An overview of new progresses in understanding pipeline corrosion

An approach to achieving the ambitious goal of cost effectively extending the safe operation life of energy pipeline to 100 years is the application of health monitoring and life prediction tools that are able to provide both long-term remnant pipeline life prediction and in-situ pipeline condition monitoring. A critical step is the enhancement of technological capabilities that are required for understanding and quantifying the effects of key factors influencing buried steel pipeline corrosion and environmentally assisted materials degradation, and the development of condition monitoring technologies that are able to provide in-situ monitoring and site-specific warning of pipeline damage. This paper provides an overview of our current research aimed at developing new sensors and electrochemical cells for monitoring, categorising and quantifying the level and nature of external pipeline and coating damages under the combined effects of various inter-related variables and processes such as localised corrosion, coating cracking and disbondment, cathodic shielding, transit loss of cathodic protection.

The effects of mechanical stress, environment and cathodic protection on the degradation and failure of coatings: An overview

Organic coatings have been used in conjunction with cathodic protection as the most economical method of corrosion protection by the oil and gas pipeline industry. In a bid to prolong the life of the pipelines, the degradation and failure of pipeline coatings under the effects of major influencing factors including mechanical stress, the environmental corrosivity and cathodic protection have been extensively investigated over the past decades. This paper provides an overview of recent research for understanding coating degradation under the effect of these factors, either individually or in combination. Electrochemical impedance spectroscopy remains the primary and the most commonly used technique of studying the degradation of organic coatings, although there have been attempts to use other techniques such as electrochemical polarization (both dynamic and static), electrochemical noise, Scanning Kelvin Probe, Fourier Transform Infrared Spectroscopy, Differential Scanning Calorimetry and Dynamic Mechanical Analyser. Major knowledge and technological gaps in the investigation of the combined effects of mechanical stress, environmental corrosivity and cathodic protection on coating degradation have been identified.

An overview of methods for simulating and evaluating pipeline corrosion

Steel pipelines, buried under the soil and protected by the combination of protective coatings and cathodic protection (CP), are used for oil and gas transportation. These pipelines are one of the critical infrastructures for energy transportation and therefore became lifelines of modern society. The deterioration of the external surfaces of transmission pipelines is a serious problem and is caused mainly by coating and/or CP failure leading to the loss of integrity of pipelines. To avoid such damage, there is a need of techniques which are able to locate active corrosion sites, monitor corrosion, and evaluate corrosion damage. Fundamental understanding of such processes occurring on coated pipelines (with various types of defects in coatings as well as pipe) in complex soil environment is necessary for the development of such techniques. Numerous laboratory techniques, i.e., electrochemical impedance spectroscopy based, polarisation measurements based, mathematical simulations, direct observation etc. have been used to develop fundamental understanding, simulate and evaluate corrosion occurring in oil and gas pipelines under various operating conditions. Given the complex nature of the pipeline corrosion, application of these laboratory techniques in field measurements as well as in understanding the corrosion mechanisms is lacking. This paper presents an overview of investigations, based on electrochemical techniques, for simulation and evaluation of pipeline corrosion in laboratory.

Analysis of lightning current characteristics to investigate lightning strike damages to energy pipeline

Australia is one of the most lightning prone area on earth. Lightning strikes have been identified as one of the most common cause of energy pipeline damage in Australia. Therefore, a suitable protection schemes and mitigation strategies against lighting strike damage is very important for Australian pipeline industry. There are a number of research on lighting protection of establishment such as, power systems, buildings, and telecommunications systems, however, very few publications could be found which discuss about protection of pipeline from lightning strike. Assessment of effects in buried pipeline, due to lighting strikes is important. Existing models do not account adequately the effect of the characteristics of soil breakdown channels intercepted by the buried object. This paper aims to investigate the characteristics of lightning current on metal object under the soil of strike point so that lighting attachment to energy pipeline could be understand and a protection technique could be developed. Along with lightning current characteristics, lightning attachment process, distribution method, soil resistivity, propagation of lightning current in soil with a buried pipeline, pipeline electrical properties and other related areas and technologies is explored. The study shows that though there are some research on characteristics of induced on simple buried structures like narrow telephone cable or residential gas pipe, but no substantial research have been done on large comparatively complex structures like buried energy pipelines. Also dynamic behavior of soil and the object to be protected not been considered in protections schemes and experiments.