The most essential pipeline design criterion is, of course, the pressure containment or bursting criterion normally determining the pipe wall thickness. When the pressure containment is ensured, the concern is often towards the action of the combined loading; pressure, axial force and bending moment. The combined loading criterion typically governs the installation and also set up requirements for other design issues such as seabed intervention and global buckling.
The combined loading criterion of DNV GL submarine pipeline systems standard, DNV-OS-F101 or DNVGL-ST-F101 which is its new name [1], has been modified several times, and the current version was introduced in its present form in the 2007 revision of the offshore pipeline standard. This paper discusses the current criterion for combined loading, i.e. bending moment capacity, when the pipeline is under influence of axial force and internal over-pressure. The criterion is compared with several other similar criteria from previous revisions of the DNV GL pipeline and riser standards and from other offshore pipeline standards. In addition a comparison with physical and numerical tests is given, while the background and derivation of the criterion are given in an accompanying paper by Collberg and Levold [2].
