Definite Advantages of Utilizing Integrated Multiple Indirect Inspection (IDi) Technologies to Survey a Newly Laid 3LPE Coated Cross Country Pipeline: A Case Study

Every scientific or engineering assessment made in today’s life is with respect to a specific approach — prescriptive or performance-based. In India for a newly laid pipeline (approx. 443 Km) — there are various prescriptive regulations ascertained by OISD and PNGRB for the pipelines’ safe routine operations. In a prescriptive system, it becomes mandatory for a pipeline owner to have the most accurate coatings and Cathodic Protection (CP) data irrespective of the external soil environmental conditions. This will also require the other external aggravators such as AC interference, Railway Crossings, Temporal phenomena etc. to be taken into consideration while the survey data is being collected. Only then sufficient data is available for the Owner to make correct integrity-based decisions and step forward towards a performance-based integrity management program. Hindustan Petroleum Corporation Limited (HPCL)-Rewari Kanpur Pipeline (RKPL) started the external line inspection (XLI) program as a prescriptive procedure for ascertaining the health of the in-place CP system and assess the integrity of the coating.This pipeline with length of approx. 443 Kms stretching across three (3) states of Haryana, Rajasthan, and Uttar Pradesh traverses through a truly varying surrounding soil and ambient environmental conditions. As per NACE Standard Practice SP0502, it is known that different aboveground survey tools are to be utilized by the pipeline owner for varying soil conditions. To overcome the complexity of dealing with varying environments, weather conditions (resulting in varying soil resistivity) for specific pipeline lengths to be surveyed by the various different technologies that may be applicable, HPCL-RKPL opted to deploy an integrated indirect inspection system which allows to perform the following aboveground surveys simultaneously, at the same time: DCVG, ACVG, ACCA (CAT), CIPS – AC & DC with all recorded raw logs for authenticity. Using these raw logs, HPCL-RKPL were able to ascertain few intricate concerns with the in-place CP system which would have otherwise been veiled. This was possible due to the extremely high frequency of data capture on several times per second basis. The integrated CP and Coating Integrity data also aligned and correlated very well with the historically conducted in-line inspection information. This paper shall discuss the unique findings obtained during the survey.

Study on hydrogen permeation behavior of X80 steel under AC stray current interference

Purpose Alternating current (AC) corrosion is a type of corrosion that occurs in buried pipelines under AC stray current interference, which can increase the hydrogen embrittlement sensitivity of pipelines. However, rare research works have been conducted on the hydrogen permeability characteristics of pipeline steel under AC stray current interference. The purpose of this paper is to study hydrogen permeation behavior of X80 steel under AC stray current interference. Design/methodology/approach In this paper, the hydrogen permeation behavior of X80 steel under AC interference is studied by AC hydrogen charging experiment in a dual electrolytic cell. The relationship between hydrogen evolution rate and hydrogen permeation flux is studied using the gas collection method. The difference between AC hydrogen permeability and direct current (DC) hydrogen permeability is also discussed. Findings The anodic dissolution caused by AC corrosion promotes the chemical desorption reaction of the adsorbed hydrogen atoms on the surface, reducing the hydrogen atom absorption ratio by 70%. When the AC is smaller than 150░ A/m2, the hydrogen permeation process is controlled by the hydrogen atom generation rate, and the hydrogen permeation flux increases with the increase in hydrogen atom generation rate. When the AC exceeds 400░ A/m2, the hydrogen permeation process is controlled by the absorption ratio. The hydrogen permeation flux decreases with the decrease in the absorption ratio. Under AC interference, there is a maximum hydrogen permeation flux that linearly correlates to the H+ concentration in the solutions. Originality/value The high-strength steel is very sensitive to hydrogen embrittlement, and X80 steel has been widely used in oil and gas pipelines. To date, no research has been conducted on the hydrogen permeation behavior of pipeline steel under AC interference, and the hydrogen permeability characteristics of pipeline steel under AC interference are not clear. The research results of this paper are of great significance for ensuring the intrinsic safety of high-strength pipelines under AC stray current interference.