Development of pipeline design sheets in MathCad

The purpose of the project was to create a set of standardised Mathcad sheets to allow a number of issues relating to the design of subsea pipelines to be assessed consistently throughout the client's company.

These included MathCad sheets to:

• Calculate the distance between rockdump stitches in order to control lateral buckling, both for a single pipeline and a pipe-in-pipe system
  
• Calculate the fatigue life of a pipeline stabilised by rockdump stitches.  The effects of tidal, wave, pressure and temperature cycles on the spans between successive stitches were assessed and the required spacing of rockdumps to prevent fatigue failure within a given design life was determined
  
• Calculate the required wall thickness of a pipeline according to both the API 1111 and DNV OS-F101 pipeline design codes
  
• Perform dropped object design for a pipeline, taking into account the probability of impact, the impact energy, the associated dent size and fatigue life of the dented pipe and suitable protection methods to prevent denting
  
• Design a pipeline crossing, assessing the stresses in the pipeline, the types of support, the volume of rock required for protection of the crossing and the settlement of the crossing and associated rockdump protection.  Upheaval buckling of the crossing pipeline and VIV of the temporary crossing spans were also assessed