A method of commissioning a subsea hydrocarbon well by connecting a double-walled floor to surface pipe 10 to the wellhead. The pipe being formed from multiple threaded segments connected together to form the pipe. The pipe preferably comprises a single walled inner pipe 1 having threaded ends and a skirt or bayonet piece 3 which extends from the female threaded end 6 of the inner pipe. The inner pipe and the skirt having insulating material 5a, 5b, 5c disposed around them and an outer pipe 2 and cover piece 4 covers the insulating material on the inner pipe and skirt respectively. The threaded ends of the inner pipe are preferably reinforced sections with a diameter larger than the central part of the pipe. The skirt being connected to the reinforced section on the female threaded end 6 of the inner pipe and the outer pipe being connected to the reinforced section of the male threaded end 7 of the inner pipe.
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