February 2018

CD2 Weld Overlay

Corrosion protection on short plant shut-down timeline

A 5.5m diameter continuous digester pressure vessel in a kraft pulp mill required 350m2 of stainless steel weld overlay corrosion protection to its internal surface for service life preservation. MEL were engaged for overall project development and management. The works could only take place while the plant was shut down for an extended period governed by the time required to complete this project. Therefore the works were carried out on a 24/7 basis, utilising 9500 man hours over 16 days to complete.

Specialist international weld overlay contractors were engaged to operate a mechanised welding process with multiple local contractors engaged to provide supporting activities. The job site was structured with the weld area broken out into 6 welding zones 3 metres to 4 metres in length. The overlay used over 20 Tonne of duplex stainless-steel welding wire, 40 tonne argon m3 and was all managed through a 1.2 metre diameter access port.