Mears Group

Diameters and wall thicknesses of flexible pipes are usually designed as per hydraulic requirements, such as flow capacity, internal fluid pressure, and pipe material properties. Proper embedment is then designed to protect the pipe integrity against external loads. This paper considered engineering properties of embedment soils in analysis of flexible pipe-soil system for external load conditions and a new model was developed for the prediction of deflection of flexible steel pipe. Full-scale laboratory tests were performed to develop the new model and finite-element models were analyzed to validate the test results. In this research, the finite-element method was effectively used to model the soil-pipe interaction for five full-scale laboratory tests conducted on a steel pipe. Such models can be used for analysis of flexible pipe embedment design for layered embedment conditions. The results of finite-element analysis showed that the squaring of the pipe occurs when the haunch soil is weak compared to the side column. Another critical observation made during the tests was that the stresses at the bottom of the pipe and the bedding angle are highly dependent on haunch soil strength. It is desirable that the stress due to surcharge load on top of the pipe, weight of the pipe, and water inside the pipe be distributed uniformly across the width of the bedding.

Regulatory groups require gas storage facility operators to address the safety and environmental concerns that would be impacted due to a release of the processing fluid. The objective of this paper is to disseminate a process that operators can use to develop an ultrasonic thickness (UT) monitoring program with reliable and reproducible results that meet the fitness-for-service requirements set forth by industry. This paper targets Class 1, Type A components using a Level 1 assessment approach. These components represent the high risk assets subject to design equations that specifically relates to pressure and where supplemental loading does not govern required wall thickness, i.e. the required thickness is based on pressure only. A systematic approach to the organization and implementation of the program complete with mathematical equations to evaluate components for fitness-for-service requirements and justification for asset retirement is provided.

Assessing integrity and maintaining CP on an entire pipeline system can be a challenge under highly varying coating conditions, soil conditions, and CP requirements. Every pipeline operator has numerous projects competing for funding and resources necessary to maintain the entire system. Any remediation upgrades should be geared toward the following goals: Evaluate the general coating condition of the pipelines within a given scope.Assess the overall integrity.Achieve a level of CP that meets industry and regulatory requirements. This paper will discuss results of a challenging CP Remediation project including 175 miles of pipeline aimed at shifting the polarized potentials to a level more negative than -0.850 V CSE along the entire pipeline corridor while assessing integrity to assure the system is fit for service. Various CP Remediation methodologies will be discussed to highlight the importance of a well-rounded approach.

This paper describes the methodology used to identify and prioritize mitigation locations of potential interference from high voltage alternate current (HVAC) transmission line on a large pipeline transmission system in the United States. Satellite imagery with pipeline and HVAC transmission line GPS coordinates overlaid was first used to develop a database of potential locations. The database included the geophysical relationship of the location (pipeline/HVAC line geometry), pipeline coating type, HVAC line voltage, tower/circuit geometry and site soil resistivity estimate. A followed algorithm was developed using this information to calculate and rank the relative interference risk for each identified location. The algorithm included three primary risk factors; steady state induced and fault personnel safety, induced AC influenced corrosion and fault arcing pipe wall/coating damage.