Abstract: A removable top closure and venting assembly for the tubular housing of a control rod drive includes a mounting ring threadably inserted in the upper end of the housing, a fluid-sealing closure member beneath the mounting ring and which is mounted in and coupled to the mounting ring by means of a ball and socket joint, a gas vent defined by interconnecting passages extending through the closure and through the ball and socket joint, and a vent valve accesible from the top of the closure assembly.

Abstract: A ballasting system for oil tankers and other ships for separating the oil nd the water ballast which eliminates oil contamination and pollution in ballasting and deballasting ships. Flexible fabric-reinforced or stretchable membranes are attached in liquid sealing relationship within the oil tank all around at the athwartships quarter-points to thereby preclude flow between the oil and ballast water. Ballast water is contained in the tank on one side of the membranes while the oil cargo or the flowable cargo is separated on the other side of the membranes. The entire tank can be maintained full for ship stability and prevention of sloshing of the fluids.