Abstract: A pressure relief venting lid for sealing an opening and providing pressure regulation of a container. The lid has a support plate attached by four angularly spaced spring assemblies to a port cover for sealing a filler opening in a manway cover for the container. The support plate overlies the port cover for fixedly supporting the spring assemblies and cover while protecting the springs and cover from impact or shock. The spring assemblies are disposed between the support plate and port cover for sealing the cover against the opening and allowing the cover to unseat from the opening to regulate the pressure within the container. The spring assemblies are offset equal distances from the center of the port cover to minimize bending moments that the cover may be subjected to. The generally circular port cover has a convex dished portion for strengthening the port cover to maintain the seal with the opening while under load.