The use of corrosion resistant alloys (CRA's) is well-established for the prevention of internal corrosion in flowlines transporting multi-phase fluids from well-heads to processing facilities. The CRA is present in such flowlines either in the form of a thin layer metallurgically bonded to the inner surface of the pipe, called 'clad pipe', or as a separate layer of CRA material that has a relatively weaker mechanical bond with the carbon steel pipe, called 'lined pipe'. The former has been used in a number of projects in which the fluids are flowing at high temperatures that are likely to cause the flowline to develop global buckles, and hence high levels of longitudinal compressive strains, during operation. The conventional view is that such high compressive strains will cause the liner to buckle. Accordingly, the use of CRA lined pipe has previously been restricted to pipelines that either would be subjected to moderate temperatures, say <40oC, or to high temperature flowlines that have been prevented from buckling globally by the use of trenching and burial or covering with crushed rock. The use of CRA clad pipe incurs a cost penalty when compared to the corresponding lined pipe. This is an incentive to re-evaluate the compressive strain capacity of lined pipe. In particular, the possibility of applying internal pressure as a means of stabilising and preventing local buckling of the liner if the lined pipe were to be subjected to high levels of compressive axial strains due to bending.
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