Use of PE100 with a Minimum Required Strength (MRS) and Categorized Required Strength (CRS) Rating in a Natural Gas Distribution System

Session 11B
5:10 pm

Dr. Gene Palermo, Palermo Plastics Pipe Consulting

Manitoba Hydro is the electrical and natural gas utility for the province of Manitoba. A project to expand the existing system was initiated in 2005 which required the installation of a 29 kilometer main to connect a new town to the existing system. Options to provide this main including MDPE, HDPE, steel and PE 100 with a maximum operating pressure of 145 psig determined through a Minimum Required Strength (MRS) rating were investigated. The use of PE 100 was found to offer a $200,000 advantage over the second best alternative.

Manitoba Hydro’s gas distribution system is designed, constructed and operated under the requirements of CSA Z662 “Oil and Gas Pipeline Systems”. In 2005, PE 100 using an MRS rating was not included in Z662 as an approved material. A technical evaluation and material testing was performed. Based on the economic advantages provided and supported by the testing and investigation of the material, application was made to, and approval was received from Manitoba Hydro’s regulatory authority to install PE 100, pressure rated using an MRS. In summer of 2006, 29 kilometers of 114 mm SDR 11 PE 100 pipe was installed by plowing, horizontal directional drill and open cut methods. While system approval was obtained based on the MRS, the system was pressure tested based on a Categorized Required Strength (CRS) rating that could permit a future maximum operating pressure of 160 psi using the CRS rating method. This SDR 11 PE 100 pipe currently has a maximum operating pressure of 145 psig and has been successfully operating at pressures up to 135 psig. Manitoba Hydro plans to increase the pressure to 160 psig, based on CRS, when CRS is added to CSA B137.4.

Gene Palermo, Principal, Palermo Plastics Pipe Consulting
Tim Starodub, Gas Standards Engineer, Manitoba Hydro