Abstract: A metallic tube for heating a medium or subject outside thereof or inside it by transfer of heat energy through walls of the tube, in which heat is absorbed or emitted at least to a substantial degree by radiation on one or both of the inner and outer surfaces of the tube, is of a material forming a layer of essentially Al2O3 on the surfaces thereof when heated to at least approximately 750° C. At least one of the external and the internal surface of the tube is coated by one of a metal, metal alloy and metal compound, which after oxidation forms a layer having an emissivity coefficient exceeding 0.7, or by a layer essentially consisting of a metal oxide which has an emissivity coefficient exceeding 0.7.

Abstract: A metallic tube for heating a medium or subject outside thereof or inside it by transfer of heat energy through walls of the tube, in which heat is absorbed or emitted at least to a substantial degree by radiation on one or both of the inner and outer surfaces of the tube, is of a material forming a layer of essentially Al2O3 on the surfaces thereof when heated to at least approximately 750° C. At least one of the external and the internal surface of the tube is coated by one of a metal, metal alloy and metal compound, which after oxidation forms a layer having an emissivity coefficient exceeding 0.7, or by a layer essentially consisting of a metal oxide which has an emissivity coefficient exceeding 0.7.

Abstract: A method of joining at least two components (1, 2), such as tubes, where at least one of the components (1, 2) comprises, or is made of, a material which is difficult to weld, comprises the step of welding the components together and then thermally insulating the weld joint (3) using a sleeve (4) for example.

Abstract: Method of joining at least two components (2, 3) utilising a fitting (1), where at least one of the components comprises, or is made of, a material which is difficult to weld. The components (2, 3) are provided with thicker walls at the end surfaces (6) that are to be joined. At least one of the thicker end walls is provided with an internal or external thread (T) and said at least two components are joined together by screwing said threaded end walls into and/or onto the fitting (1).

Abstract: The present invention relates to a method for joining two or more components and/or construction parts, at least one of which consists of a dispersion-strengthened alloy having the following composition (in % by weight): C up to 0.08 Si up to 0.7 Cr 10-25 Al 1-10 Mo 1.5-5 Mn up to 0.4 balance Fe as well as normally occurring impurities by the fact that the cross section in the joint is enlarged by forging before joining and where the product manufactured according to the method can be used in high-temperature applications at temperatures above 900° C.

Abstract: Radiant tube in a cracking furnace is disclosed. Hydrocarbons are cracked into ethylene in the tube through which hydrocarbons flow, which tube is heated from the outside to a temperature where cracking occurs. The tube is made from a FeCrAl material containing, in addition to Fe, 10 to 25% by weight of Cr, 1 to 10% by weight of Al and 1.5 to 5% by weight of Mo. Optionally, the material comprises up to a total of 2.2 wt. %, preferably up to 2.0 wt. % and more preferably up to 1.0 wt. %, of one or more alloying materials selected from the group consisting of tantalum, hafnium, zirconium, yttrium, nitrogen, carbon and oxygen.

Abstract: The invention provides a tube for use in furnaces where gas and liquid media are being passed through the tube from one end to the other while being subjected to substantial heating and decomposition resulting therefrom. The tube is made of a stainless iron-nickel-chromium-base alloy comprising in weight-% max 0.08% C, 23-27% Cr, 33-37% Ni, 1.3-1.8% Mn, 1.2-2% Si, 0.08-0.25% N, 0.01-0.15% rare earth metals, and Fe and usual impurities. The cylindrical tube has a smooth outer surface and an inner surface provided with valleys or recesses extending longitudinally with a smoothly curved bottom profile.