DRILL RAIDERS' CONCRETE TEST.
Byline: Examiner News Correspondent email@example.com
THIEVES who carried out a "sophisticated raid" on a deposit box firm could have spent hours drilling through two metres of reinforced concrete before entering the vault.
Scotland Yard Flying Squad Detective Chief Inspector Paul Johnson told how a heavy duty Hilti DD350 drill worth PS3,500 had been used to "bore holes into the vault wall" at the Hatton Garden building.
But secretary of the Drilling and Sawing Association Joel Vinsant said that even with high-tech equipment, it may have taken hours for the thieves to drill through two metres of reinforced concrete.
He said: "I imagine what they might have done is to bore several holes with a rig-based drill until they had made a space big enough to get through, rather than boring one hole and breaking through.
"It could have taken up to an hour per hole, unless the material was very weak, but we're talking about London concrete here."
Mr Vinsant said the thieves would have had experience in using the heavy duty drill, as it was "not something the average person would have". He said: "You have to really know what you're doing if you're using something like this.
"You should have training on how to use it, but the trouble is you can get hire companies now that will rent them out and they don't really care whether you are trained or not.
"If they weren't trained they could have seriously injured themselves or got the drill jammed."
Mr Vinsant said the Hilti DD350, which is typically used to drill holes for cables or ventilation systems, requires a constant supply of water so that it does not overheat.
He said: "This is a diamond core so it has got diamondimpregnated segments fitted to the end of the barrel that cuts through concrete.
"This means they would have had to have had a water supply to do this so that the drill didn't overheat.''
Scotland Yard Flying Squad Detective |Chief Inspector Paul Johnson outside Hatton Garden Safety Deposit Ltd