24.0856 Corrosion control-External.

Cite as [A.S.A.C. § 24.0856]

(a) Buried or submerged pipelines.

(1) Except as provided in paragraphs (2) and (3) of this subsection, each buried or submerged pipeline must be protected against external corrosion using appropriate corrosion control methods, including the following:

(A) It must have an external protective coating meeting the requirements of subsection (c) of this section;

(B) It must have a cathodic protection system designed to protect the pipeline in accordance with subsection (d) of this section, installed and placed in operation within 1 year after completion of construction;

(C) It must not contain aluminum if that aluminum is exposed to a natural environment with a Ph in excess of 8.0.

(2) An operator need not comply with paragraph (1) of this subsection if both of the following requirements are met:

(A) The operator can demonstrate by tests, investigation, or experience in the area of application, including, at a minimum, soil resistivity measurements and tests for corrosion accelerating bacteria, that a corrosive environment does not exist. However, within 6 months of an installation not in compliance with paragraph (1) the operator shall conduct tests, including pipe-to-soil potential measurements with respect to either a continuous reference electrode or an electrode using close spacing, not to exceed 20 feet, and soil resistivity measurements at potential profile peak locations, to adequately evaluate the potential profile along the entire pipeline. If the tests made indicate that a corrosive condition exists, the pipeline must be cathodically protected in accordance with paragraph (1).

(B) The operator can demonstrate by tests, investigation, or experience that, for a copper pipeline, a corrosive environment does not exist, and for a temporary pipeline having an operating period of less than five years, that any corrosion which may occur will not be detrimental to public safety.

(3) This subsection does not apply to electrically isolated, metal alloy fittings in plastic pipelines, if:

(A) for the size of the fitting to be used the operator can show by test, investigation, or experience in the area of application that adequate corrosion control is provided by the alloy composition; and

(B) the fitting is designed to prevent leakage caused by localized corrosion pitting.

(c) Examination of buried and exposed pipeline. Whenever an operator has knowledge that any portion of a buried pipeline is exposed, the exposed portion must be examined for evidence of external corrosion if the coating is deteriorated. If external corrosion is found, remedial action must be taken to the extent required by the rules adopted under 24.0859.

(d) Protective coating.

(1) Each external protective coating, whether conductive or insulating, applied for the purpose of external corrosion control must:

(A) Be applied on a properly prepared surface;

(B) Have sufficient adhesion to the metal surface to effectively resist underfilm migration of moisture;

(C) Be sufficiently ductile to resist cracking;

(D) Have sufficient strength to resist damage due to handling and soil stress; and

(E) Have properties compatible with any supplemental cathodic protection.

(2) Each external protective coating which is an electrically insulating type must also have low moisture absorption and high electrical resistance.

(3) Each external protective coating must be inspected just prior to lowering the pipe into the ditch and backfilling, and any damage detrimental to effective corrosion control must be repaired.

(4) If coated pipe is installed by boring, driving, or other similar method, precautions must be taken to minimize damage to the coating during installation.

(e) Cathodic protection.

(1) Each cathodic protection system required by this subpart must provide a level of cathodic protection that complies with one or more of the applicable criteria contained in Appendix D of 49 CFR 192 Subpart I, which is hereby incorporated by reference. If none of these criteria is applicable, the cathodic protection system must provide a level of cathodic protection at least equal to that provided by compliance with one or more of these criteria.

(2) If amphoteric metals are included in a buried or submerged pipeline containing a metal of different anodic potential, then:

(A) The amphoteric metals must be electrically isolated from the remainder of the pipeline and cathodically protected; or

(B) The entire buried or submerged pipeline must be cathodically protected at a cathodic potential that meets the requirements of appendix D of 49 CFR 192 Subpart I.

(3) The amount of cathodic protection must be controlled so as not to damage the protective coating or the pipe.

(f) Monitoring.

(1) Each pipeline that is under cathodic protection 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 this section.

(2) Each cathodic protection rectifier or other impressed current power source must be inspected six times each calendar year, but with intervals not exceeding 2 and ½ months, to insure that it is operating properly.

(3) Each reverse current switch, each diode, and each interference bond whose failure would jeopardize structure protection must be electronically checked at least once each calendar year, but with intervals not exceeding 15 months.

(4) Each operator shall take prompt remedial action to correct any deficiencies indicated by the monitoring.

(5) After the initial evaluation required by subsections (a)(2) and (a)(3) of this section, each operator shall, at intervals not exceeding 3 years, reevaluate its unprotected pipelines in which active corrosion is found. 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.

(g) Electrical isolation.

(1) Each buried or submerged pipeline must be electrically isolated from other underground metallic structures, unless the pipeline and the other structures are electrically interconnected and cathodically protected as a single unit.

(2) One or more insulating devices must be installed where electrical isolation of a portion of a pipeline is necessary to facilitate the application of corrosion control.

(3) Except for unprotected copper inserted in ferrous pipe, each pipeline must be electrically isolated from metallic casings that are part of the underground system. However, if isolation is not achieved because it is impractical, other measure must be taken to minimize corrosion of the pipeline inside the casing.

(4) Inspection and electrical tests must be made to assure that electrical isolation is adequate.

(5) An insulating device may not be installed in an area where a combustible atmosphere is anticipated unless precautions are taken to prevent arcing.

(6) Where a pipeline is located in close proximity to electrical transmission tower footings, ground cables or counterpoise, or in other areas where fault currents or unusual risks of lightning may be anticipated, it must be provided with protection against damage due to fault currents or lightning, and protective measures must also be taken at insulating devices.

(h) Testing. External corrosion control test stations and test leads shall be established and maintained in accordance with the provisions of 49 CFR 192.469 and 192.471, which are hereby incorporated by reference.

History: Rule 02-01, eff 30 Aug 01.