Alert 14-10: A Manufacturer’s “M” Number or Symbol

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The Pipeline and Hazardous Materials Safety Administration (PHMSA) issues a symbol or “M number” to an industrial packaging manufacturing entity as a means of identification. Under certain provisions of Title 49 of the Code of Federal Regulations (CFR), the M number must be used as the sole identifier on a package. However, other regulations allow the manufacturer to use either the symbol or their name and address, as specified in 49 CFR §178.3 (a)(2).

On its website, PHMSA provides lists of manufacturer M numbers or symbols in two formats. The first lists the manufacturers sequentially by identification number (M number), while the second lists each state’s manufacturers alphabetically by city and company name. The M number, name and address, status, and date of the registration are provided in both formats.

How do you apply for an M number or symbol?

All approval applications can be submitted, using the online application, by email to [email protected] or by mail to Department of Transportation, East Building, PHH-33, 1200 New Jersey Avenue SE, Washington, DC 20590. The M number or symbol registration request should contain the following:

  • A request letter, as described in 49 CFR §107.705, must be sent to the Approvals Office.
  • The request letter must contain detailed information on the purpose of the M number or symbol and the item that will be marked with the M number.
  • Provide the name, facility and mailing address, email (optional), and telephone number of the person on whose behalf the registration or application is made and, if different, of the person filing.
  • If the company seeking registration is an international location, they must provide a U.S. agent name, company and contact information attached to their request.


Who can use your M number?

Recently, PHMSA issued interpretation 11-0259  regarding the use of M numbers by subcontractors. The interpretation states that a company cannot use an M number assigned to another company. In accordance with §178.503(a)(8), if a subcontractor manufactures your company’s packagings, they must mark the packaging with their name and address, if permitted for the particular type of packaging, or they must mark the packaging with an M number issued to them.


Issued 01/14

This information is based on the Industrial Steel Drum Institute’s best knowledge at time of issuance. It is the responsibility of any filler or user of steel drums and pails to ensure that the unique characteristics of products contained therein or any reformulation of products are accurately described to the drum and lining manufacturers. Customers, fillers and users should consult the appropriate professional for assistance in compliance with the responsibilities outlined hereunder.