Field joint coating of pipelines – effect of soluble salt contamination on 2-layer heat shrink sleeve performance

Frazer Howard Smith
  • Anti-Corrosion Methods and Materials, March 2016, Emerald
  • DOI: 10.1108/acmm-09-2015-1573

What is it about?

During offshore pipe-lay, pipe lengths with anticorrosion coating are welded together, and, to facilitate the welding process, the ends of the pipe remain uncoated. A wide range of field joint coating (FJC) types is available for coating this bare section, functioning in conjunction with the pipeline cathodic protection system to provide an anti-corrosion system or package. This paper relates to a study of the effect of salt contamination on the performance of two-layer type heat shrink sleeve field joint coating

Why is it important?

During offshore pipelay some operators continue to specify maximum salt contamination levels of 30 or 50 mg/m² for 'two-layer' type heat shrink sleeve (2LHSS) 'field joint coating'. Often resulting in costly cleaning methods and even production stoppages. This study provides evidence of the insignificance of higher salt contamination levels on the performance of two of the most common 2LHSS used for offshore pipelines, globally in the past decade. Salt contamination levels of up to 120 mg/m² were found to have no effect on peeling performance after accelerated ageing by hot water immersion.

Perspectives

Mr Frazer H Smith (Author)
UKZN

Offshore pipelay is a very expensive operation and the last thing that is needed during production is to slow or stop the process in order to achieve an unrealistic low salt contamination level specified by a cautious design house . It is well known that a low salt level is essential for high strength coatings such as epoxy (as used on 'three layer' type heat shrink sleeve field joint coatings). However this study determined that high levels of salt contamination (of up to 120mg/m²) had no noticeable effect on the performance of 'mastic type' two-layer heat shrink field joint coating.

The following have contributed to this page: Mr Frazer H Smith

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