The manufacture of DOT Specification 4L cylinders

January 09, 2020

Reference No. 19-0102

This letter is in response to your July 31, 2019, letter requesting clarification of the Hazardous Mater
ials Regulations (HMR; 49 CFR Parts 171-180) applicable to the manufacture of DOT Specification 4L
cylinders. You seek confirmation of your understanding that the phrase “same condition” as used i
n § 178.57(j)(1) means the sheet or plate material has received all plate processing operations—incl
uding heat treatment—as the material used to form the heads and the cylinder. Specifically, you ask
k whether tensile test samples may be taken from the flat plate that will be used to form the heads or
or cylinder, or whether the samples must be taken from the head or cylinder after forming.

Tensile samples must be taken from either the head or cylinder after it has been formed. In accord
ance with § 178.57(j)(1), “the test is required on 2 specimens selected from the material of each he
at and in the same condition as that in the completed cylinder.” In other words, a sample from the flat pla
flat plate that will be used to form the head or the cylinder would not be in its completed form or in the cond
the condition of a completed cylinder. Therefore, the test sample must be taken from either the head or th
ad or the cylinder once the cylinder has been formed.

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

Sincerely,

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

178.57(j)(1)