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Interpretation Response #03-0241 ([Metropolitan Water District of Southern California] [Ms. Carol Kaufman])

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

Interpretation Response Details

Response Publish Date:

Company Name: Metropolitan Water District of Southern California

Individual Name: Ms. Carol Kaufman

Location State: CA Country: US

View the Interpretation Document

Response text:

Jan 30, 2004


Ms. Carol Kaufman               Reference No. 03-0241
Senior Environmental Specialist
Metropolitan Water District of
Southern California
Los Angeles, California 90012

Dear Ms. Kaufman:

This responds to your inquiry regarding the requirements for inspection and testing of MC-331 cargo tanks containing chlorine under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180).  This is a follow-up to your telephone conversation with Phil Olson of our Office of Hazardous Materials Technology regarding required inspection and testing requirements for DOT specification MC 331 cargo tank motor vehicles (CTMVs) as they relate to amendments adopted in a final rule published on April 18, 2003 [Docket HM-213, effective October 1, 2003].

You state that the Metropolitan Water District of Southern California (MWD), a public water provider, uses DOT specification MC 331 CTMVs in chlorine service.  Annually, in accordance with § 1 80.407, the MWD conducts a partial, visual external inspection of the steel cargo tank (insulation prevents a complete visual external inspection) and records the results in inspection reports.  A visual internal inspection is not conducted concurrently, as every two years the cargo tanks are subjected to hydrostatic pressure testing and leakage tests.  You ask if the annual, partial visual external inspection of an insulated MC 331 cargo tank used in chlorine service, combined with pressure and leakage testing every two years, complies with the requirements at §180.407(d).

Section 180.407 of the HMR contains the requalification requirements for DOT specification CTMVs.  Paragraph (c) of this section includes a table that establishes test and inspection intervals for different types of CTMVs.  Paragraphs (d) through (i) of this section describe how each required test and inspection must be performed.  Section 180.407 must be read in its entirety in order to ascertain which tests and inspections are required for a specific CTMV.

On April 18, 2003, the Research and Special Programs Administration published a final rule [68 FR 19258; Docket HM-213; effective October 1, 2003] adopting a number of revisions to the HMR to update and clarify the regulations on the construction and maintenance of CTMVs.  Paragraph (d)(1) of §180.407 was revised to provide the correct references for hydrostatic and pneumatic testing of cargo tanks, where a visual inspection is precluded because the cargo tank is lined, coated, insulated or designed so as to, prevent access for external or internal inspection.

Paragraph (d) of § 180.407 sets forth requirements for the performance of an external visual inspection.  Paragraph (d)(1) generally requires an internal visual inspection in accordance with paragraph (e) of § 180.407 in place of the external visual inspection where insulation precludes performance of the external visual inspection.  The table in § 180.407(c) is consistent with paragraph (d)(1); in accordance with the table, insulated cargo tanks are required to have an internal visual inspection every year.  Note, however, that MC 331 CTMVs are excepted from this requirement.  Instead, MC 331 CTMVs are required to have an internal visual inspection every five years.

You are correct that under the HMR, as amended by the HM-213 final rule, you need not perform an annual internal visual inspection of your insulated MC 331 CTMVS in place of the annual external visual inspection.  An annual, partial visual external inspection, combined with pressure and leakage testing performed every two years in accordance with paragraphs (c), (g), and (h) of § 180.407, satisfies the test and inspection requirements applicable to MC 331 CTMVs in chlorine service.  We note that this test and inspection regimen includes an internal visual inspection as part of the pressure test.  Taken together, the test and inspection procedures utilized by MWD assures frequent evaluation of the integrity of the cargo tank while minimizing atmospheric exposure that could accelerate corrosion (which could be a potential consequence of an annual visual internal inspection).

I hope this information is helpful.  If can be of further assistance, please contact us.



Edward T. Mazzullo
Director, Office of Hazardous Materials Standards


Regulation Sections

Section Subject
180.407 Requirements for test and inspection of specification cargo tanks