Reinforced Thermoplastic Pipe (RTP) is a new technology that is reducing the cost of constructing oil and gas gathering pipelines while improving reliability. RTP combines high performing materials such as bimodal high density polyethylene with high strength reinforcing fibers in a unique construction to create a spoolable high pressure pipeline system. The compatibility of high density polyethylene in general and RTP specifically with aromatic and cyclo-aliphatic hydrocarbons was previously only understood in a qualitative manner. A test program was conducted to determine an appropriate quantitative application envelope.
The test program consisted of exposing samples of high density polyethylene to various concentrations of aromatic and cyclo-aliphatic hydrocarbons at various temperatures. After the samples were saturated, mechanical properties of the samples were tested at a variety of temperatures.
The mechanical properties of the exposed samples and unexposed samples were compared in order to determine an appropriate application envelope. It was determined that as the temperature was increased, the effect of the aromatic hydrocarbons on the mechanical properties of high density polyethylene increased dramatically. The results allowed for the determination of acceptable concentration levels of aromatic and cyclo-aliphatic hydrocarbons at a variety of temperatures.
RTP provides solutions to many challenges associated with the construction of gathering pipelines including construction cost, availability of skilled labour and limited construction timeframes. It is currently being used in wide range of gathering applications. The conveyed fluid in many gathering applications includes some level of aromatic hydrocarbons and napthenes. The results of this study provide guidelines for determining the suitability of RTP for such applications given the concentration of aromatic and cyclo-aliphatic hydrocarbons and the operating temperature.