Wednesday, June 4, 2008


When we look at all the reasons proposed for the changes to the SP0169-2007 (RP0169) one consideration that must be involved in the discussion is the cost to implement the proposed criteria changes. Though some say cost should not be considered in providing the industry with a Standard Practice, it must be considered when companies are asked to spend a considerable amount of money, with little or no improvement to the integrity of their systems.

There are many other changes that are needed, but I believe there are few needed to the Section 6 that is the main topic of discussion. Some of those changes are discussed in the other Blog topics.

In this section I would like to discuss the cost of implementing and maintaining some of the proposed changes to the criteria section. When I have asked some of the experts about how do companies that use galvanic anodes that have no access (or even if they do) prove a polarized potential or 100 mV of polarization, they say the companies can install coupons to confirm these two criterion.

There are many inherent problems with coupons and their design. Some of the issues with coupons include, but are not limited to:

1. Where is the coupon placed in relationship to the structure? (How close what position around the pipe, etc.)
2. What size should the coupons be? (They always say it should represent the size of the largest holiday in the area. Now how are we going to know that? If the pipe is bare?)
3. What shape should the coupon be? (Round, square, rectangular, etc.)
4. Should the coupons be coated on one side?
5. What material should the coupon be made of?
6. Where should the reference cell be placed in relationship to the coupon? (Should it be in the tube above the coupon with native soil, special backfill, or no backfill? Should it just be placed on the ground above the soil?)
7. Should the reference be Copper/Copper Sulfate or zinc?
8. Should you wet the soil in the tube before the potentials are taken?
9. Where should the reference cell be placed in relationship to coupon?
10. There are many different types of commercial coupon test stations, what are the differences?
11. Does the potential reading really represent the potential of the pipe?

Once you figure out what type of coupon to use and where to place it (etc.), then you have to pay for it, install it and maintain it. The coupon test stations with stationary reference cells, must concern themselves with how long the reference cell will be accurate, etc.

Below is one example of the cost of using these coupons on a large gas distribution/pipeline system in the southern USA.

“Richard, it would cost (Company name with held) in excess of $100,000,000 to install coupon test station on magnesium protected distribution CP Zones and in excess of $5,500,000 for additional impressed current on our transmission systems. There would also be an increase in labor and transportation to monitor the -850 "off". These are conservative numbers!”

These numbers can easily be multiplied by each company that has galvanic protected pipelines and may be forced to use coupons to prove their protection level. These numbers do not reflect the cost of maintaining and replacing as needed.

Another large gas distribution/pipeline company in the central northern USA provides similar information and opposes such changes. They do not see any need for IR drop consideration from their many years of using an “ON” -850 mV criterion with no CP related failures reported.

The following is extracted from a power point presentation and a letter to the TG 360 committee:

• Does not support revisions to Section 6 that would eliminate the -850 mV “On” criteria or requirement that reading needs to be corrected for IR drop.
• CP (corrosion) problems that we have identified are not caused by lack of CP, but rather by stray current, interference, or third party damage.
• Proposed changes in SPO 169 would probably require large effort to install coupon test stations and increase in CP output
• It is possible that large expenditures could be made that would result in no improvement in system integrity. It would be more prudent to direct resources to known issues.

“We have operated our system successfully using the -850 mV “On” criteria for the past 37 years and are experiencing declining leak rates on steel pipe. We have not had a reportable incident caused by a corrosion leak on protected steel pipe in many years. Operating our corrosion control program under the current standards in combination with a leak survey program has been very effective in maintaining system integrity. The proposed changes to SPO 169 could cause a significant increase in our operating expense with little or no benefit.

If these changes are adopted into DOT code, we would need to install coupon test stations to validate the IR drop measurement. It could potentially cost millions of dollars to install these test stations and increase CP output, and result in little or no improvement in system integrity.”

These are just two examples of companies that have a real problem with the potential cost of the proposed changes that may require installation of coupon test stations to prove the criteria is being met.

Transmission pipeline companies that use mostly impressed current CP will be required to do polarized potential surveys which once again means additional cost and effort. There has not been a decision made on how often these companies may have to do such surveys to satisfy the regulatory requirements of each country, state or local government. If these surveys have to be performed annually, this presents a real economic challenge.

With NACE International wanting to project a GREEN image, why do we want to propose such a drastic change in the cost of performing a CP survey to satisfy a criterion that will require significant effort, energy usage (the amount energy used can be 2 to 3 times more to achieve a polarized -850 mV versus an -850 mV ON {without IR drop considered} and up to 5 times more than using a 100 mV polarization change), more vehicles and equipment to do these more complicated surveys, potential for more interference leaks caused from more CP being used, as well as potential damage from hydrogen and further disbondment of coatings. This will not project a GREEN image.

Politically NACE is now tied to ANSI and ISO so they have to follow certain guidelines when changing standards. One problem that some have on this committee is that the fear if we do not make these changes, it will say that NACE is not progressive in providing change to improve these documents. Since ISO, other organizations and some countries require more stringent criteria, they are of the belief NACE must follow because these organizations must know what they are doing and if we want to be the leader in corrosion control, we must change to be more stringent! I have no problem with change when it is needed and proven to be needed, but just to change because some else does makes no sense to me.

2 + 2 equals 4 in most parts of the world and it works. What if a certain group decides that it should be 7? Does everyone automatically without reservation change to seven because a few experts decide it is better because one of them wrote a paper about it or someone in a particular country is doing it?

NACE should be and I think is the leader in the corrosion community because we have consensus documents, not one formatted by some select committee that knows more than any one else or can afford to go to the meetings. I think progress also includes correcting mistakes made by former committees. For example, when we were forced to consider IR drop in the -850 mV criterion back in 1992 (I think), this was a mistake that has led some to believe that it is the same as the polarized potential so why not just have the one polarized -850 mV criterion. This was a compromised change in order to get the document out the door. Some will know what I am talking about. This was wrong then and is now. Change it back to “IR should be considered” when unusual circumstances require it.

The cost to the world wide industry will be tremendous with little or no improvement. There are certainly times when more stringent criterion is needed, but it should be forced on every situation, because it works in some unusual environment.

I challenge those who are in favor of the proposed changes to provide us with the significant documentation that proves the changes are needed so we can all review and comment. I also challenge those who believe as I do that we need to go back to a reasonable criterion that allows us to use the -850 mV ON with consideration for IR drop only when unusual circumstances require it to get your information together. The industry has over 50 years of data that can be used to prove much of what we are saying, but it is typically ignored in favor of some scientific papers that many times did not prove the point in most folk’s minds.

By the way, I am still waiting for someone to prove me wrong about the use of FBE coating and the fact that we do not have significant, if any, external corrosion problems even though most have used the -850 mV “ON” without consideration for IR drop (at least the first 30 + years of FBE usage). There have been disbondments, adhesion failures and blistering of FBE since the beginning, yet unlike most coatings there are not the shielding problems. So why do we not have external corrosion if we must have a polarized -850 mV? This is an important issue and the industry must use the data from the ILI pig data and ECDA data to prove this to the committee.

If you have not done so please read the other postings. Go to the Polyguard website at and read articles about why we still have external corrosion on pipelines (because of coatings that shield CP when they fail) that are cathodically protected.

Please send comments and we will post them. We need everyone’s input to keep this problem in front of the cathodic protection industry around the world. Thanks for your help and please let me know if I can help you with pipeline coatings or CP questions, etc.

Richard Norsworthy
Polyguard Products, Inc.