Quasi-static and dynamic indentation of offshore pipelines with and without multi-layer polymeric coating

Abstract

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.

Mechanical Modeling of the Polymeric Coating on a Subsea Pipeline

“…Coating specimens were retrieved from virgin pipeline samples from a production batch intended for operational use. Other pipeline samples from the same batch have previously been studied in terms of the coating products ability to absorb energy during impact events [2,6]. Previous studies [5] revealed a strong variation in the porous morphology throughout the thickness of the Porous PP with possible implications for the mechanical response (and thus energy absorption) of the full coating.…”

“…Extreme loading situations may be caused by impact from moving objects like fish trawling gear or falling anchors [1]. Vestrum et al [2] proved significant energy absorbing capabilities of a polymeric insulating coating during impact from moving objects. As both pipelines network systems and cross-section architectures are designed with respect to the likelihood and risks of such accidental events [3], a great economical potential exists in the inclusion of the thermal insulation during mechanical assessments.…”

Mechanical behavior of metallic strip flexible pipes during reeling operation

“…Compared to other types of composite pipe, MSFP has advantages in relatively cheap reinforcement material and a simpler manufacturing process, which results in low production costs. Thus, they are regarded as a popular choice for submarine pipelines transporting oil and gas [1,2].…”

Influence of the addition of multi‐walled carbon nanotubes on the thermal and mechanical properties of polyamide‐11 before and after aging tests

“…In this way, flexible pipelines can eventually present structural integrity problems causing production losses, accidents with fatal victims, and even environmental severe disasters, such as the spill of crude oil at sea. That is why its integrity must be preserved at all costs 4 …”

“…Polyamide‐11 (PA11) has been widely used by the oil industry, mainly in the barrier layer of these flexible ducts, with the function of ensuring the structure tightness 4 . The high proportion of hydrocarbons concerning the amide group (−[CH 2 ] 10 CONH–) in the PA11 chain results in excellent mechanical properties, like high fatigue resistance, low friction coefficient, and excellent chemical resistance.…”