SP-6 Unbonded Outerwrap

"Polyguard SP-6™ Unbonded Outerwrap is a critical compoenent of the RD-6® Coating System.

SP-6™ consists of a strong non woven, felt-like polypropylene fabric. The product is engineered to provide high bursting strength and low tensile and elongation properties. The result is an outerwrap with improved soil stress resistance.

For years, the pipeline coating industry relied upon bonded outerwraps to protect the anti-corrosion coating layer from mechanical damages. However, permanent adhesion of the outerwrap to the corrosion coating layer is not desirable. The fabric, when unbonded, has the freedom to be moved by the forces of soil stress, independently of the coating over which it has been applied. When the outerwrap is bonded to the coating underneath, the soil stresses can be transferred to the anti-corrosion coating layer causing deformation thus allowing electrolyte to penetrate the coating to the substrate. "