Due to the progressive exploitation of natural gas fields pipeline designers facing more and more challenging demands to ensure durable and safe operation conditions for their products. Besides a reliable application in arctic areas, in the deep sea or in seismically active regions the HIC resistance for H2S containing fluids is a key requirement which has to be fulfilled. Here, sophisticated pipe material and tailormade solutions for specific projects have to be developed.

Over the last decades EUROPIPE is looking back on a successful history in the delivery of sour service material based on TMCP plates. This paper gives an overview about EUROPIPE´s development activities and the contribution in actual pipeline projects to fortify the confidence in the use of TMCP material:

In the beginning adequate steel making practices for sour service material are presented. Afterwards the requirements for sour service steels and the benefits of TM rolling with accelerated cooling are introduced. Furthermore it is explained how the design concerning material grades and corrosion testing has developed in the past. An outlook on further developments will be given as well.

During a controlled TM rolling process the precipitation stages, grain refinement and microstructure of line pipe material can be adjusted to meet requirements which are needed for later operation. Accelerated cooling ensures a homogeneous material and restricts carbon redistribution and banded microstructures. These effects lead to a reduction of HIC and SSC initiation sites due to inhomogeneity. Nevertheless recent operator experience has questioned the general suitability of TMCP rolled products for sour service. From the pipe manufacturers position lean alloy designs below material grade X60 are considered unsuitable due to the resulting heavy wall thicknesses and the higher deformation rates in processing plates to pipe. On the other hand the developments towards even higher grades are influenced by discussions concerning an increased carbon content and local hard spots. The presented information will show that the use of grade X65 is technically justified and the recent research activities towards the implementation of higher grades shall be further considered and developed.

Due to given results pipeline operators and manufacturers are encouraged to maintain their fruitful cooperation in the development of high quality-products even for application under severe sour service conditions.

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