USA Banner

Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

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

Interpretation Response #04-0226 ([Beau Transport Equipment Co] [Mr. Marvin M. Miller])

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

Interpretation Response Details

Response Publish Date:

Company Name: Beau Transport Equipment Co

Individual Name: Mr. Marvin M. Miller

Location State: OR Country: US

View the Interpretation Document

Response text:

Dec 23, 2004


Mr. Marvin M. Miller                 Reference No.: 04-0226
Operations Manager
Service Department
Beau Transport Equipment Co.
8801 North Vancouver Avenue
Portland, OR 97217

Dear Mr. Miller:

This responds to your September 30, 2004 letter requesting clarification of the requirements in the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to periodic testing and inspection of specification cargo tanks. In particular, you are concerned about the requirements in § 180.407(d) applicable to insulated cargo tanks and specifically § 180.407(d)(4) applicable to external ring stiffeners installed on insulated cargo tanks.

Section 180.407(c) requires all specification cargo tanks to have an external visual inspection at least once each year. Where insulation precludes an external inspection, MC 330, 331, and 338 cargo tanks may be given either an internal visual inspection in conjunction with the external visual inspection or a hydrostatic or pneumatic pressure-test (see the chart entitled Compliance Dates — Inspections and Test Under § 180.407(c)). Insulated cargo tanks that are lined, coated, or designed so that access to the interior of the tank is not possible must be pressure tested in accordance with § 1 80.407(g)(1 )(iv) at the applicable time interval provided in § 180.407(c) (see § 1 80.407(d)( 1)). In instances where insulation precludes a complete external visual examination of the tank shell, a visual external inspection of a cargo tank’s piping, valves, gaskets, manholes, emergency devices, remote closures, and all major appurtenances and structural attachments must be conducted in accordance with § 180.407(d)(2) and included in the test report.

In accordance with § 180.407(d)(4), for cargo tanks constructed of mild steel or high- strength, low -alloy steel, external ring stiffeners and other appurtenances that create air cavities adjacent to the tank shell that do not allow for an external visual inspection of the tank shell must be thickness tested in four symmetrically distributed locations at least once every two years. This provision applies to both insulated and non-insulated tanks. On insulated tanks where the insulation may preclude the thickness test, you may need to remove the insulation jacket surrounding the ring stiffeners in order to comply with this requirement. You should also note that the exception provided in § 180.407(d)(1) authorizing alternate means to comply with the provisions contained in paragraphs (d)(2) thru (d)(6) of § 180.407 does not apply to thickness testing of the ring stiffeners or other appurtenances.


I hope this information is helpful. Please contact us if you require additional assistance.



John A. Gale
Chief, Standards Development
Office of Hazardous Materials Standards


Regulation Sections

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