Composite Tube

Abstract

A composite tube having a corrosion resistant member and a load-bearing member is provided. The corrosion resistant member is a Cu—Al alloy and has a wall thickness of at least 0.5 mm, while the load-bearing member is a Fe, Ni or Co based alloy having a wall thickness of at least 1 mm. The composite tube can be manufactured by conventional means like extrusion, rolling, welding etc. The composite tube is to be used in environments where the risk of metal dusting, coking or carburization is high

1 . A composite tube comprising at least one corrosion resistant member and one load-carrying member wherein the corrosion resistant member is a Cu—Al alloy in a thickness of at least 0.5 mm, and wherein the load-carrying member is an alloy based on Fe, Ni or Co, in a thickness of 1-15 mm. 
     
     
         2 . A composite tube according to  claim 1  wherein the corrosion resistant member is located on the inside and/or outside of the load-bearing member. 
     
     
         3 . A composite tube according to  claim 1  wherein the corrosion resistant member is metallurgically bonded to the load-bearing member at least along a part of a contact surface between the corrosion resistant member and the load-bearing member. 
     
     
         4 . A composite tube according to  claim 1 , wherein the composition of the Cu—Al alloy is (all in weight %):
 Al 2-20 
 Si >0-6 
 Fe+Ni+Co+Mn 0-20 
 REM 0-3 
 balance Cu and normally occurring alloying additions and impurities. 
 
     
     
         5 . A composite tube according to  claim 1 , wherein the tube has an outer diameter of 10-400 mm. 
     
     
         6 . A composite tube according to  claim 1 , wherein the tube has a total wall thickness of 1.5-20 mm. 
     
     
         7 . Method of producing a composite tube according to  claim 1 , comprising providing the load-bearing tube applying the corrosion resistant tube onto the load-bearing tube by overlay welding. 
     
     
         8 . Method of inhibiting metal dusting, carburization and/or coking in environments where the activity of carbon is about 1 or higher comprising forming construction material from the composite tube according to  claim 1 . 
     
     
         9 . Method according to  claim 8  wherein the corrosion resistant member is located closest to the environment where the activity of carbon is about 1 or higher. 
     
     
         10 . A composite tube according to  claim 3  wherein the corrosion resistant member is metallurgically bonded to the load-bearing member at least along 60% of the contact surface between the corrosion resistant member and the load-bearing member. 
     
     
         11 . A composite tube according to  claim 5 , wherein the tube has an outer diameter of 35-200 mm.