• All rules that change the HMR are issued by PHMSA in a process involving multiple rounds of notifications, comments, and revisions.

The Pipeline and Hazardous Materials Safety Administration (PHMSA) issues all rules that change the Hazardous Materials Regulations (HMR).

PHMSA often issues an Advanced Notice of Proposed Rulemaking (ANPRM) that discusses suggested changes and requests comments on the possible options.

If the changes are not very complicated, or after comments from an ANPRM have been reviewed, a Notice of Proposed Rulemaking (NPRM) is issued. The NPRM has the exact wording and changes as they could appear in a final rule. Comments on the proposed changes are requested.

After comments on an NPRM are reviewed, a final rule is issued. This contains the changes to the regulations. The changes may become effective on the date of publication or at a date specified in the rulemaking. The date when the changes become effective is when the regulations actually change. Compliance with the changes may be mandatory on the effective date, or it could be delayed, in some cases for several years.

Even after the final rule is issued, comments can still be submitted, and appropriate changes may be made by PHMSA. If these changes are made, they will be issued in another final rule.