ANALYSIS OF THERMAL RESIDUAL STRESS ON LARGE THICKNESS POLYPROPYLENE JOINTS AS IN A REEL-LAY SYSTEM

The purpose of this document is to be an initial study into the affects that increased insulation thickness requirements have on a typical field joint. An observed increase in joint failures has begun to occur with larger insulation thickness requirements which requires justification as to a possible and probable cause. The method of failure that is looked into in this document is the increase in comparative stress at the bonding joints caused by the increased stress of the comparatively increased thermal shrinkage and resultant residual thermal stress. This is analyzed through an ABAQUS simulation for current stress of the common 3in insulation thickness and the resultant stress of increasing the insulation to a 4 in thickness. The increase in stress upwards of 30% can be a cause of concern when paired with bending due to the requirements of reel lay installation methods.