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Interpretation Response #PI-18-0008

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

Interpretation Response Details

Response Publish Date:

Company Name: IHI E&C International Corp.

Individual Name: Mr. Thomas Donaldson

Location State: TX Country: US

View the Interpretation Document

Response text:


Mr. Thomas Donaldson
Project Director,
Elba Liquefaction Project
IHI E&C International Corp.
1080 Eldridge Parkway
Suite 1300
Houston, TX 77077

Dear Mr. Donaldson:

In a March 7, 2018, letter to the Pipeline and Hazardous Materials Safety Administration (PHMSA), you requested an interpretation of 49 CFR Part 193. Specifically, you requested an interpretation about whether marking with die-stamping was permitted on a 24-inch diameter, stainless steel pipeline with nominal ¼-inch wall thickness (NPS 24, schedule 10S) that will be used as LNG vapor lines (i.e. lines 1218 and 1219) designed for -270°F and will operate at approximately -220°F. Though you did not cite to a specific section of Part 193 in your request, PHMSA notes that the marking requirement at issue is incorporated by reference in §§ 193.2013 and 193.2303. You also reference your January 2017 interpretation request regarding the applicability of § 192.63, Marking of Material, and National Fire Protection Associate (NFPA) 59A Section 6.3.5, Pipe Marking. PHMSA responded in an email on January 22, 2017 stating that die-stamping is permitted under certain circumstances under Part 192. However, the regulations for Part 192 do not apply to Part 193; therefore, that interpretation does not apply to your current request.

NFPA 59A (2001 ed. incorporated by reference, see §§ 193.2013, 2303) incorporates by reference American Society of Mechanical Engineers International (ASME) B31.3 (1996) which requires that pipes be marked. You stated that your position is that the provisions in Section 6.3.5 of NFPA 59A related to pipe marking are not applicable to this pipeline because Section 6.3 is "titled Installation, and as such is reasonably interpreted to apply to activities that occur post manufacture." You have already installed die-stamped pipe and stated that your pipe meets, in addition to the 2001 edition of NFPA 59A, all the applicable requirements of American Society for Testing and Materials (ASTM) A358, ASTM A999 and ASME B31.3.

Section 193.2301 states that "Each LNG facility constructed after March 31, 2000 must comply with requirements of this part and of NFPA-59A-2001... In the event of a conflict between this part and NFPA 59A, this part prevails." Under § 193.2303, construction acceptance, "no person may place in service any component until it passes all applicable inspections and tests prescribed by this subpart and NFPA-59A-2001..." NFPA 59A (2001), Chapter 6, Piping Systems and Components, Section 6.1.1, requires all piping systems to be in accordance with ASME B31.3, Process Piping (1996), and states that the additional provisions of Chapter 6 apply "to piping systems and components for flammable liquids and flammable gases with service temperatures below −20°F (−29°C)." The other standards referenced in your request, ASTM A358, ASTM A999 and ASME B31.3, have been incorporated by reference into NFPA-59A (2001), however, they do not address die-stamping.

Section 6.3.5 of NFPA 59A-2001 states:

6.3.5 Pipe Marking. Markings on pipe shall comply with the following:
(a) Markings shall be made with a material compatible with the basic material or with a round-bottom, low-stress die.

Exception: Materials less than ¼-inch (6.35 mm) in thickness shall not be die-stamped.

(b) Marking materials that are corrosive to the pipe material shall not be used. Under some conditions, marking materials containing carbon or heavy metals can cause corrosion of aluminum. Marking materials containing chloride or sulfur compounds cause corrosion of some stainless steels. Chalk, wax-base crayons, or marking inks with organic coloring shall be permitted to be used.

    Section 6.3.5 of the 2001 edition of NFPA 59A is applicable for pipe marking when the pipe is used for an LNG Facility under Part 193, which includes pipe manufacturing, installation during original construction or during operations or maintenance activities when the pipe used in piping systems and components for flammable fluids and flammable gases with service temperatures below -20º F. This provision states that when marking a pipeline, any pipe less than ¼-inch in wall thickness shall not be die-stamped for pipe used in piping systems and components for flammable fluids and flammable gases with service temperatures below -20º F. Die-stamped pipe of less than ¼-inch in thickness used in piping systems and components for flammable fluids and flammable gases with service temperatures below -20º F is therefore not permitted for use in LNG pipeline facilities subject to Part 193.

    You stated that "If Section 6.3.5 of the NFPA 59A were applicable to the project, it is your position that the reference to thickness refers to nominal thickness." Contrary to your statement that "NFPA has been known to specify actual thickness vs. nominal thickness," NFPA 59A (2001) does not reference "nominal thickness." The term “nominal thickness," therefore, does not apply to Section 6.3.5. Nominal wall thickness represents the defined thickness with a plus or minus allowable tolerance. While your pipe has a nominal wall thickness of ¼-inch, there is no guarantee that the actual wall thickness is ¼-inch. The pipe material may be "less than ¼-inch (6.35 mm) in thickness" and therefore die-stamping is not permitted.

    If we can be of further assistance, please contact Tewabe Asebe at 202-366-5523.


    John A. Gale
    Director, Office of Standards
    and Rulemaking

    Regulation Sections

    Section Subject