We know that your company’s president, John Muncaster, states pretty strongly that the pipeline industry is allowing a lot of unnecessary corrosion through its use of corrosion coatings that block protective cathodic protection (CP) currents. What are your thoughts on the cathodic shielding problem?
Richard Norsworthy. Pipeline operators across the world work hard to provide a safe and reliable mode of transportation for oil, gas and their derivatives. Overall they have done a good job of protecting these assets, the surrounding communities and the environment. But there is room for improvement. One area is developing a better understanding of how pipeline coatings work with cathodic protection.
Most of the external corrosion problems we have today are caused from past and continued use of pipeline corrosion coatings that shield cathodic protection current. If a corrosion coating literally breaks away and leaves a visible open area on the pipe surface, there is no shielding, because nothing blocks the protective currents. But if the coating loses adhesion and separates from the steel in a blister-like or tunnel-like configuration, the steel is now exposed to water. The corrosion process will now begin if the corrosion coating shields the cathodic protection current. Unless the protective current can penetrate the top of the blister (as it does with fusion bond epoxy coatings) or underneath the lap of the coating (as it does with Polyguard's RD-6 coating) the current usually cannot protect most of the exposed steel surface.
You've personally taken a controversial industry stance by acting, in the words of one industry member, as "the leader of the rebel alliance" in coordinating opposition to a proposed update to the NACE SP0169-2007 standard. Could you tell us about that?
RN. In the first place, our opposition has little to do with the cathodic shielding concern discussed above. The existing SP0169 language is already fairly specific about shielding and is in line with our views.
Also, you really have to be technically knowledgeable in the cathodic protection field to understand this debate, so I won't even try to explain the finer details of the controversy. From a big picture point of view, however, you have two groups of industry experts at odds here, arguing whether CP standards should change to be more stringent.
On the 'change' side, you have a group of experts who believe that more complex CP measurements and calculations need to be performed by pipeline operators on their systems. These experts, primarily CP service providers, regulators and researchers, believe that adequate CP protection is not provided using the present criteria. Their conviction, from what I can see, comes from their professional concern backed up by a limited amount of field and laboratory studies.
On the 'let it be' side, you have the pipeline operators and a smaller group of experts. This group maintains that the present CP criteria have a 60-year track record of success, and that the type of problems that concern the 'change' people are isolated. Moreover, the 'let it be' side is really concerned about the level of new investment that pipeline operators will be required to make to expand their CP if the proposed changes are implemented. An engineer from one large multi-state gas utility told me that his company estimates over $100 million in investment will be required, and higher day-to-day operating costs will be needed as well.
So this is serious stuff; it's a very large potential investment and you don't feel it is necessary?
RN. That's absolutely right. As a matter of fact, I feel that our industry is in great shape if only we would do the smart things. The industry has really good coatings technology, if we focus on just the non-shielding coatings. Fusion bond epoxies now have an almost 50-year track record. Corrosion is almost never found on FBE coated lines, except when there is AC or DC interference, which is a completely separate issue. And Polyguard's non-shielding product, RD6 wrap, has a 21-year track record without a single case of corrosion occurring.
CP technology is also well developed. It is a mature technology that is highly effective - except, of course, when used on lines with corrosion coatings that shield. Tools and methods for finding corrosion before it causes leaks and other problems are improving rapidly and impressively. The bottom line is that the industry has almost everything it needs today.
Polyguard has sponsored a blog so that the industry has an open forum on this debate. Please visit www.SP0169.com for further details.
Richard Norsworthy is Director, Lone Star Corrosion Services, Polyguard Products Inc. of Ennis, Texas.