L-052 Discussion on the IM and Hazard Class Test Methods

February 1999
Jason deW FitzGerald-Smith (Warhead Design)

During the NATO IM Experts Working Party (IM EWP) meeting of AC/310 Sub-Group IV in September 1998, it was agreed to hold a joint meeting with NATO Group AC/258 on how the requirements for Hazard Class (HC) testing and IM testing might be combined. This latter group is responsible for the Safety Aspects of Transportation and Storage of Military Ammunition and Explosives, and as such has to base its safety conditions on the results of UN Hazard Classification testing. It is generally understood that the tests to fulfill the needs of IM assessment and Hazard Classification are very similar, but the testing assumptions and the testing requirements are very different. In the past this has caused difficulties in reaching a commonality in the testing because HC testing is based on UN legislation.

To help both the IM and Hazard Classification communities resolve these differences in testing and perhaps prepare a way ahead for future discussions for a common test approach, NIMIC conducted a comparison exercise of the current IM and HC test methods for the specific stimuli of Fast Heating, Sympathetic Reaction, Bullet Impact and Slow Heating. The purpose of the exercise was to identify common requirements in the two testing approaches and against these requirements highlight the key differences that are apparent in Tables 1 to 4. As a result, 9 major test requirements were identified in which there were s distinct differences, and these cover the following:

  • the test parameters;
  • the medium for conducting the test;
  • the configuration of the article for the test;
  • the test conditions;
  • the number of items or articles for each test;
  • the number of tests required;
  • the amount of instrumentation;
  • any acceptance criteria

Also included in these comparison tables are Test Procedures that were generated by representatives of the hazard classification and safety community at the 2 NIMIC Workshops on IM Testing in 1997. These test procedures were based on the existing IM test STANAGS, but redrafted to show how the IM testing could become both more explicit and standardized. It should be noted, that a major decision of the participants to these NIMIC Workshops was that these proposed test procedures should be written more in a form of guidance. They should concentrate on what should be done in the test, rather than how the test should be conducted. It was considered that this latter issue should be left to the discretion of the test engineer in his test plan.