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Chapter 19
Use of High Strength Steel
19.1 Review of Usage of High Strength Steel Linepipes
19.1.1 Usage of X70 Linepipe
i) General
Grade X70 is now widely used for high pressure transmission lines in many countries. The
supplier reference lists summarized in Table 19.1 provides 94 project references for 4
suppliers. This list is indicative rather than comprehensive, as other manufacturers have
supplied this grade of material. A pipeline project installed in July 1997 for BP in the North
Sea involves the laying of a grade X70, 24-inch diameter pipeline with a wall thickness of
25.8 mm.
A detailed discussion on materials and design of high strength pipeline is given by Bai et a].
(2000).
The reference list also shows only limited subsea use of X70 material, refer to Table 19.2.
Again, these references are only indicative and not comprehensive.
ii) Oman-India Gas Pipeline
Discovery of extensive natural gas reserves in central Oman in the late 1980’s and early
1990’s has provided the opportunity for development of several potentially attractive gas-
based energy ventures. In June 1993 a study was initiated to establish the feasibility of
installing a subsea pipeline to connect the gas reserves in Oman to markets in India. The
preliminary route of over 1,100 km would provide a direct link between Oman and India
across the Arabian Sea with water depths up to 3,500 m. The Oman-India Gas Pipeline (0-
IGP) project is currently on hold and design has not progressed past the preliminary stages,
which is essentially feasibility engineering.