Method of preparing a pipe-section

A method of forming a pipeline comprising a plurality of conjoined pipe-sections comprising the steps of:

• providing at least two pipe-sections;
• providing a pre-heat treatment to the ends of the pipe-sections to be joined;
• and
• girth welding the two pipe-sections together;
• wherein each pipe-section is formed in a method comprising at least the steps of:
• (i) providing a seam-welded pipe-section having first and second pipe-ends and a seam weld;
• (ii) defining a first portion L1 of the longitudinal length of the pipe-section from the first pipe-end being in the range 3% to 40% of the overall length of the pipe-section;
• (iii) defining a second portion L2 of the longitudinal length of the pipe-section from the end of the first portion LI towards the second pipe-end;
• (iv) heating at least the first portion L1 to at least a first temperature T1 of at least 500° C. for at least 2 minutes;
• and
• (v) maintaining a second temperature T2 of the second portion L2 during step (iv) below the first temperature T1,
• (vi) defining a third portion L3 of the longitudinal length of the pipe-section from the second pipe-end being in the range 3% to 40% of the overall length of the pipe-section, and defining the second portion L2 as the intermediate longitudinal length of the pipe-section between the end of the first portion LI and the end of the third portion L3;
• (vii) heating the first portion L1 and the third portion L3 to at least the first temperature T1 of at least 500° C. for at least 2 minutes;
• and
• (viii) maintaining the second temperature T2 of the second portion L2 during the heating of the first portion LI and the third portion L3 below the first temperature T1,
• wherein the seam weld is helical or parallel to the longitudinal axis of the pipe-section, and wherein step (i) comprises the steps of
• preparing a metal plate or strip;
• forming said metal plate or strip into a tube having first and second pipe-ends;
• and
• performing at least one seam weld along the tube to join the edges of the metal plate or strip to form the pipe-section.