Interpretation Response #22-0021

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

Interpretation Response Details

Response Publish Date: 01/24/2023

Company Name: Matson Navigation Company

Individual Name: Mr. James Owen

Location State: AZ Country: US

View the Interpretation Document

Response text:

January 24, 2023

Mr. James Owen
Dangerous Goods Specialist
Safety, Quality, Environment, and Security
Matson Navigation Company
426 North 44th Street, Suite 250
Phoenix, AZ 85008

Reference Nos. 22-0021 & 22-0061

Dear Mr. Owen:

This letter is in response to your March 25, 2022, and June 8, 2022, correspondence requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to polymeric beads transported in cargo transport units in accordance with § 176.907.

We have paraphrased and answered your questions as follows:

Q1. You ask whether your understanding is correct that an explosion-proof refrigerated cargo transport unit is not required when transporting polymeric beads, provided the requirements pertaining to cargo transport units in § 176.907(b) are met.

A1. Your understanding is correct. The requirement that a cargo transport unit be "explosion-proof" is required under § 176.907(a) for any mechanical devices used for ventilation and does not apply to refrigerating equipment used to comply with the alternative provisions in § 176.907(b).¹

¹ Please note that polymeric beads will release volatile hydrocarbons during storage and transportation. The rate of release increases with temperature. In enclosed spaces and under warmer temperatures during normal conditions of transportation, polymeric beads may release a flammable concentration of gas, necessitating the safety controls in paragraph (a) to ensure proper ventilation and to prevent mechanical devices, such as an electric fan, from being a source of ignition. Refrigerated cargo transport units, however, are not subject to the ventilation or explosion-proof requirements for mechanical devices as the cooler temperatures provided by the refrigeration unit suppress the release of volatile hydrocarbons.

Q2. In your letter, you reference the requirement in § 176.907(d) for marking and stowage of polymeric beads. You ask whether a refrigerated cargo transport unit used to satisfy the requirements in § 176.907(b) must be "powered off" prior to unloading to be clear of any source of ignition as specified in § 176.907(d)(2).

A2. If—as a result of being powered on—the refrigerated cargo transport unit is a source of ignition, then it must be powered off prior to performing loading and unloading operations. The refrigerated cargo transport unit should be powered on as soon as practicable once loading operations are complete.

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

Sincerely,

T. Glenn Foster
Chief, Regulatory Review and Reinvention Branch
Standards and Rulemaking Division

176.907, 176.907(a), 176.907(b), 176.907(d), 176.907(d)(2)

Regulation Sections