The straight settings produce a pipe whose OOS is less than 0.15%L typically, ±9mm when L is taken as 6m (i.e., radius of curvature: 500m), according to DNV.
The straightening process for Reel Lay System (RLS) can be illustrated as below:
It can be seen from the graph above that when the counter bending from the upper track is not enough, the pipe can be under-straight at lower track. Sometimes, the under-straight pipes can be desirable if it is controlled. The residual curvature method (RCM) is fundamentally a method for laying pipe with a controlled, pre-defined residual curvature.
The residual curvature method (RCM) can be an effective way for global expansion and buckling control. RCM may also be applied for free span reduction, tie-in loops, etc.
The implications from RCM on pipe rolls, pipeline integrity, installation limitations and trawl pull-over capacity must be considered to make RCM successful.
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