Yellowjackets line piercing tool will only work on copper lines but not on steel lines so I made a saddle, nipple welded on, attached ball valve and a fitting for a hose. I open the valve, put a drill through it and tap the line. I withdraw the bit enough to close the gate valve. I lose some ammonia but I am wearing a full face cover and and gas mask. I did 40 or fridges and then had one flare on me... 8 feet straight out; lasted only a second. That got my attention. I did a couple more and then when I tapped a small fridge and the ammonia came out, it exploded. No harm done but it buts this procedure on hold. Comments or input please.