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

Interpretation Response #02-0290 ([Raymond Schaffer])

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

Interpretation Response Details

Response Publish Date:

Company Name:

Individual Name: Raymond Schaffer

Location State: CA Country: US

View the Interpretation Document

Response text:

JUL 30, 2003

Mr. Raymond Schaffer                                         Ref. No. 02-0290
4477 Sheila Street
Los Angeles, CA 90023

Dear Mr. Schaffer:

This is in response to your August 26, 2002 letter concerning the requirements for a turntable assembly on a DOT Specification cargo tank motor vehicle under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Specifically, you ask if the turntable assembly, as depicted in the photographs you provided, must be removed to fulfill either the visual inspection or pressure test required by § 180A07(d)(2)(viii) and (g)(1)(iii), respectively.

Turntable assemblies serve the same function as an upper coupler and must be removed from the cargo tank for inspection in accordance with § 180A07(d)(2)(viii) and (g)(1)(iii), respectively. The primary purpose for this inspection is to inspect for corroded and/or abraded areas of the cargo tank which may require thickness testing. Upper couplers are normally attached to the tank using bolts and are designed to be removed and replaced, if necessary. Turntables are typically attached to the tank by means of welding and are not designed to be removed from the cargo tank without cutting. Turntable assemblies serve as the front support for the trailer in lieu of dolly legs and they normally stay attached to the cargo tank for the life of the tank, very similar to the rear suspension components of the cargo tank.

From the photographs you provided it does not appear that the turntable can be removed from the tank without cutting and welding. Further, removing the turntable would not facilitate a more thorough external visual inspection of the area of the cargo tank directly above the turntable. Therefore, the turntable assembly may remain on the cargo tank under the following conditions:

  1. The turntable assembly must allow a complete external visual inspection of the area of the cargo tank that is directly above the turntable. The visual inspection must be as effective as performing an external visual inspection of this area if the turntable were to be removed.
  2. The external visual inspection and pressure test must be conducted by directly viewing the tank; therefore, the use of a device that creates an image of the tank (i.e., mirrors, cameras, or fiber optics) is prohibited.
  3. All major appurtenances and structural attachments on the cargo tank that can be inspected without dismantling the turntable assembly must be inspected for any corrosion or damage that might prevent safe operation (§ 180A07( d)(2)(viii)).
  4. Areas covered by the turntable assembly must be inspected for corroded and abraded areas, dents, distortions, defects in welds, and any other condition that may render the cargo tank unsafe for transportation service (§ 180A07(g)(1)(iii)).

If the area above the turntable cannot be observed and the turntable cannot be removed without cutting and welding then the tank must be internally inspected and those areas of the tank above the turntable must be thickness tested in accordance with § 180A07(i)(2). The number of thickness test points is dependent upon the area of the tank shell above the turntable that cannot be visually inspected. For each square foot of tank shell surface area above the turntable you must perform six thickness tests. A copy of the thickness test report identifying the areas tested and the measurements recorded for each test location must be maintained with the external visual inspection report or the pressure test report, as appropriate, and a copy of this report must be provided to the owner and operator, if not the owner, of the cargo tank.

The photographs you provided indicate that this cargo tank and turntable assembly could fulfill the criteria outlined above. However, if the cargo tank is not equipped with a manhole, the turntable assembly must be removed from the cargo tank in order to meet the visual inspection and/or pressure test requirements.


Susan Gorsky
Senior Transportation Regulations Specialist
Office of Hazardous Materials Standards

Regulation Sections

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