L-127 RS-RDX Round Robin Preliminary Results Analysis

April 2006
Ruth Doherty, NSWC-IHD, USA Lori Nock, NSWC-IHD, USADuncan Watt (Energetic Materials)

In connection with NATO Committee AC/326 Sub-Group I on Energetic Materials, the USA has accepted a task to revise STANAG 4022 (Edition 3) "Specification for RDX (Hexogene) for deliveries from one NATO nation to another". This was promulgated in 1983 but contains requirements and test methods unchanged from earlier decades. In practice, STANAG 4022 was found to have limited use with some nations, notably the USA and UK, preferring to use their own national standards. In the revised Edition 4, the USA custodian has proposed to introduce some test requirements from MIL-DTL-398D namely HMX content by HPLC, impact sensitivity test and granulation requirements by wet sieving method. This is expected to broaden the applicability of the document for procurement purposes.

The question arose as to whether STANAG 4022 would cover the requirements for a grade of RDX that had been demonstrated to give reduced shock sensitivity in cast PBX compositions. This grade of RDX, produced by the French company SNPE and called i-RDX? has a crystal quality unique to its method of manufacture but otherwise meets the STANAG or MIL specification. Other manufacturers are beginning to offer equivalent products. The STANAG does not contain any test requirement that will enable such products to be differentiated from "normal" RDX such as that manufactured by Ordnance Systems Inc at the Holston Plant.

A technical meeting on Reduced Sensitivity RDX was held in Meppen, Germany on 17-20 November 2003 under the authority of AC/326 Sub-Group I and assisted by NIMIC(MSIAC). An objective was to consider possible techniques to allow discrimination of the normal and insensitive grades.

An outcome of the meeting was a recommendation that a Round-Robin inter-laboratory study should be conducted to examine a suitable test method or methods to distinguish the reduced sensitivity form of RDX and also to perform analyses to validate the acceptance criteria in the draft edition 4 of STANAG 4022. The tests proposed to be carried out in the RS-RDX Round-Robin (R4) are listed therein. The methods for the tests were distributed to all R4 participants, the methods are detailed in MSIAC report L-114 and STANAG 4022-Ed 4 Draft.