A releasable and gas tight sealing apparatus for construction panels of a paint baking oven which relieves the buildup of gas pressure within the oven in the event of an explosion. The apparatus has tongue and groove members and a compressible cord rope received in the groove members. In assembly and during normal use of the oven, the tongue is received in the groove and bears on and compresses the cord rope to provide a gas tight seal. In the event of an explosion, the construction panels are forced outwardly which disengages the tongue and groove members and relieves the buildup of gas pressure in the oven.