Michael Attard

Comparison of Laboratory Methodologies to Evaluate Corrosion Inhibitors for Oil and Gas Pipelines

Abstract Experiments were carried out using a loop in three fields (gassy-oil, oily-gas, and oil-transmission pipes) under 17 operating conditions, using six inhibitors (three continuous and three ...

Comparison of Techniques for Monitoring Corrosion Inhibitors in Oil and Gas Pipelines

Abstract Addition of corrosion inhibitors is one of the common methods to control both general and pitting corrosion of oil and gas pipelines. Development of an integrity management program to control internal corrosion of such pipelines depends on our ability to monitor the efficiency of the inhibitor performance. Monitoring in an oil and gas pipeline is a complex process due to the multitude of conditions that exist in such an environment. In this paper, the reliability of weight loss, linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), electrochemical noise (EN), and externally mounted hydrogen probes for monitoring inhibitor performance in oil and gas pipelines is investigated.

State-of-the-Art of Thermal Spray Coatings for Corrosion Protection

ABSTRACT Thermal-spray coatings are widely used in marine structures including offshore pipelines without external cathodic protection (CP). Al, Zn and Zn-Al thermal-spray coatings protect steel by acting both as barrier coatings and as sacrificial anodes at local defects where corrosion would otherwise occur. Zn provides better galvanic protection whereas Al is better as a less-reactive barrier layer. Zn-Al alloys appear to combine the protective properties of both Zn and Al. Although further research is required in order to specify the optimal alloy compositions for specific applications, 85% Zn-15% Al alloy is widely used. The best long-term protection is provided by suitably primed, sealed, and painted thermal-spray coatings. Thermal-spray coatings of acceptable structures and properties can be produced by flame spraying (wire or powder), arc spraying or plasma processing. However, due to economical reasons low melting point metals and their alloys are sprayed either by arc or flame. Surface preparation is considered to be a key factor in the production of uniform high quality coatings with maximum bond strength. Also of equal importance are the control of process facilities, equipment selection, and quality of consumable material for applying thermal-spray coatings. Well-bonded, relatively dense, sealed coatings have the ability to provide effective long term corrosion protection (10-20 years), with minimum periodic maintenance. Standards for evaluating thermal spray coatings have recently been developed.

Evolution of External Pipeline Coatings for Corrosion Protection – A Review

ABSTRACT External surfaces of pipelines are protected from corrosion by polymeric coatings that have evolved in the industry over the past 60 years, beginning with asphalt and then coal tar coatings, followed by polyethylene, epoxy, and urethane coatings. When a coating degrades or fails, the type of coating has an effect on the generation of environments that can cause corrosion and stress-corrosion cracking (SCC). In this paper, the types of coatings, laboratory performance, field performance, and the state-of-the-art of various pipeline coatings are reviewed.

Metallic Under-Layer Coating as Third Line of Protection of Underground Oil and Gas Pipelines from External Corrosion

This paper presents the concept of introducing a third line of defense in the form of a metallic under-layer coating—in addition to the traditional polymeric coating and applied cathodic protection (CP)—to protect the external surface of oil and gas pipelines. The three levels of protection would be the metallic under-layer coating, the polymeric top-layer coating, and the applied CP. This three-level system would be beneficial when the applied CP current is shielded from the pipeline by a dis-bonded polymeric coating, thermal insulator, or highly resistive soil. Two different combinations of metallic under-layer and polymeric top-layer coatings are presented to demonstrate this concept: 48%Zn and 52%Al under-layer with four different top-layer coatings: fusion-bonded epoxy (FBE), composite, urethane, and coal tar epoxy. Urethane top-layer coating with four different metallic under-layers: 48%Zn-52%Al, 85%Zn-15%Al, Al, and Zn. The criteria for the successful application of this concept also have been desc...

Assessment of Hydrogen Uptake and Permeation in AHSSs

This study aims to develop novel experimental procedure that quantifies response of AHSSs with different microstructures, deformation status, and strength levels to hydrogen. The capacity for trapped hydrogen, kinetics of hydrogen absorption and loss, and hydrogen mobility are measured and analyzed by permeation tests. The experimental findings are discussed in terms of microstructural features for an interstitial free (IF) and a dual phase (DP) steels. Further, the density of trap sites and its effect on effective diffusivity of hydrogen in the steel are analyzed by means of a diffusion model.

Technical Note: Determination of Blister Formation of External Pipeline Coatings Based on Current Spikes in the Cathodic Disbondment Test

Abstract A modified cathodic disbondment (CD) test was carried out over a period of 14 months using 13 different pipeline coatings. During the test the current was recorded every 4 h. Certain types...

Selection of External Coatings for Northern Pipelines: Laboratory Methodologies for Evaluation and Qualification of Coatings

In the near future, the construction of northern pipelines for transmission of natural gas will begin in North America. Construction in the harsh northern climate, with temperatures as low as −45°C, and remote location will impose unique challenges with respect to protective coatings. It is critical that the design of coatings be adequate to protect the pipelines under long-term, severe environmental conditions, including the extreme climatic conditions that will apply in the North before the pipe is installed and operation begins. There are many quality coatings from which to choose for application on new pipelines. The main issue is in understanding how to select and use coatings on pipelines in new regimes (e.g. Northern pipelines), which may operate in a different environment than do existing pipelines. Uniform, standardized tests that would simulate the conditions during construction and operation of Northern pipelines will allow external pipeline coatings to be selected with confidence regarding anticipated long-term performance under operational conditions. Selection of mainline coatings is important, but there is also a need to focus on field-applied coatings for both repairs and joints. Methodologies and standards that are available to evaluate coatings are reviewed in this paper.Copyright