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Interpretation Response #PI-76-026 ([American Society of Mechanical Engineers' (ASME)] [George L. Mocharko])

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date:

Company Name: American Society of Mechanical Engineers' (ASME)

Individual Name: George L. Mocharko

Country: US

View the Interpretation Document

Response text:

May 25, 1976

Chief, Technical Division
Chief, Regulations Division
George L. Mocharko
American Society of Mechanical Engineers' (ASME)

Request to Revise Section 192.465

ASME has requested that the Office of Pipeline Safety Operations (OPSO) revise 49 CFR Section
192.465 by including the following as an alternate method for monitoring cathodically protected

"Where electrical test methods for evaluating and monitoring are impractical or are
ineffectual in applying the criteria for cathodic protection in Appendix D of this Sub-Part;
annual leakage surveys, and, corrosion and leak history studies, may be used to verify and
monitor the effectiveness of cathodic protection and other corrosion control procedures."


Corrosion accounts for the largest number of repaired leaks each year. The minimum
Federal safety regulations contained in Subpart I wee promulgated and became effective as
of August 1, 1971, to provide the highest degree of protection for the public from leak
incidents attributed or caused by corrosion. In that corrosion is the largest single problem
which is controllable, within the operators capacity, from a technical feasibility and
economic practicability standpoint; it would be an anomaly to revise Section 192.465 as
stated by ASME. If safe operations is the goal as set by OPSO, corrosive control
measures must be instituted before leaks occur. Monitoring is the only means by which
the operator can prevent a hazard which can become detrimental to public safety.

Technical Summary:

  1. Cathodic protection is an electrical method of preventing corrosion on metallic
    structures (such as pipelines in electrolytes) and involves electro-chemistry. Therefore, it
    is illogical to monitor or verify whether or not cathodic protection has been installed to
    prevent corrosion or is at adequate levels to control corrosion with annual leakage
    surveys, and corrosion and leak history studies.
  2. There has been no systematic attempt to develop direct results or corrolation [sic]
    between gas leakage or leaks to cathodic protection or severity of corrosion, hence,
    electrical surveys, measurements, and tests are the only acceptable technology for
    monitoring or verification. It appears operators would like to just conduct post mortem
    leak surveys rather than any preventative surveys. This is supported by the contract
    studies OPSO had initiated, such as Technical report No. OPS-TR-71-001, "Ferrous
    Pipeline Corrosion Processes, Detection and Mitigation," and Contract DOT-OS-40190,"Study on Current Practices, Technologies Problems, and Recommendations Relating to
    Overall Safety of Gas Pipeline Distribution Systems," and NTSB accident reports. The
    TR-71-001 report stated, "At this time the best indicator of pipeline corrosion appears to
    be close monitoring and interpreting of pipe potentials. Since it is current leaving the
    buried structure that causes corrosion, the optimum measurement would be the
    determination of current leaving the structure." The DOT-40190 study stated, "Corrosion
    accounts for the largest number of repaired leaks each year. Improvements are needed in
    the overall understanding of the corrosion process and methods for better determination of
    active corrosion and assessment of applied cathodic protection. The methods now used
    by gas utilities to determine the physical condition and integrity of their pipelines are
    largely based on detecting and locating leaks. This procedure is essentially after the fact
    and largely precludes preventative maintenance. Efforts should be promoted to develop
    methods for identifying and locating deteriorating conditions before failure occurs and
    leakage ensues."


  1. The ASME has not provided adequate supportive information to justify the statement
    that electrical surveys are ineffectual and impractical for determining the adequacy of
    cathodic protection in distribution system. In fact, they have only summarized the
    variables that knowledgeable corrosion control persons have worked with for many years.

    They have also strengthened the position that OPSO has taken in the requirements of
    Section 192.453. "Each operator shall establish procedures to implement the requirements
    of this Subpart. These procedures, including those for the design, installation, operation
    and maintenance of cathodic protection, must be carried out by, or under the direction of,
    a person qualified by experience and training in pipeline corrosion control methods."
  2. The proposed ASME revision is not technically sound and would have the effect of
    shielding imprudent operators for liability to the public as well as penalize the prudent
    operators who have met the monitoring requirements of Section 192.465. However,
    OPSO should consider some sort of relief for the distribution or transmission operators
    with regard to conducting electrical surveys. OPSO should take a serious look at the time
    requirements of all surveys in the Federal standards to determine priority of performance
    to enhance safety.
  3. Surveys--One area of particular concern to the operators involves the monitoring of"hot spot" cathodic protection in active corrosion areas. More Information is needed to
    determine whether or not using a statistical sampling - probability approach as a method
    of monitoring or some other type of risk analysis be used to monitor the effectiveness of
    cathodic protection.


George L. Mocharko

Regulation Sections

Section Subject
192.453 General