Heat resisting metal tube and method for manufacturing same

摘要

A multi-layered heat resistant metal tube is disclosed. This tube has excellent anti-coking characteristics and is suitable for use under the conditions where carbon tends to deposit and accumulate thereon due to contacting with hydrocarbons at a high temperature. The tube is made by forming weld-mounted overlaid layer of a Cr-Ni-Mo alloy by building-up welding over the inner surface and/or the outer surface of a substrate tube made of a heat resistant metal. The Cr-Ni-Mo alloy consists essentially of, by weight %, Cr: 36-49 wt%, Ni: 35-63 wt% and Mo: 0.5-5 wt%. Building-up welding is preferably carried out by PPW (Plasma Powder Welding) in which the filler metal is supplied in the form of powder. <IMAGE>