Handbook Plastic Pipe Ring Stiffness part 4
3.1 Determination of ring stiffness under use of pipe segments
In the following abstract the most important details of the procedure acc.
GIN 16917 are explained.
A mathematic investigation has proven that there exists a relationship between testing 79° pipe segments and the standard test procedure according to DIN EN ISO 9969. The same ring stiffness can be calculated. However, it is recommendable to also apply other testing procedures under prevailing working conditions and profile types before this alternative method is exclusively taken. A comparison and evaluation of the result of both methods is recommended.
The ring stiffness test acc. DIN 16917 is carried out with 79° segments, extracted from one pipe. The procedure correlates with DIN EN ISO 9969 in terms of setup and implementation and simply uses another test body. Instead of using a complete pipe, pipe segments are used. References on testing equipment, test body width, conditioning and implementation can be viewed in DIN EN ISO 9969. The cutting of the support surfaces of the segments must be carried out with special care because the bearing must be rigidly supported. Another crucial point, which should be treated with special care, is plane parallelism.
The ring stiffness is defined by measuring of strength and deformation under a constant deformation rate. Therefore, a pipe segment is used instead on a complete pipe. The pipe segment is deformed vertically under a constant rate. The deformation of a segment corresponds to the amount of deformation of a complete pipe (3%).
The test body (79° pipe segment) is pressed together at a constant speed acc. Specification of the standard ISO 9969. The measuring values of force and deformation has to be recorded continuously until a deformation corresponding to a deformation of the complete pipe of 0.03di is reached.