Comments to the TG 360 committee

Comments to the TG 360 committee:

As the struggle continues to revise this document we must work together and respect each persons experience, knowledge and education. Each of us has formed different opinions of what we think should be in the document. Since the main problem is with the CP criteria, I will focus on that today.

Norm Moriber has an article in May addition of Materials Performance that discusses some of the issues surrounding the revision of the SP0169. I do agree with Norm on many of the topics he has discussed in this article. First, I know that the committee and many other NACE members have worked very hard to resolve these problems. There have been some significant changes in the last revision that updates many of the references. Significant information has been added about pipeline coatings and mechanical damage protection (rock shields, etc.). I personally think they have too many references that confuse the coating tables, etc.

Most of the concern is with the fact that the document no longer has a separate criterion that states the use of an “ON” -850 mV or more negative potential as a viable option. The word “consider” is the word that is at issue with the committee in the 2007 and earlier versions. “Consider” can be defined in different ways and this seems to be the road block.

Yet the committee still uses “consideration” throughout the most recent document. Here are a few areas where “consideration” is still used in last revision:

6.2.3.1.3 Criteria that have been shown to successfully control corrosion through empirical
evidence on specific piping systems may continue to be used on those piping systems or others
with the same characteristics. These criteria include –850 mV on with consideration for
voltage drops other than those across the structure-to-electrolyte boundary, other current applied
criteria, net current flow, 300 mV shift, or E log I.

6.2.3.2 Special Conditions
6.2.3.2.1 The amount of cathodic polarization maintained on a metallic surface may be affected
by changes in electrolyte conditions, CP system or structure configuration changes, and changes
in influencing sources of AC or DC currents. These factors should be considered when tests are
performed to verify compliance with the CP criteria.

6.2.3.2.5 In uniformly high-resistivity well-drained soil, instant-off potentials less negative than
–850 mV CSE may be sufficient. Note: ISO 15589-1 offers the following for consideration:
–750 mV where soil resistivity is between 10,000 Ω.cm and 100,000 Ω.cm, and –650 mV where soil resistivity is greater than 100,000 Ωm.

6.3 Other Considerations

It is interesting that most on the committee does not think we should use “consider” or its derivatives, yet the committee has chosen to use it several times in Section 6! In 6.2.3.1.3 it is used similar to the use in SP0169 – 2007 version. Why can we not just use it in the criteria section as in the 2007 version and move on?

I and others think that if the committee would simply leave the 6.2.2.1.1 as written in the 2007 version, the document would pass (with some cleaning up and elimination of so much extra stuff). Here is the wording in the 2007 version:

6.2.2.1.1 A negative (cathodic) potential of at least 850 mV with the CP applied. This potential is measured with respect to a saturated copper/copper sulfate reference electrode contacting the electrolyte. Voltage drops other than those across the structure to-electrolyte boundary must be considered for valid interpretation of this voltage measurement.

NOTE: Consideration is understood to mean the application of sound engineering practice in determining the significance of voltage drops by methods such as:

6.2.2.1.1.1 Measuring or calculating the voltage drop(s);
6.2.2.1.1.2 Reviewing the historical performance of the CP system;
6.2.2.1.1.3 Evaluating the physical and electrical characteristics of the pipe and its environment; and
6.2.2.1.1.4 Determining whether or not there is physical evidence of corrosion.

In this version the document has provided some guidance in to what they mean by “consider” which most folks can interpret without a problem. The way a company interprets “consider” should be clearly spelled out in each company’s procedure manual. It is their responsibility. The SP0169 is a standard to guide them, not dictate to them.

The referenced article mentions the potential of the STG 35 committee recommending the withdrawal of the SP0169 from NACE Standard Practices. This would be a great miss-justice to the membership of NACE. This was the first recommended practice NACE every published. We are the experts! Some on the committee would prefer this since most companies would then resort to the ISO standard for CP, which would give them what they want. For those of you who do not understand the ISO process, these documents are not voted on by members as in NACE. These are decided by a committee of folks from various countries that are given direction by those in that discipline, therefore not everyone has an opportunity to vote or even voice an opinion in all cases.

Whether this is a scare tactic by some on the committee or not, I am not sure, but it seems there are some who think these tactics will result in members voting for the standard whether it is correct or not just to be sure we keep the SP0169 in NACE.

We, the voting pool, the committee and NACE membership, must work together to complete this document in a manner that gives us the best document for the world’s corrosion control industry. As we move forward with this critical document, as with all NACE Standards, there must be compromise on both sides of the controversy.

I am asking the committee to please consider the keeping the 6.2.2.1.1 as stated in the SP0169-2007. This would likely resolve the issue and allow the document to move forward. Since the committee has used the term “consideration and considered” in basically the same manner in the last attempted revision, there is no reason not to use it again. This is a compromise that we should all be able to live with!

As Norm points out, PLEASE VOTE if you are on the balloting list. Also, do not vote for or against any NACE document without studying, questioning and understanding the various parts as much as possible before making your decision. Never feel intimidated by those in the industry that “know” more than you. Each person has a different level of expertise and knowledge. Yours is as valuable in the process as everyone else’s. Ask for help and clarification when needed. This is the way we all learn and helps us to produce the best SP0169 document ever published!

Any comments are welcome to the blog site. Even Norm’s! I will be fair and print all suggestions to the committee that are constructive comments and information. This is not a forum to bash anyone, but is one to allow free expression and ideas, especially for those who feel intimidated in front of the committee.

I want to thank every one who has supported the SP0169.com blog site. Polyguard Products, Inc. has allowed me time and provided the resources to support this process. Please let me or some one at Polyguard know if there is any way we can help you with any pipeline coating or corrosion control issues. Please visit our website at polyguardproducts.com.

Thank you,

Richard Norsworthy
NACE Corrosion Specialist # 4037