In my house I have lead gas pipes running to gas fires. I have recently installed central heating and don't need these fires any more so I want the gas to be capped as close to the supply as possible to minimism the ammount of gas running through my house (my brother's house set on fire due to an old lead gas pipe. I've recently had a plumber look at this and he didn't seem sure as to whether he could cap these with screw on capping ends similar to what would be used on copper. My gut reaction is that they should be soldered?