Gerry Groen, Ernest Lever, Oren Lever
Papers # 2016 Berlin
A design justification for reinforcement of fabricated Polyethylene elbows is presented. The acceptance criteria is that the average stress in the mitered wall of fabricated elbow shall not exceed the hoop stress in the matching pipe.
ASTM and ISO standards have established requirements for the geometry, production process verification, and QC testing of fabricated elbows but no design justification other than a history of successful use and the possibility of stress regression testing has been available as a means of verifying the amount of wall thickness reinforcement that is required. A PPI task group has been working with the Gas Technology Institute (GTI) to complete an FEA based ‘Virtual Design of Experiments’ in order to understand how a particular design behaves. A large number (exceeding 350) non-linear finite element analyses were conducted to evaluate the performance of various configurations of fabricated PE4710 elbows. The results of the analyses will be presented along with some examples of reinforcement calculations for both ID reinforced and OD reinforced elbows.
