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Cutting detonating cord

W

weberoed

Well-Known Member
Ordnance approved
Now I have spent over a third of mu life in EOD, another (almost third) in the explosive community. I now have a small explosvies safety/engineering company whre I just take on jobs I want or if someone comes to me with enough money to "whore myself out". I just received a job where a small munitions company I do alot of work for, called about an OSHA inspection (in the US OSHA is our federal government safety enforcement agency). The company did OK except for one finding - OSHA sited them for cutting det cord with M2 crimpers. That the manufacture data sheet that is shipped withthe roll of detonating cord said not to use a shear or other cutting device, and that a razor or sharp knife should be used. "Oh no Mr Bill we're going to blow ourselfs up".

I've tried in past to address this problem, contacting as many commercial explosive firms as I could, from the US to Pakistan to South Africa. Each one of them agreed using M2 crimpers was not safe. So I contacted the US Dept of Defense Explosive safety group, they don't have a problem with using crimpers. Hell I've been cutting det cord with crimpers since I was 19 years old and I am considerably older now.

I have been asked to get this finding taken back, got an idea what I am going to o, but thought I'd throw this out there for comment

Mike
 
Mike, It turned black again on the second paragraph. I agree with you, though, I have NEVER had the det cord go off using the cutters on the M2 Crimpers, be they Sergeants, Dupont #4's, the Henley Filsons, the new crimpers with the back cutter, etc. There would be more likelihood of the cord going off by fiction from the sawing action of a razor knife than the shearing action of crimpers. Sounds like the inspector had to have at least one finding and that was it. Good luck, Bruce.
 
am trying to write up a reply now. I'll post it and OSHA reply later.

Still can't figure out why some of my posting go black, it's not like I cut and paste them.
 
I would like to see OSHA cite an instance were detonation / injury has ever occurred from cutting Det Cord with M2 Crimpers. Heck someone would be likely to seriously injure themselves using the required razor or sharp knife.
 
Back when I was a little more involved in such things, I toured a facility that had a variety of gov't. contracts for energetic "devices". They utilized a guillotine cutter for all their fuze and det cord cutting needs. Crafted of brass and used single edge razor blades. A slick little cam lever released the blade for quick change. The owner manufactured them himself and had a patent pending at the time. Not much of a demand for "sparkless guillotine cutters" so I'm guessing he didn't make his fortune with those.

Rick
 
Had the same conversation with people over visco fuse. The answer was ceramic sizzors available on evilbay for about 50 and they are sharp! Although i have never known, or know anyone who has also ever known, visco being ignited by cutters, it was a requirement as a risk assesment for an insurance company and is now the recognised safe way of cutting visco.
Hope it helps.
C.
By visco i include det cord, and time fuse as they are all the same thing ish.
example here
http://www.ebay.co.uk/itm/Kyocera-C...pt=UK_Kitchen_Accessories&hash=item4600185714
 
weli I've searched all the US data bases for explsoive accidents and there is no record of any det cord going off becasue of crimping. There is a web site outm of South Africa for commerical explsoives I contacted them and they even say crimpers are dangerous.

As for the guillotine cutters, when I worked for Ensign Bickford at their det cord plant we had them at various points along the process, if there was a detonation any where along the line the cutteres would auto fire and cut off the detonationm wave (the cord detonating

I am going to approach this, that the company is full filling a military government contract and in the contract is says to comply with DoD 4145.26m Contractor Explosive Safety Manual, from it I can find a dozen or so military references to using crimpers. Will see
 
I was introduced to the hose cutters after leaving the military. My military EOD training was always "use a sharp knife". Commercial training has always been along the lines of "sharp knife or guillotine action" and "avoid anything that imparts either an abrasive (saw type) action or shear (scissors) action".
 
I went through the same military system as Danny (exat808), where we were taught to use a sharp knife, on det cord and on metal sheathed linear cutting charges (CLC = charge linear cutting). I took around with me as a base for placing under the det cord / CLC a piece of the flat wooden packing found in inner containers for PE4, so I could safely apply enough downward force to cut without sawing and without harming myself. I tried tinsnips on det cord and also used a blunter knife sometimes but wasn't happy at having PETN leak from the end, it seemed a waste to me and could have resulted in air gaps further along in the filling.
 
US Military is to yuse the M 2 crimpers, and for data sheet is a sharp knife (I've used shears on past though). As for Flex linear (charge linaer cutting) I found my KBar did just fine.

I also found that M2 crimpers gave me a better cut, as for PETN leaking rom the end of the cord I found that depending on who made the cord, you'd either have a good cut or a leaking cut. Ensign Bickford was always a good cord, but that was becasue of a step they use in their process that increases the density of the PETN in the cord. ORICA cord (prior to them taking over Ensign Bickford) sucked. As does det cord that comes from Mexico and S. America, Chinese det cord I found it had a lot of gaps in it sometime wide enough to stop the detoantion wave.

I meet with the OSHA inspector who wrote the finding next Monday. WIll post what the outcome is. But as for me I'll always use crimpers, and if someone thinks that doing this stress's the PETN crystals and might cause an initation - my reply is then the cord is way too sensitve and would detonate by rough handling/dropping a spool, etc. I have made PETN for both explosive charges and det cord. the grain of PETN made makes a lot of difference, as does making sure the PETN is not acidic from the chemcial process (had more then a couple fires from this hapening) but that is prevented and/or discovered at the end of the process before it is put in use.
 
I would be interested in what the OSHA Inspector has to say - certainly from a training perspective. I have just spoken to a senior blasting contractor who confirms that UK best practice in the quarry and civil engineering industry is to use a sharp knife and avoid any metal to metal contact ( he also advocates the use of the hose cutters that I mentioned previously).
Our Institute of Quarrying explosives user guide makes no mention of cutting cord safely or otherwise.
I agree with the comments regarding inconsistencies in production standards. We experienced some misfires about 2 years ago with a batch of Brazilian 20g/m cord which was put determined to be caused by air gaps in the filling. We also routinely have to remind users about taping over reel ends to prevent PETN spillage.
The military still issue packs of rubber sleeves for their 10g/m cord.

Sharp knives are the order of the day for SX2 (Detasheet), and linear cutting charges such as ACE and BLADE.
 
I just finished an interview with an old explosive engineer who has worked with det cord and more recent flexlinera shapred carges, etc. First you made a good point about taping hte ned of the det cord to prevent it from dusting out. But again I rarely ever saw that problem with Ensign Bickford cords. During the interview the engineer kept jumping in and pulling me back to reality or ask the never ending question "why?". One of his points was that all the explosive rules we live by all come from several decades if not a century ago. One point (and it was just mentioned) no metal to metal with explosives, that first came about during manufacturing, and has been kept as a "one size fits all" statement. He also goes back to his years of handling explosives (going on 65 now) and can not find or remember there ever being a case where an explosive initiated (in the field) by cutting det cord with crimpers, cutting data sheet with shears (he tends the binder reduces the friction sensitivty - checked the MSDS and mil specs and he is right friction is not a big problem). He also reminded me that C4 made of RDX does not have a problem, again because of the binders. I got him back on track about det cord, wher he did make a point, the question of it being safe to cut det cord with M2 crimpers applies only to PETn loaded cords. There in the oil exploration business there are reports of cord being set off, of course there was normally not enough left to prove it wa crimpers, but thay cause made the most sense. He went on to give me a chemistry lesson, that I could not follow, but the bottom line was PETN used in 20 to 100 gr/ft cord uses a CAP Grade PETN which for a 50 lb batch of PETN, the following is added.
Antistatic Plasticizer (APKA) (See Note)
01700​

​
0.075 pound
Silicone 36 Emulsion (See Note)
41105​

​
0.375 pound
Now this is US Mil det cord, but the added materials not only address static but also friction. Monday I meet with OSHA, will see where that goes, but I am ready to make my point.







 
The crimper issue has been bugging me and after a bit of research in my files I have found a reference in a 2005 Dyno-Nobel Product Guide (USA/Canada version).

Link here -
http://www.dynonobel.com/files/2010/08/ProductAppGuideNONELDetCord.pdf

The red text box on Page 46 seems to be quite definitive -
Never
cut detonating cord with
devices such as scissors, pliertype
cutters, cap crimpers, wire
cutters, or similar instruments that
produce metal-to-metal contact.
 
Don't disagree with what is posted bythe manufcatures - I've have read several of them, but every US demolition manual I have looked into from WW1 through the most recent ones and the EOD pubs all say M2 crimpers are used to cut det cord, time fuse and to crimp non electric caps to cords. How can we argue with over a 100 years of a practice that has never once (at least not documetned) caused an accident (again with mil det cords).
 
Nobels_Instruction_Regrading_Cutting_DetCord.jpg
From page #46 in the .pdf file that exat808 is linking to.
 
OK I got the Federal Safety OSHA citation dropped. I pointed out that the company was operating under a DoD Army Contract and that they had to comply with Contractor Explosive Safety Manual, which naturally would refer them to various DoD and DA explosive safety requirements and use manuals. I opened up the 3 Army references that clearly said use crimpers. Though the citation was dropped (becasue of previous problems would have been about a $15,000 fine) we agreed to examin and look for another way to cut the cord that would help statisfy the manufacturers comments. The company has agreed to use razor knifes now. I asked the OSHA inspector and his boss what about the furture if this comes up again at another company or location. They said while they agreed with my defense and (almost shit my pants) agreed that from the history, science and DoDs position, they (this office at least) would not cite the practice again, but would provide a Best Management statement to the company in question that the cord manufacture recommend razor cutter and not crimper. Yeah me, just put $3000.00 in my pocket for this job.
 
weberoed said:
ok i got the federal safety osha citation dropped. I pointed out that the company was operating under a dod army contract and that they had to comply with contractor explosive safety manual, which naturally would refer them to various dod and da explosive safety requirements and use manuals. I opened up the 3 army references that clearly said use crimpers. Though the citation was dropped (becasue of previous problems would have been about a $15,000 fine) we agreed to examin and look for another way to cut the cord that would help statisfy the manufacturers comments. The company has agreed to use razor knifes now. I asked the osha inspector and his boss what about the furture if this comes up again at another company or location. They said while they agreed with my defense and (almost shit my pants) agreed that from the history, science and dods position, they (this office at least) would not cite the practice again, but would provide a best management statement to the company in question that the cord manufacture recommend razor cutter and not crimper. Yeah me, just put $3000.00 in my pocket for this job.
Click to expand...

good job!!!!!
 
Thank you for the update. I am wondering how our HSE ( the UK equivalent of OSHA) would have dealt with this scenario. Glad to hear you got paid too!
Stay safe.
 
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