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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 #19-0025

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: Robbie Dunn

Location State: MN Country: US

View the Interpretation Document

Response text:

September 12, 2019

Robbie Dunn, P.E.
Westmor Industries, LLC
3 Development Drive
Morris, MN  56267

Reference No. 19-0025

Dear Mr. Dunn:

This letter is in response to your March 4, 2019, email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the transportation of propane in a Specification MC331 cargo tank motor vehicle (bobtail). You describe a scenario where for propane deliveries made to customers, the driver must back into unfamiliar locations to complete the delivery and there are safety implications due to limited visibility and blind spots. As such, you are considering mounting a reel to the front of the bobtail chassis, which during transportation, will contain a residue of less than 10 gallons of propane in the piping and hose. Furthermore, you state that due to chassis variations or lack of chassis structure at the front of the bobtail chassis, you want to avoid installing a protection device.

You ask whether your configuration of piping, the internal valve, a secondary valve, and shear section is enough isolation from the cargo tank to consider the approximate 10 gallons of residual propane in the reel and piping to be independent from the bulk package (e.g., separate packaging).

The answer is no. Although the hose and piping used for loading and unloading a Specification MC 331 cargo tank is subject to the packaging specification, the hose and piping are not authorized to contain hazardous materials during transport. The propane in the hose and piping must be removed to the fullest extent practicable upon completion of loading or unloading the cargo tank.

Furthermore, although there is no restriction against mounting the hose reel and piping to the front of the MC 331 chassis, in accordance with § 178.337-10(a), all valves, fittings, pressure relief devices, and other accessories to the cargo tank must be protected against damage caused by collision with other vehicles or objects. Moreover, in accordance with § 178.337-10(f)(2), each internal self-closing stop valve, excess flow valve, and check valve must be protected by a shear section or other sacrificial device and the sacrificial device must be located in the piping system outboard of the stop valve and within the accident damage protection device to prevent any accidental loss of lading.  Based on the information and attachments provided, your design would not meet the accident damage protection requirements prescribed in § 178.337-10.

I hope this information is helpful. Please contact us if we can be of further assistance.


Dirk Der Kinderen
Chief, Standards Development Branch
Standards and Rulemaking Division

178.337-10, 178.337-10(a), 178.337-10(f)(2)

Regulation Sections

Section Subject
178.337-10 Accident damage protection