Interpretation Response #01-0122
Below is the interpretation response detail and a list of regulations sections applicable to this response.
Interpretation Response Details
October 15, 2001
Mr. Alan F. Campbell Reference No. 01-0122
2400 Aluminum Avenue
Hampton, Virginia 23661
Dear Mr. Campbell:
This is in response to your May 8, 2001 letter concerning the heat treatment requirements in 49
CFR 178.46 (f) and (j) for cylinders made to the DOT 3AL specification. Your questions are
paraphrase and answered as follows:
Ql. What constitutes a heat treatment under §178.46(f)?
Al. Under § 178.46 (f), a heat treatment consists of two parts, a solution heat treatment
conducted at a high temperature to dissolve the alloying constituents, followed by an aging treatment (artificial or natural) to allow the alloying constituents to precipitate. The aging treatment may involve more than one heating cycle (artificial aging) in order to achieve the desired material properties.
Q2. Are additional aging treatments considered reheat treatment under § 178.46(j)?
A2. No. The aging treatment alone is not considered reheat treatment. The reheat treatment
described in § 178.46(j) begins only when the cylinder is subjected to a second solution
I hope this information is helpful.
John A. Gale
Transportation Regulations Specialist
Office of Hazardous Materials Standards
|§ 178.46||Specification 3AL seamless aluminum cylinders|