Patent ID: 8350178

Claim:
A method of providing a flat duplex stainless steel strip for an armouring layer of a flexible pipe, said method comprising providing at least two duplex stainless steel pieces each having an end-face and a thickness which is at least 10 times less than its width, welding said end-faces of said two pieces of duplex stainless steel together to form a welded interface section using resistance welding, allowing the welded interface section to cool down from an initial temperature during the welding where it is at least partly in liquid phase to a temperature y 1 of at least about 1100° C. without application of additional heat, whereafter a controlled cooling of said welded interface section is provided by applying heat in the form of current to reduce the cooling rate of the interface section at least for the cooling from about the temperature y 1 until the temperature of the interface section is a temperature y 2 of about 600° C. or less.