Interpretation Response #PI-82-017 ([Williams Pipe Line Company] [Keith E. Bailey])
Below is the interpretation response detail and a list of regulations sections applicable to this response.
Interpretation Response Details
Response Publish Date:
Company Name: Williams Pipe Line Company
Individual Name: Keith E. Bailey
Location State: OK Country: US
View the Interpretation Document
Response text:
Mr. Keith E. Bailey
President, Williams Pipe Line Company
P.O. Box 3448
Tulsa, OK 74101
Dear Mr. Bailey:
Your letter dated July 22, 1982, requesting an interpretation of §195.416, concerning a reduction in operating pressure as a remedy for isolated corrosion pitting.
The enclosed Pipeline Safety Regulatory Interpretation states that a reduction in operating pressure is an acceptable remedy for isolated corrosion pitting under §195.416(g).
Sincerely,
'signed'
Richard L. Beam
Associate Director for
Pipeline Safety Regulation
Materials Transportation Bureau
Enclosure
DEPARTMENT OF TRANSPORTATION
RESEARCH AND SPECIAL PROGRAMS ADMINISTRATION
MATERIALS TRANSPORTATION BUREAU
PIPELINE SAFETY REGULATORY INTERPRETATION
Note: A pipeline safety regulatory interpretation applies a particular rule to a particular set of facts and circumstances, and as such, may be relied upon only by those persons to whom the interpretation is specifically addressed.
SECTION: § §195.416(f) and (g)
SUBJECT: Isolated corrosion pitting.
FACTS: The Williams Pipe Line Company letter dated July 22, 1982, requested an interpretation of the requirements of § §195.416(f) and (g) concerning a reduction in operating pressure as a remedy for isolated corrosion pitting.
QUESTION: Is a reduction in operating pressure a permissible remedy for isolated corrosion pitting?
INTERP: Under §195.416, operators are required by paragraph (f) to replace, repair, or reduce the operating pressure on pipe that is found to be generally corroded. If isolated pitting of a particular size is found, paragraph (g) requires that the pipe be repaired or replaced. Under literal interpretation of paragraph (g), reduction in operating pressure would not be an allowable remedy for isolated corrosion pitting. Such a result would be illogical, however, since isolated pitting usually is a less serious hazard. Thus, it is reasonable that a remedy for general corrosion should also be allowed for isolated pitting.
The proposed rule and the preamble to the final rule for § §195.416(f) and (g) shed some light on the apparent inconsistency between paragraphs (f) and (g). These paragraphs were derived from a proposed §180.416(g)(33 FR 10213, July 17, 1968), which would have required that pipe found to be pitted so that the original wall thickness is reduced by 10 percent or more be replaced. In discussing the differences between the proposed and final rule, the preamble to the final §195.416 stated:
"As indicated in the discussion above on §195.114 with respect to used pipe, the important consideration in evaluating the usability of corroded pipe is the remaining wall thickness, and the requirements of paragraph (f) are reworded in this way. The carriers are also given the option of repairing the pipe in the case of small areas of corrosion. In addition, a new paragraph is added to provide for pitted areas. Under this paragraph, pitted areas need not be repaired or replaced if the pits are of small diameter and the wall thickness at the bottom of the pits is at least 70 percent of the nominal wall thickness."
This explanation of the changes suggests an intent to relax the relatively strict proposed rule by allowing the alternative remedies of repair and reduction in operating pressure, and by easing the threshold beyond which isolated pitting must be treated. In pointing out the significance of remaining wall thickness regarding the safety of corroded pipe, the preambulatory statement gives no indication that the corresponding remedy (reduction in pressure commensurate with wall thickness) should not be applied to isolated pitting. Indeed, reduction in pressure is an appropriate remedy for both types of corroded pipe (isolated and general), as indicated by the standards in §192.485 governing the remedial measures for corroded gas transmission lines. These standards specifically include pressure reduction as a remedy for isolated pitting.
The most reasonable reading of paragraphs (f) and (g) is, therefore, that reduction in operating pressure was intended as a remedy for corroded pipe, including isolated corrosion pitting, and §195.416(g) should be so applied despite the plain language of the rule.
A plausible explanation for the omission of this remedy in the language of paragraph (g) is that is would be very unlikely that operators would choose to bear the cost of reducing pressure solely to correct isolated pitting problems. Pressure reduction would only be cost effective for line sections that are generally corroded, although they may contain scattered instances of isolated pitting. In such cases, the isolated pitting may be viewed as part of the general corrosion, and §195.416(f) would apply rather than §195.416(g).
'signed'
Richard L. Beam
Associate Director for
Pipeline Safety Regulation
Materials Transportation Bureau