Saturday, April 12, 2008

Tom Hamilton comments.

I was trained as a metallurgical engineer. My first exposure to corrosion was in a course taught by Henry Van Droffelaar and Jim Atkinson. The notes from that undergraduate corrosion course were published and distributed by NACE in book form, “Corrosion and its Control”. I continued post-graduate studies in corrosion with Dr. Atkinson.
My transmission pipeline career began at TransCanada PipeLines. While I was there, we sponsored the development of the first instrumentation to allow instant-off pipe to soil readings on our close interval surveys. In that era, we also hired the best consultants in our business, including Bob Gummow, Tom Barlo and John Dabkowski, to extend our knowledge of the CP arts.
I was an early believer in using instant off surveys to limit the unpleasant effects of IR drop on our P/S readings. This technique was the principal method we used in the ‘80’s to account for IR drops in our field measurements. At first I found it interesting (confusing) that previously in the lab, we had not used interrupted readings when we recorded data. It was explained to me that this was because in the lab we were typically using conductive electrolytes, placing the tip of our Luggin capillary very close to the specimen surface, and limiting the IR drop in our measurement circuit to virtually zero using electronics. That made sense.
I thought I had a pretty good understanding of CP criteria and pipe to soil measurements. At TransCanada we had hosted two sites for the PRCI research that Dr. Barlo had led. The 100mV criterion made sense to me. Current interruption made sense to me, as I had measured huge errors in measurements that I had made over the years on many miles of CIPS that I had done, and on thousands of miles of pipe that I had taken care of. I learned my fieldcraft from Robin Pawson. I knew well the errors that can corrupt a P/S reading due to poor survey technique. Unbalanced or otherwise poorly maintained half cells. Poor half cell contact that can overwhelm even meters with high input impedance. The price of selecting a very very high input impedance for your survey. Lots of things that take time effort and experience for new practitioners to learn. It sure helps to have good mentors around for guidance!

So how did I end up on this side of the fence in the present debate? Curiously, I initially threw in with the “850 On” crowd because of my libertarian political leanings. You see, a couple of years ago, I worked on the revision of RP 0502, a practice that I had worked with for some years. We techies were interested in making revisions to that document since it had proven itself to be overly conservative in places, and we knew we could improve on it by applying various lessons learned during the five years of implementation. We were going to add value to the RP based on the results of our surveys, and on the many excavations we had performed. Science was going to be advanced, and our Companies were going to receive value due to our changing of these overly conservative requirements.
I was shocked when our committee was shut down. It seems that science was not to advance that day. It was made very clear to us that if we made any movement in a non-conservative direction, that the credibility of NACE might be undermined, since the DOT might decide that they did not like our changes, and could simply refuse to acknowledge our revised version in their regulations!

The same phenomenon seems to be at work today, on yet another NACE committee. Both science and empirical data are being undermined by political process. You see, it is much easier for the DOT (or PHMSA) to “persuade” our committees to change our recommended practices than it is for them to field large numbers of qualified auditors. I am very aware of this phenomenon. I have compliance auditors reporting to me. We much prefer to audit hard numbers rather than trying to audit thoughts or whims. I know that. It is impossible to audit someone’s intentions. Or their motivations. It is only possible to audit their work output versus agreed-upon requirements. Their adherence to written policy and procedures.

I know that it is difficult to audit a Company’s “consideration” of IR drop. Difficult, but not impossible. And that gets my dander up. Why should our Recommended Practices be modified into something that they were not intended to be, just to satisfy the Regulators? Why are the legitimate technical positions and opinions of the founding members of this association being ignored and marginalized? Why do the critics not have to prove the inadequacy of the criterion before they throw it out?

It is assumed that we have a criterion problem. I’ve not seen that in my 29 years of practice. My embarrassing leaks have always been due to inadequate CP, not inadequate criteria. It’s the practice of engineering that has failed me, not the theory of engineering principles.

I for one will continue to throw my support behind the movement to restore the original 850 On criterion, as stated in the original version of RP 0169.

And by the way, the more I look into the science behind the 850 On criterion, the more I think we’d better pause and confirm once and for all its technical applicability. I’ve not seen anything yet that leads me to believe we’d better throw it out…So I’m also going to support the movement to more fully understand the science behind the 850 On criterion.

Perhaps you’ll join us?

These comments are provided by Tom Hamilton and are his comments and experiences, not those of his company.