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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Interpretation Response #PI-76-035

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

Interpretation Response Details

Response Publish Date:

Company Name:

Individual Name:

Country: US

View the Interpretation Document

Response text:

July 8, 1976

Publication of Document in the Federal Register
Certifying Officer, Office of Pipeline Safety Operations, MTP-30
Office of the Federal Register

Attached is the original and two copies of a document to be published in the Federal Register
entitled, Corrosion Control Deadline.

Please do not make any changes without calling me, 118-62392.

Margaret E. Hammond




PIPELINE SAFETY - DOT/MTB explains corrosion control requirements.


Materials Transportation Bureau


Corrosion Control Section

On June 25, 1971, the Department of Transportation issued safety standards for the
protection of metallic gas pipelines from external, internal, and atmospheric corrosion. The
standards are contained in 49 CFR Part 192, Subpart I, and apply to operators of pipelines used in
the transportation of gas in or affecting interstate or foreign commerce. Because operators
needed time to prepare for protecting existing pipelines, certain provisions were incorporated in
Subpart I to allow adequate lead time for operators to comply with the new standards. For
example, Section 192.457(b) provides a 5-year lead time with respect to certain pipelines (except
for cast or ductile iron) installed before August 1, 1971.

This notice serves as an aid to operators in meeting the August 1, 1976, deadline for
compliance in Section 192.457(b) by explaining applicable requirements. It also states the policy
of the Office of Pipeline Safety Operations (OPSO) with respect to enforcement of the standards.

Section 192.457(b) reads as follows:

(b) Except for cast iron or ductile iron, each of the following buried or submerged
pipelines installed before August 1, 1971, must, not later than August 1, 1976, be
cathodically protected in accordance with this subpart in areas in which active corrosion is

(1) Bare or ineffectively coated transmission lines.

(2) Bare or coated pipes at compressor, regulator, and measuring stations.

(3) Bare or coated distribution lines. The operator shall determine the areas of active corrosion by electrical survey, or where electrical survey is impractical, by
the study of corrosion and leak history records, by leak detection survey, or by other means.

Section 192.457(c) defines the term "active corrosion:"

(c) For the purpose of this subpart, active corrosion means continuing corrosion which, unless controlled, could result in a condition that is detrimental to public safety.

In response to problems and questions concerning the corrosion control requirements, a number of interpretations have been published in several monthly Advisory Bulletins. The
following questions and answers, some of which have been previously published but are now restated for clarity, provide significant interpretations with regard to corrosion control under
Section 192.457(b).

1. Question: Which methods of "electrical survey" may be used to comply with the requirements of 49 CFR 192.457(b)?

OPSO Interpretation: Under Section 192.457(b), an operator must use an electrical survey method which identifies all areas of continuing corrosion along a pipeline with
enough detail so that the operator can determine whether a condition detrimental to public safety could result. This public safety determination is necessarily based, among other
relevant factors, on the effect of any continuing corrosion on a pipeline. Therefore, to meet the requirements, an electrical survey method must provide accurate measurements,
by direct or indirect techniques, of corrosion rate, loss of metal relative to pipe wall thickness, potential differences, and current flow, which are factors necessary to evaluate
the effect of corrosion. There are many electrical survey methods that an operator can use to meet the requirements, but OPSO does not preferentially recommend one method over

2. Question: May leak surveys or corrosion leak records be used as a substitute method for determining areas of active corrosion under Part 192?

OPSO Interpretation: Under Section 192.457(b) an operator must determine the areas of active corrosion by electrical survey, except that where electrical survey is impractical, the
study of corrosion and leak history records, leak detection surveys, or other means may be used to determine active corrosion areas. Thus, leak surveys or corrosion leak records
may be substituted only in those instances where determination by electrical survey is impractical.

3. Question: When is an electrical survey impractical?

OPSO Interpretation: The phrase "where electrical survey is impractical" is used in
subpart I to identify those instances or situations where, through no fault or shortcoming
of the operator, it is unreasonable or inappropriate to perform an electrical survey due to
the extreme hardship, trouble, or expense involved in the survey.

4. Question: What areas of a pipeline must be cathodically protected under Section

OPSO Interpretation: Section 192.457(b) requires that a pipeline be cathodically
protected in areas in which "active corrosion" is found. The term "active corrosion" is
defined as "continuing corrosion which, unless controlled, could result in a condition that
is detrimental to public safety." Determining where cathodic protection is required by
Section 192.457(b) is a two step process. First, an operator must find areas of active
corrosion by electrical survey or other allowable methods. If active corrosion that is not
detrimental to public safety can be demonstrated, cathodic protection is not required.

Secondly, where active corrosion is found, the operator must determine whether a
condition detrimental to public safety could result therefrom, taking into account the short
and long range effect of the localized corrosion on the pipeline, the pipeline's proximity to people, and all other factors relevant
to public safety. If after consideration of all relevant factors, it can reasonably be
concluded that a condition detrimental to public safety does not exist now or in the
foreseeable future, localized cathodic protection is not required. If a pipeline remains
unprotected, Section 192.465(e) requires that it be reevaluated every three years for the
existence of "active corrosion."

Question: Is a pipeline which is located so that the bottom portion is buried and the top
portion extends above the ground level subject to the cathodic protection requirements?

OPSO Interpretation: The same cathodic protection requirements applicable to a fully
buried pipeline apply to a partially buried pipeline because electrochemical process which
causes corrosion on underground pipelines are equally active with respect to a partially
buried pipeline.

Question: How often must a pipeline that is cathodically protected only in areas of active
corrosion be monitored under Section 192.465?

OPSO Interpretation: Such a pipeline may be divided into protected and unprotected
sections. Section 192.465(a) requires that the protected sections must be tested at least
once each calendar year, but with intervals not exceeding 15 months, to determine
whether the cathodic protection meets the requirements of Section 192.463. However,
Section 192.465(a) further provides that if tests at those intervals are impractical for
separately protected service lines and short sections of protected mains, not in excess
of 100 feet, these service lines and mains may be surveyed on a sampling basis as set
forth in the section. (Note: The emphasized section [bolded], above, was originally
marked to be omitted because it was felt the answer was not responsive to the question.)
Section 192.465(e) requires that at intervals not exceeding 3 years, unprotected sections
must be reevaluated and cathodically protected in areas in which active corrosion is found.


In accordance with Section 9 of the Natural Gas Pipeline Safety Act of 1968 (49 USC
1678), any operator not under the jurisdiction of a certified State agency who violates the
requirements of Section 192.457(b) shall be subject to a civil penalty of not more than $1,000 for
each such violation for each day of the violation, except that the maximum penalty may not
exceed $200,000 for any related series of violations. In determining the amount of such civil
penalty and its appropriateness, OPSO will evaluate an operator's efforts towards compliance
during the 5 years between August 1, 1971 and August 1, 1976.

This evaluation includes the operator's corrosion control plan, past accomplishments, projected completion dates, and all
relevant extenuating circumstances. If a civil penalty is considered appropriate, Section 9 of the
Act further provides that in determining the amount of that penalty, or the amount to be agreed
upon in compromise, the following factors are to be considered:

1. The appropriateness of the penalty to the size of the business of the person charged.

2. the gravity of the violation, and

3. the good faith of the person charged in attempting to achieve compliance after notification of a violation.

In addition to civil penalties, Section 10 of the Act provides for appropriate injunctive
sanctions in the case of a violation of a safety standard.
Operators under the jurisdiction of a certified State agency are subject to substantially the
same enforcement policy as operators under the direct enforcement jurisdiction of OPSO. This
similarity is required by Section 5(a) of the Act in that each certified State agency must enforce
the safety standards under a State law with "injunctive and monetary sanctions substantially the
same as are provided under Sections 9 and 10."


Section 3(b) of the Act provides that the Secretary of Transportation or a State agency
participating under Section 5 of the Act may grant a waiver from compliance with any gas
pipeline safety standard. A waiver is necessary if a person proposes to operate a pipeline facility
in a manner that varies from applicable standard, so that the operation will not violate the safety
standard and subject the person to a civil penalty or injunctive sanction.

Waivers are intended only for those situations where a general safety standard is not
appropriate for a particular situation or condition. A waiver is granted only after there has been a
convincing demonstration of cogent reasons why a given standard should not be followed or an
alternative safety measure is more appropriate. Waivers ar not intended for those situations
where a violation exists and the administering government agency defers imposition of a penalty
or other sanction while an operator executes a plan of compliance. Both OPSO and State agency
compliance efforts include this discretionary action.

(Sec. 3, Pub. L. 90-481, 82 Stat 721 (49 USC 1672); 40 FR 43901, 49 CFR 1.53).

Issued in Washington, D.C. on ____________________
Cesar DeLeon
Acting Director
Office of Pipeline
Safety Operations

Regulation Sections

Section Subject
192.457 External corrosion control: Buried or submerged pipelines installed before August 1, 1971