Optimizing the Design of Subsea Tie-in Spools by Using Different Mathematical Approaches - Literature review Example

Literature Review Name: University: Date: Optimizing the Design of Subsea Tie-in Spools by Using Different Mathematical Approaches – Literature Review Keijser and Douglas (2012) point out that every deepwater field development virtually relies on the pipelines. A pipeline failure because of an external event, defect, or corrosion could result in production loss and, sometimes contamination. Normally, pipelines failure is attributed to numerous causes, and the damage extent and type as well as depth of water wherein the failure happens demonstrates the way through which the repair could be done. As observed by Keijser and Douglas (2012), extensive damage of the pipeline could lead to adverse event at the time of pipelay operations. Normally, it is impossible to lift back the pipeline to the surface, and the pipeline section that has been damaged must be replaced subsea using a spool piece. These days, deepwater pipelines are tied routinely in as well as connected subsea by use of pipeline connection systems that are remotely operated and ROVs. The authors observed that the most economical and effective technique of adapting deepwater pipelines in order to facilitate the future subsea tie-ins entails utilization of modular units. In this case, the designer weld the sled into the pipeline juts like a normal pipe joint which is later installed through J-lay or S-lay. The installation of the new pipeline happens near the available pipeline while a jumper is used to perform the new tie-in, integrated to the diverless pipeline connectors. Furthermore, the midline tie-in sled is used for attaching the new tie-in at the new line’s pipeline end termination in addition to one end on the existing pipeline. The authors have presented a Perdido export line tie-in, which is a new pipeline connection hub for the future. This system experienced different shallow water tests and rigorous onshore SITs that led to a fruitful subsea installation in 1,372 meters water depth by utilizing different ROVs, with the HOOPS pipeline shutdown limited to 17 days. In Giordano, Guarracino, and Walker (2009) study, they focused on identifying test arrangement effects on the apparent strain level, rooted in the supposition of simple bending theory, whereby local buckling initiation happens. They observed that a systematic error can result from the test results scatter from various forms of testing arrangement, which are normally brought about by limitations on pipe ovalisation at the test rig’s loading and support points. According to the authors, the pipelines are purposely designed to have room for the effects associated with different loading conditions attributed to bending and pressure (internal and external), which includes the deformations at the time of setting up and operations. The pipelines’ design calculations as mentioned by the authors are intended for offering a robust and secure pipeline by economically utilizing the costly installation equipment and material. In the past, the pipeline design focused on limiting the stress approach; however, a limit state code was developed by DNV since 1996. A more wide-ranging basis for calculating the pipes’ ultimate conditions is realised by utilising limit state approach offers when subjected concurrently to bending as well as pressure loads. The concept of pipe’s ultimate states with ‘displacement-controlled’ and ‘load-controlled’ loading are some of the aspects included in the code. With the view to this, the authors observed that the deformations of the bending are influenced directly by the applied moments’ variations while the ultimate state is associated with the maximum moment condition. The authors concluded that the simplified engineering theory of bending general application could be flawed after imposition of ovalisation or, in contrast, the section’s boundary conditions could be limited from the ovalising deformations. The authors maintain that is an important limit state for designing the offshore as well as pipelines. Guarracino, Fraldi, and Giordano (2008) pointed out that the submarine pipelines design depends heavily on precise test results for the local buckling pipes’ collapse when experiencing the bending loading. In their study, the authors examine the anomalous values of compressive strains and axial tensile from test results, which are compared to the values which could be expected as a result of the simple bending theory. They utilized the finite element modelling to explain the cause of the distinctions flanked by the tests’ strain values as well as the anticipated on account of simple bending theory. According to the authors, the differences are attributed to the kind of supports and collars normally utilized in the bending tests, and the effects carry on for a bigger length along the pipe being tested. The bending tests results as pointed out by the authors demonstrated that based on the arrangement form at the load point as well as at the support, the compressive strains could be less or greater as compared to the related tensile strains, by approximately 30 per cent. The authors also observed that the local buckling initiation is prompted by the pipe wall’s compressive axial strain level. Therefore, the axial compressive strain variation because of the loading arrangement, specifically, the constraint level on the pipe’s ovalisation would influence the level of overall bending which could instigate local buckling. Because of the effects analysis attributed to the conditions of test loading, a considerable scatter component could be brought about by testing equipment differences. Based on the test arrangement effects in decreasing or increasing the test’s apparent buckling strain, calculations through utilization of buckling strain’s apparent values could lead to factors which are not associated with the projected probability failure level. The authors conclude that the test scatter attributed to various testing arrangement methods may consist of systematic error. In their study, Suman and Karpathy (1993) indicated that extensive thermal-stress analysis is needed for the thermal stresses management in subsea pipelines, especially those conveying heated petroleum so as to calculate trouble spots and also to make sure that the design is adequately flexible to expect expansions and stresses. The authors examined the different techniques for handling problems associated with thermal loads as well as the resultant deformations by ensuring that the pipeline system’s and stresses are within acceptable limits. The solutions presented by the authors related to the Asian subsea pipeline project. They observed that under design pressure, optimum viscosity must be maintained to facilitate flowing of crude oil through the pipeline. However, this relies on temperature and the proportionally is reduced since a lot of heat is reduced by heat. The authors point out that transporting high viscosity crude oil using subsea pipelines is very challenging. But efficient flow can be achieved by insulating the pipelines in order to reduce loss of heat as well as ensure that optimum viscosity is maintained. Based on the pipeline’s layout, length, and size as well as the ocean floor pipeline, limiting the pipeline expansion could result in disproportionate loads on the line. Such loads according to the authors, act at subsea tie-in or on pipeline connections next to pipeline end manifolds and platforms. For this reason, the design have to take into account the thermal growth as well as the resultant forces in order to make sure that the pipeline components’ stresses are within acceptable limits. In case the thermal expansion is limited, the authors posit that generation of large forces would happen in the piping components. Therefore, managing pipeline’s thermal forces as well as expansions should involve caution since many pipes as inherent metals property expand every time they are subjected to heat. Sparks (1984) posits that the effects of weight, pressure, and tension on various aspects of pipe have been studied extensively in the literature. But still, it is often misunderstood, occasionally with severe consequences. For this reason, the author tries to clearly discuss the subject using a very elementary approach. The author treats the principal problems of yielding, strains, bending, buckling, and buckling homogeneously. It was observed that for many years ‘effective tension’ has been utilized to simplify the problems of bending as well as buckling. Besides that, utilization of effective stress to examine certain problems associated with elastic tubes is not new in literature. But the literature has not adequately interpreted these concepts. The author observed that considering a riser or pipe as a composite column fabricated of internal fluid column(s) and pipe wall(s), effective tension when there is no external pressure is the composite column’s real total axial force. Effective tension when the external pressure is present is considered to be the difference between the displaced fluid column’s total force as well as datum force. The author has also given the effective stress a physical interpretation. In the elastic tube this stress is the deviator stress, which is the difference between the external and internal pressures induced axial stress and the in-wall hydrostatic stress. In this case, end effect stress and hydrostatic stress are equal. In their study, Liu, Liu, and Zhang (2009) maintain that the analysis methods of traditional pipeline design that are presented in different codes are normally rooted in limit stress standard. Still, such techniques could be inappropriate to contemporary steels, particularly for ground displacement load and other displacement controlled loads. Given that the oil and gas pipeline industry is developing rapidly, the focus has shifted towards the high-operating-pressure, large diameter, and long-distance. According to the authors, this has created need for corresponding guidelines for pipeline design while the criteria must focus on adapting the new situation. The designers should not only ensure that the pipeline is reliable and safe, but also efficient and economical in terms of operation. The authors maintain that the majority of the modern-day pipeline design codes focus on limiting the stress criteria. This is deemed satisfactory for steel having well defined yield strength and ductility as well as yield point. Under some load like landslides and earthquake, however, the pipelines’ stress could surpass the limit; thus, making the strength design criteria rooted in the stress invalid. The pipeline loading could involve both displacement and load controlled. While the pressure loading is considered to be load controlled the motion of soil surrounding the pipeline is normally displacement controlled. The contemporary construction of subsea pipeline according to Kershenbaum, Mebarkia, and Choi (2003) incorporates the new development fields that normally spread towards the seismic active zones. Such offshore zones involve the far-east and Southeast Asia as well as west-north and west America. Basically, the new fields positioned in areas having high earthquakes probability put offshore pipeline integrity and operational stability at risk. The authors established that the new seismic design demonstrated an improvement in the unburied pipeline’s seismic displacement leading to an extremely small increase in total longitudinal stresses as we; as pipeline bending. This was attributed mainly to the nonlinear relationships in pipeline stress and deflection. The pipeline snaking analysis main objective is determining the shape of the unburied pipeline that precedes the seismic impact. More importantly, the pipeline seismic stresses rely on the pipe axis initial shape. The unburied pipeline happens at a particular distance from the unrestrained end of the pipeline and increases gradually towards the pipeline restraint. As mentioned by the authors, the pipeline seismic loading major contribution is achieved through longitudinal ground displacement. Normally, this effect happens to pipelines that are already snaked and in close to the pipeline restrained section. As a typical subsea product, Ju, Fang, Yin, and Jiang (2014) posit that the subsea dynamic riser base (SDRB) is a crucial floating production system’s equipment piece. More importantly, it is considered as a vital anchor point not just for the cable transition to static but also dynamic riser. On the SDRB, the one end of the process piping is attached to the rigid pipeline that conveys the thermal expansion load. On the other end, it is attached to the flexible riser conveying flexible riser dynamic load that determines process piping stress analysis complexity. The authors suggest that the typhoons must be considered with the view to South China Sea due to their enormous impact on the riser systems dynamic response concerning the floating platforms motion. In addition, the authors believe that more attention be directed towards the SDRB piping stress analysis while the SDRB piping system must be optimized to effectively handle the riser system reactions. While performing the PIP piping stress analysis, it is imperative to test the entire system as well as key components using the general finite element software. With the view to the SDRB process piping, the authors suggest that forces should be carried from static loads and dynamic riser system and the piping support should be fixed at the riser side. Offshore subsea pipelines transporting oil and gas between subsea structures or offshore platforms according to Choi, Do, and Na (2010) are normally set up within the surrounding environment. At the time of operation, the authors posit that the inlet temperature increases dramatically leading to the increase of the whole line and press pipelines pressurization of the pipelines. Because of the increment of pressure as well as temperature, expansions of the pipelines happen simultaneously and longitudinally. Still, the resistance towards the expansion is attributed to the frictional contact between the seabed soil and subsea pipelines. The authors argue that if the longitudinal force on pipelines because of expansion is higher as compared to soil friction induced resistant force, the expansion happening in the pipelines is conveyed to the platform by means of subsea pipelines and his result in the damage and overload to subsea structures or offshore platforms. The expansion effect can be mitigated and prevented by installing the expansion spool between subsea pipeline as well as riser on the platform. The expansion of the pipeline because of the pressure and temperature would generate a soil friction force proportional to the length of pipe’s moving portion. References Choi, H.-S., Do, C.-H., & Na, Y.-J. (2010). Expansion Spool Design of an Offshore Pipeline by the Slope Deflection Method. Journal of Ocean Engineering and Technology, 24(5), 1-7. Giordano, F., Guarracino, & Walker, A. (2009). Effects of boundary conditions on testing of pipes and finite element modelling. International Journal of Pressure Vessels and Piping, 89, 196–206. Guarracino, F., Fraldi, M., & Giordano, A. (2008). Analysis of testing methods of pipelines for limit state design. Applied Ocean Research, 30, 297-304. Ju, X., Fang, W., Yin, H., & Jiang, Y. (2014). Stress Analysis of the Subsea Dynamic Riser Base Process Piping. Journal of Marine Science and Application, 13, 327-332. Keijser, E., & Douglas, G. (2012). Diverless technique adapted for deepwater repairs, future tie-ins. Offshore;, 72(8), 85-86. Kershenbaum, N., Mebarkia, S., & Choi, H. (2003). Behavior of marine pipelines under seismic faults. Ocean Engineering, 27, 473–487. Liu, B., Liu, X., & Zhang, H. (2009). Strain-based design criteria of pipelines. Journal of Loss Prevention in the Process Industries, 22, 884–888. Sparks, C. P. (1984). The Influence of Tension, Pressure and Weight on Pipe and Riser Deformations and Stresses. Journal of Energy Resources Technology, 106, 46-54. Suman, J. C., & Karpathy, S. A. (1993). Design method addresses subsea pipeline thermal stresses. Oil & Gas Journal, 91(35), 85-89. Read More