THE MAGAZINE

Explosive Testing of Window Systems – the Underlying Double-Standard

By Kenneth W. Herrle, P.E., and Larry M. Bryant, Ph.D.

Test Standards

Currently there are two independent test standards for explosive testing of window systems in the U.S. Both have their own specific markets:

  • U.S. General Services Administration (GSA) Test Standard (GSA-TS01-2003)
  • Used by the GSA and other non-Department of Defense (DoD) agencies who comply with the ISC Security Design Criteria
  • Available at no cost from the GSA (http://www.oca.gsa.gov/)
  •  ASTM Test Standard (ASTM 1642-04)
  • Widely used by some DoD components
  • Available for purchase from ASTM (http://www.astm.org/)

At this time, universally accepted blast test standards in the U.S. only exist for window systems.  Accepted blast test standards have yet to be developed for other façade elements such as doors and walls.

Test Standard Overview and Compliance – The Double Standard

Both the GSA and ASTM test standards were developed to ensure an adequate measure of standardization and quality assurance in the testing of window systems.  Each standard contains the following general provisions:

  • A listing of terms and definitions associated with the explosive testing of window systems
  • Performance Criteria/Hazard Ratings
  • A listing of test requirements, which include:
  1. Allowable test methods (shock tube or high-energy explosive arena testing)
  2. Blast load and explosive charge requirements
  3. Test site and reaction structure requirements
  4. Data collection and documentation requirements
  5. Test specimen requirements
  6. Test report requirements

With many similarities between the two, testing to either standard can typically be accommodated at the same test site through modifications of the test setup.  Unfortunately, with such similarities, distinctions between these two test standards have become increasingly blurred as test providers have slowly been intermixing differing components of each standard.  In addition, failure to include mandatory test requirements has become more commonplace.  Such behavior violates the protocol outlined in either test standard and has the potential for invalidating test results for unsuspecting test sponsors.

Fortunately, test sponsors can take precautions during pre-test planning to help protect the integrity of their test series.  The following recommendations can prove helpful in doing so.

For starters, the test sponsor should obtain a copy of the selected test standard prior to testing and become familiar with its requirements.  As part of the familiarization, distinction should be made between "test options" and "test requirements."  Test requirements are typically accentuated in the standards by phrasing such as “must,” “shall” and “as a minimum.” Each of these items must be accounted for in the tests, whereas test options do not.  For an explosive test to meet a selected test standard, all test requirements specified in the standard must be met.

The test sponsor should ensure that the test method being used meets the objectives of the test. For example, if the objective is to verify that the tested windows meet a specific GSA Performance Condition, it is unacceptable to perform the test using the ASTM Test Method. Conversely, if the test windows must meet a specific ASTM Hazard Rating, testing performed using the GSA Test Method is unacceptable.  In short, differing test methods and performance ratings cannot be intermixed; they are exclusive of one another. 

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