Segregation and Separation
Pipeline and Hazardous Materials Safety Administration · May 22, 1995 · Reference No. 95-0243
Interprets: 49 CFR § 177.848
Reggie’s quick take
Someone asked whether steel cylinders and ton containers holding hazardous materials can also serve as the non-permeable barriers that keep incompatible cargo apart under § 177.848(e)(3). The agency said no. A packaging's integrity cannot count as the physical barrier, because if the packaging failed, the materials could mix. The containers themselves do not meet the separation rule, so a separate barrier is still needed.
Written by AI (Claude) on Oct 22, 2026. Robots make mistakes and leave things out, so the letter below is what counts. Not legal advice.
This is in response to your letter concerning the segregation and separation requirements of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Specifically, you ask whether steel cylinders and ton containers containing hazardous materials may serve as both packagings and non-permeable barriers to satisfy the separation requirements in 49 CFR 177.848(e)(3). I apologize for the delay in responding and hope it has not caused any inconvenience.
In accordance with § 177.848(e)(3), separation must be accomplished by some means of physical separation, such as non-permeable barriers, non-reactive freight, or non-combustible, non-reactive adsorbents between packagings of hazardous materials required to be separated. The mere integrity of a packaging may not be used as a physical barrier. If the packaging should fail, commingling of materials could not be prevented. Therefore, the mere packaging itself may not be used to satisfy the requirements of § 177.848(e)(3).
A letter of interpretation applies the regulations to the facts the requester described. It isn’t a regulation and isn’t legal advice. The agency’s copy.