Shrapnel Mitigation Methods for Linear Shape Charges

The purpose of this paper is to investigate commonly used methods for mitigating the effects of shrapnel from linear shape charges (LSC) used in the demolition industry. Primarily the problem is not that shrapnel poses a threat to human bystanders, but rather it can affect the other charges in the demolition or damage to structures in close proximity to the charges. This research aims to determine what methods have success at stopping shrapnel, what methods do not, and to promote an awareness of the dangers of using the LSC without any protection. The project was carried out at the Experimental Mine site at the Missouri University of Science and Technology. This research is an undergraduate research project to fulfill the requirements for the Explosives Engineering minor program at MST. The test parameters for the project are as follows: a four inch (100 mm) length of LSC of varying core load, initiated with an electric cap and 8-gram booster, cutting a length of steel. The charge was placed in a steel drum and various methods of “catching” the shrapnel surrounding the LSC were tested. The purpose of the drum was that of a witness material, the inside painted for each test to see if any shrapnel escaped the protective material and damaged the drum. Initially there were three different materials tested as protective material: sandbags, conveyor belt, and water bags. The tests started with 600-grain LSC and moved up in charge density. The water bags were the first to be tested. The conveyor belt showed promise and deserves more testing outside the scope of what we can do since we had limited access to varying materials with respect to thickness and reinforcing material. The sandbags outlasted the initial testing and were able to move on to further testing. Here the scope of the project changed to what thickness of sandbag was required to stop the shrapnel for a given charge density. Finally, testing with a standoff between the charge and the sand was performed. The project has determined, at this point, with the materials tested, that sandbags are the most reliable method of stopping the shrapnel from a LSC. Of course there may be other materials out there that operators have found successful. A side benefit of the project was that we have developed a method of testing that is easy to replicate and inexpensive to construct. This type of testing would be highly beneficial for any demolition contractor to do to ensure that the measures they are taking for protection are worthwhile