The recently adopted HM-215O includes a re-evaluation of certain explosives that were previously classified as 1.4S. For those that classify explosives, it is important to review this information and take appropriate action if your company is impacted.

The HM-215O Final Rule was issued on May 11, 2020 and has a delayed compliance date of May 10, 2021. PHMSA added special provision 347 to the following 1.4S explosive entries, which makes the UN 6(d) test (unconfined package test) applicable for the following UN numbers:

  • UN0349 Articles, explosives, n.o.s.
  • UN0367 Fuzes, detonating
  • UN0384 Components, explosive train, n.o.s.
  • UN0481 Substances, explosive, n.o.s.

Over 2,200 explosive approvals are impacted. Approval holders must ensure that the UN 6(d) test has been performed for these UN numbers. While not required, it is best that this information is included in the packing note on the approval to alert PHMSA and carriers to the holder’s compliance. If an approval already states that the UN 6(d) criteria was met, which labs may have done proactively starting in 2017, then no action is required. Otherwise, test results should be communicated to PHMSA no later than April 10, 2021. Optionally, a holder may retain their approval with no testing if they provide compatibility group information that can be used to reclassify the explosive as Division 1.4 other than compatibility group S.

“Alert” letters will be sent to every approval holder apprising them of this information, starting the week of October 5. PHMSA also plans to issue a Federal Register notice in January 2021 – a “Group Show Cause”- listing EX numbers which will be terminated if no information is received.

Please note: PHMSA may not find every applicable approval needing a notification, for example, those approvals containing multiple EX numbers on the same document.

For any actions other than termination, PHMSA is requiring an application for modification of approval under 49 CFR 107.709, including adding a note to an approval for which the UN 6(d) test was already performed. Holders who relinquish a 1.4S approval should consider informing your customers (i.e., re-shippers) that any packages they have may need to be remarked and relabeled and prepare shipping papers accordingly.

To fully explain the modification process, PHMSA has prepared a PPT that details the impact of the rule change as well as the process for approval modification. PHMSA PPT Click Here


Key Dates

  • Week of October 5, 2020 – PHMSA begins issuing “Alert Letters” to holders of approvals for the above-listed descriptions.
  • January 2021 – PHMSA to issue “Group Show Cause” Federal Register Notice informing public of the process and the expectation of termination for subject approvals that are not submitted for modification.
  • April 10, 2021 – PHMSA will begin the process of termination for approvals for which no information has been received to date as part of this re-evaluation process.
  • May 10, 2021 – Deadline for approvals to be modified. Existing approvals that have not been re-evaluated will begin to be terminated.


Q & A

  1. Why does this matter?
  2. Inaction could result in the inability to ship product at all or the risk of an enforcement action. Not passing the test could have impacts on transportation, e.g., only 1.4S explosives can ship as cargo on passenger aircraft, which may be the only way to reach remote destinations. Ocean shipping of 1.4 other than S is more difficult than for 1.4S.


  1. If my EX approval has a note showing that the UN 6(d) test has been performed, do I need to do anything?
  2. No.


  1. If I have not performed a UN 6(d) test and I want to keep my approval, what should I do?
  2. Contact an explosives lab and have the test performed. Then send the report to PHMSA with a cover letter containing the information required for an approval modification in 49 CFR 107.709. Holders are encouraged to do this early as lab schedules may fill up as the deadline approaches. If you think that your existing packaging may not pass the test, consult an expert first. A list of PHMSA authorized explosive test labs can be viewed from the PHMSA Website:


  1. If I have a foreign approval that is not from a PHMSA authorized explosive test lab but includes the UN 6(d) test, will that be accepted?
  2. PHMSA indicated they would consider foreign approvals if they include a report of the 6(d) test (see 49 CFR §173.56(f)). However, the test results must be submitted to PHMSA as part of an approval modification noted above.


  1. If I want to keep shipping, but don’t want to perform the UN 6(d) test or possibly augment the packaging to pass the test, what should I do?
  2. Submit a letter to PHMSA containing the information required for an approval modification in 49 CFR 107.709 to request an up-class to another Division 1.4 classification other than compatibility group S. Supply justification for your choice of compatibility group.


  1. My product is not approved as 1.4S. Am I affected?
  2. No.


  1. Will PHMSA automatically up-class my approval to 1.4 other than S if I don’t respond?
  2. No. Some of these UN numbers have multiple possibilities elsewhere in Division 1.4, and PHMSA cannot reassign them without your assistance and knowledge. They also need to follow the procedure for modification of an approval in 49 CFR 107.709.


  1. If the UN 6(d) test is applicable, does it absolutely have to be performed?
  2. No. A lab will have to provide a recommendation, but in lieu of testing they may analogize to another product that was tested, or they may demonstrate with other information that the product would pass the test so the test is not necessary. Waiving any required test is possible but this is subject to the discretion of the competent authority (PHMSA).


  1. Do I have to use the same lab as previous?
  2. No. Any lab may perform a new UN 6(d) test on a previously tested product.


  1. I am not an explosive or explosive article manufacturer but I may re-ship a part that is classified under one of the four (4) UN numbers listed. What should I do?
  2. Contact the part manufacturer to determine if the classification of the part will be affected. Also, you may view the EX approval at the PHMSA “Hazardous Materials Approvals Search Page” to ensure you are transporting the item utilizing the latest classification issued: