Appendices 
127 
Suffosion 
Suffosion (erosion by solution, surface solution) is the rearrangement of fine soil particles by 
water flow. Fine grains of irregular cohesionless soil are transported by the flow force of the 
water through the pore space. 
Support Structure 
The support structure supports the installation. 
The support structure of an offshore structure as referred to in this standard encompasses all 
the structural components and facilities that are located between the seabed and the operati 
onal structure (please refer to Fig. 1 -1 and Fig. 1 -2), except the foundation elements. 
A component of a structure may have its own support structure (e.g. topside). 
Test and Inspection Plan of the Periodic Inspections 
List of the schedule and content of the planned tests and possible inspections pertaining to 
periodic inspections. The test and inspection plan for periodic inspections is compiled by the 
operator and coordinated with the appointed inspector. 
Testing 
Controlling measure conducted by independent, qualified and recognised third parties in or 
der to determine and evaluate the actual state of the object to be inspected (system, technical 
medium, object, etc.). 
Topside (Operational Structure) 
Upper structure of an offshore substation that is located on top of a substructure and contains 
the entire technology or equipment necessary for operation (operational structure). 
Tripile Structure 
Part of a support structure where the (three) foundation piles are led above the water level and 
then joined in a top structure. 
Tripod Structure 
Part of a support structure where a steel pipe is placed on top of a tripod made of steel pipes. 
The struts of the tripod may consist of one or several piles. The foundation is achieved by 
connecting piles to a tripod. 
Truss Construction 
Please refer to Jacket Structure 
Ultimate Limit State (ULS) 
Any state that is associated to the collapse or any other form of failure of the support struc 
ture. This generally corresponds to the greatest load-bearing capacity of the support structure 
or supporting components. 
With regard to the foundation, this limit state is reached when the resistance increases to such 
an extent that an intolerably high strain is placed on the subsoil, the foundation elements or 
their components. 
Unmanned Offshore Substation 
An offshore substation is considered as being unmanned, if a scheduled stay only takes place 
during working hours; there are no planned overnight stays.