To provide a leakage detecting method capable of surely detecting leakage at the time of a leakage test by positively discharging to the outside a leak due to a nailing mistake.
In the leakage detecting method, a joint for a metal flexible pipe comprising a joint body 1 and a nut 3 to detect gas leaked from the metal flexible pipe in which the outer surface of a metal corrugated pipe 70 passing gas is coated with a synthetic resin layer 71. Gas leaking from the metal corrugated pipe reaches the joint for the metal flexible pipe through the clearance between the metal corrugated pipe and the synthetic resin layer, and passes through a selective permeation member 5 which allows gas to pass through and does not allow liquid to pass through. Thus, the leakage of gas can be detected by positively discharging the gas to the outside.
ANAMIZU TAKASHI
SATO FUMITAKA
OKI KATSUHIRO
UENO TOSHIYUKI
TOKYO GAS CO LTD
HITACHI METALS LTD