for ring stiffness. The test to ISO 13968 is continued up to failure of the pipe or until deformation of 30% of the pipe outside diameter has occurred. The result of the test is maximum force and deformation values, or force and deformation values at which a damage criterion defined in the standard first appeared.