Advanced Sealing Solutions for Non-Crude Hydrocarbon Services

Abstract

Three years ago, the Non-Pushing Secondary Seal (NPSS) technology was introduced to the pipeline industry and since then it has successfully addressed challenging pipeline services. Over 300 seals have been installed utilizing the NPSS technology on crude services across North America. The use of Non-Pusher Sealing Technology represents a novel approach to the pipeline industry and has proven to enhance the reliability of crude oil pipeline applications. The NPSS technology has been meeting the stringent environmental regulations and the demands of the operators for safe, reliable, performance. This unique Non-Pusher Secondary Seal elastomeric element stretches and compresses to take up shaft/axial movement experienced by the seal in certain pipeline services. The sealing faces of the non-pusher seal tracks each other while in operation while providing class leading emission containment. In pipeline services shaft shuttling can occur due to the unstable axial loading conditions during hydraulic upsets [1]. Hydraulic shaft shuttling would quickly wear an O-ring and fret the stub sleeve resulting in increased leakage and premature seal failure. Coatings under the dynamic O-ring have been used in the past to help reduce the fretting of the O-ring, but they do not hold up over the expected life of the seal. Even the hardest of coatings have shown not to last more than a year under shuttling conditions. When using the NPSS, hard coating of the stub sleeve is no longer required because there is no movement of the secondary seal under shuttling conditions. This saves time and cost during seal refurbishment. Figure 1.0 illustrates the Non-Pusher Secondary Seal (NPSS) used on a high duty single seal utilizing a dual bushing [2] as the containment device (API Plan 66A).