Pipe Laying

There is a need for bends in every pipeline to accommodate gradual or abrupt directional changes. Conventional pipelines use three types of bend:

• Elastic bends – where the pipe is allowed to bend elastically and elastic stresses remain in the pipeline
• Cold bends where the pipe is bent plastically in the field using a bending machine - usually to a radius of 40D and angle <15 degrees
• Hot induction bends where the pipe is heated and bent to a radius of 5D and angle <90 degrees

Finite element analysis of specific designs of 12-inch diameter pipe have shown that the SPS pipe system has sufficient inherent flexibility to lay pipe directly into the trench and follow terrain without the need for cold bends.  

• The elastic limit is typically 100D when it would be 300D for conventional pipe
• If 1% local plastic strains are allowed, then 40D bends can be accommodated as part of the normal lay process without the need for a bending machine