How much is pipeline corrosion affecting the oil and gas industry?

As worldwide demand for oil and gas continues to increase, it remains vitally important that supplies are able to reach the market both quickly and efficiently, for this, pipelines are vital in creating a significant transportation network - but therein lies a totally different problem.

Today, new pipeline projects are being fully welcomed by the industry, but in-line with this existing pipelines need to be maintained so that they stay fully operational and that pipeline corrosion doesn't become an issue.

Nonetheless, the oil industry's annual corrosion costs are estimated at about US$15 billion.

Some pipelines deteriorate slowly, and in certain cases pipeline life has been reliably targeted at 70 years or more. Other pipelines have been built which have exhausted their useful life after ONE year of operation, according to Corrosion Doctors.

Accurately tracking changes in corrosion rates is a serious challenge for gas pipeline operators.

Pipeline regulators require operators to demonstrate that corrosion rates are as low as two mils/yr. or less to ensure safe operation. Should the measured corrosion rate exceed two mils/yr., operators are required to take actions to mitigate the corrosion or effect repairs. While many approved technologies (e.g., corrosion coupons and electrical resistance (ER) probes) are available for measuring corrosion, most of these technologies measure the corrosivity of the gas rather than the changes in the pipeline wall. Because these methods infer the rate of corrosion of the pipeline indirectly, the accuracy of the measurements can be influenced by numerous factors.

What causes corrosion:

Corrosion is a natural process. The primary driving force of corrosion is based upon the transformation of iron from its natural state to steel.

* Stress corrosion occurs when even a very small pit forms in a metal under stress. The concentrated stress either deepens and extends the pit, or cracks the protective film which tends to form. Under continued exposure to the corrosive medium and stress, the crack extends by alternate corrosion and stress failure.

* Hydrogen embrittlement and hydrogen attack result when atomic hydrogen penetrates into the grain boundaries of steel producing microcracks, blistering and loss of ductility. The atomic hydrogen combines into molecules and results in blistering and laminations.

* Dissimilar soils can effect a buried pipeline, as they will encounter soils that have varying compositions.

How to protect pipelines:

Corrosion control of pipelines throughout the world is accomplished in the vast majority of cases through the use of cathodic protections combined with suitable dielectric coating.

The key to a successful pipeline or rebar anti-corrosion program is the coating system. There are also advanced polymers, which help with the battle against corrosion.

According to Michael Osborne, President and CEO of Nukote Coating Systems International, "polymer products are 'Thickfilm coatings', which are very different from traditional paints or coatings. Traditional paints and coatings are Thinfilm products that are applied in multiple layers to achieve reasonable thicknesses. Our polymer coatings are 'Monolithic' or non-layered at any desired thickness and are extremely durable, resistant to impact, erosion, sunlight, abrasion and chemicals providing superior resistance and longer protection to the end user."

How are pipelines checked:

* Video Inspection Technology

* Umbilical Operated Ultrasonic Tools.(UT)
* Magnetic Flux Leakage (MFL) Technology
* Pipeline Emergency Repair for external corrosion by Clock Spring
* Pipeline External Inspection for detecting of internal and external metal loss using SLOFEC (Saturated Low Frequency Eddy Current) Technology.

* Tank Floor Inspection using Saturated Low Frequency Eddy Current (SLOFEC) Technology.

* Pipeline Specialized Internal Cleaning using high pressure water systems or/ and purpose made hydro mechanical cleaning PIGS.
* Risk Based Inspection.
* Rope Access Based (Abseiling) inspection for hard to reach locations.
* Cathodic Protection Ranging from pre-feasibility to final commissioning.
* Closed Circuit Television (CCTV) Inspection.

 

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