Abstract: An improved gate valve having a body with an inlet into the valve chamber and an outlet from the chamber, a gate in the chamber, a bonnet with an opening therethrough, secured to the body, a stem connected to operate the gate and extending through the bonnet opening, a seat in the bonnet, a shoulder on the stem, heat responsive means holding the stem out of back seating position during normal operation and releasing to back seat responsive to excess heat, body bushing surrounding said inlet and outlet and sealing against the gate, each of the bushings having resilient sealing means and a sealing lip for sealing against a sealing surface on said body.