Review of pipeline coating systems from an operator's perspective

Abstract

Over the past 40 years, pipeline integrity has been maintained by the simultaneous application of protective coatings and cathodic protection (CP). There have been significant developments in pipeline coating technology over the last 30 years as the traditional coating systems such as coal tar enamel, asphalt and single-and two-layer polyethylene (PE) coatings have been replaced in favour of coatings such as single and dual layer fusion bonded epoxy and three-layer PE and polypropylene. New coating technologies inevitably bring with them new problems for pipeline operators. The present paper reviews the transition from the more traditional coating systems to the second and third generation of pipeline coatings and discusses the new challenges that pipeline operators face. The difficulties of selecting field joint coatings with similar performance to the newer mainline coating systems will also be discussed, as well as issues related to electrical interference (ac and dc) and CP shielding that have become more of a concern because of the high integrity and dielectric strength of some modern coatings. Lessons learned over the years will be reiterated, and how far the pipeline coatings industry has progressed will be reflected upon.

Study of cathodic protection shielding under coating disbondment on pipelines

“…It is generally accepted [13] that the widely used fusion bonded epoxy (FBE) and coal-tar enamel coatings exhibits evidence of passage for CP current, while the high performance composite coating and polyethylene tape block CP current in long-term tests [13]. There have been works to measure and model environmental chemistry and electrochemistry of the electrolyte trapped under CP shielding or non-shielding coatings [14][15][16][17].…”

Crack Growth Sensitivity to the Magnitude and Frequency of Load Fluctuation in Stage 1b of High-pH Stress Corrosion Cracking

“…For the plane stress condition, like the stress condition on the free surface, yielding occurs when σ y equals the yield strength of the material. Assuming that the boundary between elastic and plastic occurs when the stress satisfies the yield criterion, the first-order estimate of the plastic zone can be calculated by Equation (5). It is worth mentioning that this equation is identical to Equation (3) on the crack plane (θ = 0).…”

“…For instance, pipes are protected against corrosion with the simultaneous application of cathodic protection and coatings to isolate the pipe from the local corrosive environment. [4][5][6][7][8] However, failure in the coating might result in the formation of occluded environments at the coating defect that are breeding grounds for environmentally assisted cracking (EAC).…”

Corrosion-mechanical behavior of gas main steel in saline soils

“…It can be noted that in case of damage to insulation and the absence or improper quality of active corrosion protection, thinning in chloride environments in the area of operational loads can reach 0.45-0.55 mm, and taking into account the localization process in case of ME3 it exceeds 6 mm/year, which testifies for the considerable danger of overpressure of pipelines, especially those that are used from 15 to 25 years with obsolete and degraded bituminous corrosion-resistant coatings [25][26][27][28]. It is particularly important to conduct groundwater analysis along pipelines' routes in order to timely assess the risks of corrosion degradation of steel pipelines and prevent depressurization, or more severe failures and emergency situations [29,30].…”