I have 3/4 inch gas line in a closet and I want to remove the line as I have taken out the appliance it was serving.  The pipe is capped now with a screw on cap , when I cut the line do I have to use  a threaded cap / attemting to put threads on the end of the cut pipe will very diificult.  Is there another way of sealing the end of the pipe?  Could I use a epoxy cement for metal and bond the threaded cap to the end?  Is this safe , could it leak in future?