Abstract: A heater on metal composite unit. A strip of metal has a stripe of an electrically insulative and thermally conductive synthetic resin material bonded to one surface along the length thereof. At least one stripe of an electrically conductive material, having a width less than the width of the insulative stripe, is bonded to the surface of the insulative stripe along the length thereof. A strip of electrical resistance material at least partially overlies the stripes of both the conductive and insulative materials thereby providing a path of electrical resistance material from the conductive stripe transversely across a portion of the width of the insulative stripe whereby when electrical current flows through the electrical resistance material it will supply heat to the metal strip. Apparatus and a process for fabricating these composite units are also disclosed.

Abstract: A device used during fusion butt-welding between the ends of tubes to form a backing for the weld inside the tubes. The device comprises a thin flexible metal support strip having end portions which are overlapped to provide an arcuate outer peripheral surface, means guiding the overlapping end portions for relative longitudinal sliding movement to change the peripheral circumference of the support strip, and means for biasing the end portions in a direction to increase the peripheral circumference of the device. For use, the circumference of the support strip is decreased in opposition to the biasing means, and a backing strip of refractory material is secured on the periphery of the support strip. Next the device is positioned with the backing strip adjacent the inner surfaces of and bridging the ends of the tubes to be welded. The device is activated so that the biasing for the support strip will press the backing strip into engagement with the tubes, and the tubes are ready for welding.

Abstract: An impervious wall structure including at least two panels welded along adjoining vertical edges. Stress relief structure is on the panels to facilitate welding of the panels without undesirable deformation thereof. Finally, support structure is provided to assist in reinforcing the panels thereby providing a continuous impervious wall structure adaptable for use over large areas.