Offshore pipelines are occasionally subjected to accidental impact loads from trawl gear or anchors, which may damage the pipe. In this study, a series of indentation experiments carried out on offshore steel pipes covered by a multi-layer polymeric coating solution is presented. Polymeric coating solutions are often applied to pipelines to act as corrosion protection and thermal insulation. Despite not being designed for it, the polymeric coatings are experienced to have an energy absorbing capacity, which is the main topic of the investigation herein. In design codes and guidelines, coatings are traditionally not accounted for when determining the energy absorbed by a pipeline during impact. This makes estimates overly conservative. The main goal of this experimental work is thus to investigate the contribution a typical polymeric coating makes to the energy absorption in a pipeline during impact. To this end, a series of indentation experiments carried out on offshore steel pipes covered by a multi-layer polymeric coating solution is performed. The test program includes quasi-static and dynamic denting experiments on both coated and uncoated full-scale pipe cross-sections. All pipes tested have a length of approximately 1 m. The sharpest indenter from the relevant guidelines is used, as a sharp indenter is more likely to penetrate the coating compared with a blunter one. Based on the outcome of the tests, the polymeric coating is found to absorb a considerable amount of the kinetic energy delivered by an impacting object.
Accidents by trawling impact have the potential of environmental consequences, in terms of safety, monetary values and reputation. Aware of this situation a technology development plan on “Pipeline subject to high interference loads” has been established at STATOIL in close collaboration with GASSCO. The overall achievement is to adapt and introduce more reliable assessment methods in the load and response of pipelines under a trawling impact scenario. Polymeric coating systems have been manly designed and used as thermal isolating material for flow assurance; and little attention has been addressed to mechanical benefits to dissipate energy by large deformation. This property is of special interest to handle impact events typically found during the trawl board impact scenario. The experimental results show the beneficial effect of polymeric coating to protect the steel pipe against indentation when compared to an uncoated system. The results presented in this work focus on new developed analytical expressions to predict the force-dent response of polymeric coated steel pipes using a numerical-experimental research methodology. The proposed equations are validated against experimental tests and the findings indicate fairly good predictions.
Offshore pipelines are occasionally subjected to accidental impact loads from trawl gear or anchors, which may damage the pipeline. This study reports the results of material and component tests carried out on offshore steel pipes and an adhering polymer coating. The polymer coating is primarily applied for corrosion protection and thermal insulation. Despite not necessarily being designed for it, the polymer coating does have some structural capacity, and it is this capacity that is the main topic of investigation herein. In design codes and guidelines, coating is traditionally not accounted for when determining the energy absorbed by a pipeline during impact. This makes the estimates provided overly conservative. The goal of this experimental work is then to investigate whether a typical polymer coating makes any significant contribution to the energy absorption properties of a pipeline cross-section during impact. To this end, both dynamic and quasi-static denting tests of full-scale pipe cross-sections are carried out. All pipes tested have a length of approximately 1 m. The sharpest indenter from the guidelines is used, as a sharper indenter is more likely to penetrate compared with a blunter one. Based on the tests, the polymer coating can absorb a notable part of the kinetic energy delivered to the system. More tests with different coating and pipe thicknesses are needed to quantify this effect.
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