§ 11 Loads/actions, load/action effects and resistance
The design loads/actions that will form the basis for design and operation of installations, systems and equipment, shall be determined. When determining design loads/actions, the requirement to robust solutions, cf. Section 5, and the requirement to risk reduction, cf. the Framework Regulations Section 11, shall form the basis. The design loads/actions shall ensure that installations, systems or equipment will be designed such that relevant accidental loads/actions that can occur, do not result in unacceptable consequences, and shall, as a minimum, always withstand the dimensioning accidental load/action.
When determining design loads/actions, the effects of fire water shall not be considered. This applies to both fire loads/actions and explosive loads/actions.
Installations, systems and equipment that are included as elements in the realisation of main safety functions, cf. Section 7, shall as a minimum de designed such that dimensioning accidental loads/actions or dimensioning environmental loads/actions with an annual likelihood greater than or equal to 1x10-4, shall not result in loss of a main safety function.
When determining loads/actions, the effects of seabed subsidence over, or in connection with the reservoir, shall be considered.
Functional and environmental loads/actions shall be combined in the most unfavourable manner.
Facilities or parts of facilities shall be able to withstand the design loads/actions and probable combinations of these loads/actions at all times.
Section last changed: 01 January 2015
Design loads/actions as mentioned in the first subsection, comprise functional, environmental and accidental loads/actions, inter alia fire and explosive loads/actions, which form the basis for design and operation of installations, systems and equipment. As regards definitions of the terms design accidental load/action and dimensioning accidental load/action, reference is made to Section 3.
Functional loads/actions as mentioned in the fifth subsection, mean, in the case of load-bearing structures, permanent and variable loads/actions.
Dimensioning loads/actions as mentioned in the third and sixth subsection, comprise functional, environmental and accidental loads/actions, inter alia fire and explosive loads/actions.
In order to fulfil the requirements related to load-bearing structures, the standards NORSOK N-001 and NORSOK N-003 should be used. In addition, NORSOK N-004 should be used for steel structures.
In order to assess the loss of main safety functions as mentioned in the third subsection, the standard NORSOK Z-013 Appendix B should be used.
The NORSOK S-001 standard should be used for accidental loads/actions, in particular Chapter 5.6, in addition to other standards mentioned in these instructions. Special fire conditions such as jet fires, under-ventilated fires in modules, fire on the sea and the like may require additional calculation of fire loads / actions. For mobile facilities that are not production facilities, and that are registered in a national ship register, DNVGL-OS-A101 Paragraph 2 can be used as an alternative.
For facilities that are intended to leave the field due to bad weather forecasts, the values for environmental loads/actions connected with the least favourable of the following factors may be used:
- Conditions on the field when moving,
- Conditions during moving,
- Weather conditions at the planned new location, with the specified annual likelihoods in NORSOK N-003.
For mobile facilities registered in a national ship register, the loads/actions that the facility has been exposed to and the expected loads/actions during the period for which the consent for use is applied for, should be taken into account.
To fulfil the requirement regarding loads/actions, load/action effects, resistance and load combinations, the following standards should be used for pipeline systems: ISO 13623 Chapter 6 and DNVGL-ST-F101 Paragraphs 3, 4 and 5 for steel pipelines, DNVGL-ST-F201 Paragraphs 3, 4 and 5 for catenary metallic risers and API 17J Chapter 5 for flexible pipeline systems.
To fulfil the requirements regarding loads/actions, NORSOK D-001 Chapters 5 and 6 and D-010 Chapters 4 and 5 should be used for equipment for conduct of drilling and well activities and other well-related equipment, for example drilling risers, compensators, well control equipment, completion equipment and intervention equipment.
To fulfil the requirement regarding loads/actions, the NORSOK standard L-002, Chapter 6 should be used for pipeline systems in production plants.
If the loads/actions, load/action effects or resistance factors are uncertain, measurements or model experiments should be conducted to increase the quality of the analyses. The NORSOK standard N-003 should be used for model experiments on load-bearing structures.