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Final report on Contract no. 7210-PR/058, 1 July 1997 to 31 December 2000

The aims of this project were the evaluation of the effect of pipe-forming on X100 plate material-fracture properties and the definition of safety criteria against fracture phenomena in large-diameter X100 SAW pipelines operating at very high hoop stress. The materials used were high-strength micro-alloyed steels obtained by means of a suitable combination of chemical composition and thermomechanical treatment parameters in order to have a correct balance between strength, toughness and weldability.

Two series of X100 plates of different thickness were made using controlled rolling and online accelerated cooling; The plates were then formed into pipes of two different diameters:
1. 56 inches OD x 19.1 mm wall thickness;
2. 36 inches OD x 16 mm wall thickness.

Experimental results obtained by an extensive full -scale test carried out on both single pipes and pipeline test sections have been used to establish the criteria for defect tolerance, ductile/brittle transition temperature evaluation and the crack arrest behaviour of X100 pipes. Moreover, the effect of the plate to pipe-forming process on the tensile and fracture properties has been evaluated by means of laboratory tests. The results show that the fracture behaviour of these pipes was good and demonstrate the real feasibility of these very high grade pipeline steels for new high pressure (>150 bar) long-distance gas transmission pipelines.

Additional information

Authors: MANNUCCI G, CSM, Rome (IT);HARRIS D, Corus UK Ltd, Rotherham (GB)
Bibliographic Reference: EUR 20330 EN (2002), pp.128. Euro: 19.00
Availability: EUR-OP reference: KI-NA-20330-EN-S Available from EUR-OP sales agents. URL:
ISBN: ISBN: 92-894-3652-2
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