Abstract: A filter press electrolyzer, such as for use in a chlor-alkali cell, has electrode assemblies which include a pan-shaped structure. The pan members have a planar floor and an upright side around the peripheral edge of the floor. The upright side terminates upwardly in a rim. The pan members are elongate, thereby providing long, at least substantially parallel sides at long pan edges as well as short sides at the top and bottom of the pan. On the pan floor are a series of parallel, rigid stand-offs, which project upwardly from the floor. These hold electrodes away from the back of the pan. These electrodes are typically large, somewhat flexible and at least substantially planar members, usually made of metal mesh. The stand-offs can include principal stand-offs located at the central area of the pan, plus additional stand-offs, typically one each at the top and bottom of the pan.

Abstract: Electrodes such as mesh electrodes can be in configurations where they are separated from electrode back pans by standoffs. The mesh electrodes are very adherently secured to the standoffs. When the electrodes are in need of repair, removal and refurbishing can be a problem. There is now disclosed a method of electrode repair which in large part retains original structure by first removing the mesh electrode and then at least substantially the top of the standoff. A replacement standoff assembly is placed against the retained portion of the original standoff and secured thereto. Refurbished or new electrode mesh can be adhered to the resulting replacement standoff. This may include welding of mesh electrode strands utilizing weld nuggets which are substantially the size of the strands. The refurbishing technique can maintain original separation distances between the back pan and the electrode.

Abstract: A welding tool is disclosed comprising a working electrode and a ground electrode. A tool body comprises means for holding the electrodes in a contiguous, spaced-apart, side-by-side relationship. The electrodes are movable along parallel axes to and away from the tool body. A first compression spring biases the working electrode away from the tool body, and a second compression spring biases the ground electrode away from the tool body. The electrodes comprise stops by which the electrodes are positioned at a predetermined distance from the tool body against the bias of the compression springs. A switch responsive to movement of the working electrode, on movement from said predetermined distance toward the tool body, closes an electrical circuit to supply power to the electrodes. The welding tool comprises means by which the electrodes can be applied to a common side of the workpieces being welded, or to opposite aligned sides of the workpieces being welded.