Method of welding duplex stainless steel strip for the production of an armouring layer of a flexible pipe

A method of providing a 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,
• welding said end-faces of said two pieces of duplex stainless steel together to form a welded interface section using resistance welding, and
• providing a controlled cooling of said welded interface section.

An apparatus for welding duplex stainless steel pieces together wherein the duplex stainless steel pieces each comprise an end part with an end-face, said apparatus comprises a pair of conductive platens capable of holding the duplex stainless steel pieces in their respective end parts, said pair of conductive platens being movable relative to each other and arranged to bring said end faces in contact with each other, and said pair of conductive platens being capable of heating said respective end parts of said duplex stainless steel pieces, wherein said apparatus further comprises a computer programmed to apply current through said conductive platens to heat said end parts to a sufficient level to weld said end-faces together to form an interface section, and allowing said interface section to cool under controlled conditions comprising applying current through said conductive platens during at least a part of the cooling of the interface section.