This paper discusses two common problems, “weld tenting” and low coating thickness over the external
weld, and their causes in traditional three layer polyolefin pipeline coatings. To tackle these problems, a
new approach to applying multilayer polyolefin coating to pipes is introduced. The new system consists
of side-extruding high density polyethylene over a graded structure polyethylene (GSPE) coating. This
study demonstrates that the new coating approach can provide exceptionally uniform coverage of
external welds, successfully eliminate “weld tenting”, and significantly reduce residual stresses in the
coatings.