Ingenieurwissenschaften und zugeordnete Tätigkeiten
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A joint Round Robin test was initiated by the "explosives testing user group" involving all renowned test institutions of the USA plus The Netherlands (TNO) and Germany (BAM). Aim of the Round Robin test was not only to align results with regard to the friction sensitivity of a given powder sample, but also to study the variations of GO and NO-GO reactions by high speed camera recordings.
This presentation shall outline the regulatory tools for explosives manufacture in force in Germany and emphasize the benefits of a codified approach. Those in the need of applying safety measures find a given set of prescriptions, which do not need to be determined through a case by case study. While a process hazard analysis is usually required, it is not necessary to perform a risk analysis.
The system is likely to be more conservative than others, because it generalizes the application cases and needs to be valid for all variations within the description. It is also conservative in that respect that, from learning from previous accidents, for each case a conclusion improving safety entered the code. The more recent history of events shows that the system provides excellent protection of workers in this field. In addition it gives all operators a safe backup for their activity, since following the code generates the "presumption of conformity" and makes juridical judgement more straight forward.
Controlling the hazards in explosives manufacture has been addressed ever since such substances have entered industrial processing. The rigour of exercising such control appears to vary in different fields of application (fireworks versus blasting explosives) and in different countries worldwide. Nonetheless, each tradition has developed a set of standard tests addressing sensitivity and other aspects of behaviour of explosives. With a full system of workers protection in place in most countries nowadays, the control of hazards in explosives manufacture has become much more formalised. The paper aims to show the common parts of process hazard analysis and the consequential steps involving either a risk based approach or a prescriptive approach. The paper aims to stimulate discussions about recent developments.
Examinations of the mechanical properties of the BAM drop hammer and the BAM friction test were done recently. In order to validate the correct functioning of both tests, usually Round-Robin tests are done with selected test substances. A relatively large spread of the results including some outliers is usually accepted and attributed to the nature of the tests. The author asked, however, in how much the mere mechanical properties could already differ between different institutes, even when no substance is involved (dry runs). A thorough inter-laboratory study was done for the drop test, and results for the friction test are on its way. The current state of these investigations will be presented.
Shock tube systems are non-electric explosive fuses employed in blasting and demolition applications to trigger the detonation of explosive charges. Their working principle is based on the explosive reaction of a fine explosive powder on the tubing's inner surface, generating a shock wave traveling at a velocity of 2,100 m/s along the length of the tube, without destroying it. One of
the key aspects of the manufacturing process of these shock tubes is the size and morphology of the explosive powder grains and their distribution on the inner wall of the tube, in order to propagate the shockwave efficiently and reliably. For the first time, synchrotron X-ray computed tomography has been used to characterize non-destructively the explosive powder grains, typically Al/HMX between 10 and 20 μm in size, in terms of morphology and 3D distribution but also to characterise the presence and location of defects
within the shock tube walls.