Within the oil and gas industry there is an emerging trend to estimate expenses for pipelines and system components using a Life Cycle Cost (LCC) basis. This paper describes a new sizing model for swing check valves that can assist in significantly reducing the LCC of the valve. The incremental fuel cost of the compressor arising from pressure loss across the valve is the largest component of the valve’s LCC. The valve’s pressure loss can be minimized by correct valve sizing ensuring full valve opening under normal flow conditions.
This new sizing program, applied to an NPS 20 natural gas pipeline, can result in cost savings in the order of two times the capital cost of a swing check valve when compared to traditional sizing methods.
The pressure loss across the valve is primarily determined by the opening angle of the valve disc during steady state operation. A steady state valve model was developed and formed the basis for a sizing program for swing check valves. The sizing program assists in optimizing the valve for specified operating conditions. Within margins, the valve opening characteristic can be optimized by adjusting the valve sizing parameters such as valve size, disc weight, counter balance mass and position for a specified set of operating conditions.
The LCC of a swing check valve can be further reduced by up to 45% through optimization of the valve design. The sizing program was used in a parametric study to assess the areas relevant in the design optimization of the valve. To further reduce the LCC of swing check valves, research should focus on improving the internal flow profile of the valve, reducing disc weight and eliminating the need for counter balance weights through improving low friction seal design.
