Finite Element Analysis for Pipeline Leak Containment System

Abstract In this paper, the finite element analysis (FEA) for a proposed secondary containment assembly (Envirolock) intended to protect the environment from pipelines leaks was carried out. The assembly, composed from a Fiber Reinforced Polymer (FRP), aims to protect the most susceptible locations on pipelines where corrosion, dents and cracks could cause pipeline leaks to occur. The FEA was conducted to investigate the mechanical capacity of the system under hoop and longitudinal pressures. In the current study, the system was under full pressure emanating from a leak from the carrier pipe into the secondary containment liner. To explore the resistance capability of the containment system, which is composed of three layers (two polyurea and one carbon fiber), against internal pressure, finite element models were developed. Two separate finite element models for mid-pipe and end cap segments were created. System failure was defined as material failure, where failure pressure being the pressure at the onset of material failure in any layer. The FEA results indicated that the strength and failure of the mid-pipe segment under internal pressure is dominantly controlled by the carbon fiber layer. The failure of this layer will consequently lead to the failure of the polyurea layers. The carbon fiber makes the system capable of sustaining internal pressure (hoop stresses) up to 86 MPa. For the end cap FEA model, several consecutive trials and modifications were prototyped, and finite element models were created accordingly. The final design of the end cap has a cone-shaped geometry that is reinforced by different numbers and directions (acting in hoop and longitudinal directions), of carbon fiber layers wound over the surface of the end cap assembly. Based on the FEA results, the end cap segment of the containment system can sustain internal pressure of 21.5 MPa to 27 MPa depending on the number of CF layers. These results indicated that the containment system is safe to be used for most operating pressures of liquid and gas pipelines without compromising the assembly. The results of this FEA were used to finalize the design. The system passed ASME PPC-2 certification testing, the results of which can be used to finetune these FEA models. As more stringent rules and government regulations are enacted to enhance the protection of the environment, pipeline operators need to be proactive regarding public safety and the protection of the environment from pipeline leaks. This system is a risk mitigation tool containing pipeline leaks until further actions are implemented by pipeline operators. It also has the advantage of being a low-cost solution that can be installed on new or existing pipelines.