Abstract: The invention has as an object thereof to provide a welding method which is capable of forming an oxide passivated film, which is corrosion resistant, non-catalytic, and has an extremely small amount of released gasses, chiefly on the welded portion or in the vicinity thereof during the welding process. During the welding process, a gas in which 800 ppm.about.2.5% of moisture is contained in an inert gas is caused to flow, and a passivated film having chromium oxide as a chief component thereof is formed on the surface of the welded portion. The welding method comprises a welding process and a passivation process; in the passivation process, a gas in which 1000 ppm.about.2.5% of moisture is contained in an inert gas is employed.

Abstract: It is a metal oxidation treatment apparatus for carrying out the inactivation treatment of metal tubes used especially in a super high purity gas piping system and an apparatus of super high vacuum.The support part of a support member is made as a tubular form member, and a tapered part is provided on the outer periphery thereof, and further, since a spring is mounted to be displaceable, even if fluctuation is present in the internal diameter of stainless steel tubes, it is possible to let the stainless tubes easily be supported on the support part. Also, even fluctuation of the length is present in the stainless steel tubes, the support member is always pushed to the stainless steel tubes. Oxidative gas diffusing out of the tube to be treated to the outside thereof can be released to the outside of the oxidation treatment furnace without letting it contact to the tube to be treated.

Abstract: A bevel cutting device for cutting a bevel in a workpiece includes a frame and a vertical cutting torch, disposed on the frame, for cutting a root face of the workpiece. At least one bevel cutting torch is provided for cutting a bevel in the workpiece. The bevel cutting torch is disposed in parallel with the vertical cutting torch in a plate-cutting direction. An inclining section is coupled to the frame and inclines the bevel cutting torch about an axis parallel to the plate-cutting direction. The inclining section includes a motor gear disposed inside a casing and a link mechanism driven by the motor gear. The link mechanism is coupled to the bevel cutting torch. A shifting section is coupled to the frame and shifts the inclining section in a direction perpendicular to the plate-cutting direction.

Abstract: A plate cutting device having a cutting member for cutting a workpiece vertically or aslant comprises a stand and the cutting member coupled with a hose or a cord, an end of the hose or cord being connected to a part of said stand. An inclining device for inclining the cutting member about an axis parallel to a cutting direction is provided with the plate cutting device. A swinging device is coupled with the inclining device for changing the pointing direction of the cutting member with respect to the plate cutting direction. A cutting member holder is attached to the inclining device, for holding said cutting member so as to allow it to revolve with respect to the inclining device. Therefore, when the cutting member is swung and the hose or cord begins to twist, the holder will revolve and allow the hose or cord to untwist.

Abstract: A metal oxidation treatment apparatus to form the passivation film on the surface of the metal to be oxidized such as stainless steel or the like, comprising an oxidation furnace, a gas inlet to introduce gas into said oxidation furnace, a discharge outlet to discharge the gas from said oxidation furnace, and a heater to heat said oxidation furnace to the predetermined temperature, so that the metal to be oxidized is heated and oxidized in dry oxidation atmosphere while gas is passed in said oxidation furnace.