How do I properly attach the flex pipe to the gas stove on one end and the supply pipe on the other end? Do I need a gas poxy? If so what is the proper method of application--on both sides of the attachments (flex pipe and gas supply pipe/stove) or on just one, how much is enough? How tight do I screw the connection? Then when I switch on the turn off value, I test with soap and water for bubbles?