DAVID WILLIAM TREADWELL
Engineering in North Belle Vernon, PA

6089399, Jul 18, 2000

Oct 23, 1997

8/956605

John Wayne Felbaum - Greensburg PA
David William Treadwell - Belle Vernon PA
Joseph Tassone - White Oak PA

Chatwins Group, Inc. - Pittsburgh PA

B65D 2514

220582

A seamless steel-body cylinder, suitable for storing ultra-high purity gases, has an inert metal lining. The cylinder lining is preferably nickel and completely covers the interior surface of the steel cylinder body, preventing the stored gas from making any contact and reacting with the steel cylinder body. The surface of the inert metal lining is conditioned to be smooth, preferably to 15 R. sub. a or better. The cylinder body is preferably externally threaded to secure end closure devices to the cylinder body. A process for making the cylinder comprises the steps of cutting a seamless steel pipe to form a cylinder body, conditioning the surface of the cylinder body, optionally thermomechanically working the cylinder body ends to altered diameters, descaling the interior surface, electroplating an inert metal layer on the cylinder interior, heat treating, machining threads into the exterior surface at the cylinder ends, machining the inside diameters of the cylinder ends, conditioning the inert metal surface to smoothen it and sealing the cylinder ends with end closure devices which are secured by securing devices to the threads on the exterior of the cylinder body.