The first ACA meeting of the year, held at the Surrey Hotel, Grey Lynn, on 21 st February 2019, was addressed by Barry Robinson, GM of SAFE Ltd, Drury, on the subject of “How surface heat can lead to premature failure and corrosion”.
Barry is also Chair of the Maintenance Engineering Society of NZ (MESENZ).The meeting Chair Raed El Sarraf welcomed visitors attending the meeting from Queensland, including Wayne Thomson who is on the ACA Board.
Barry commenced his presentation to the well-attended meeting with an account of how post-processing surface heating (grinding, gas heating & cutting, plasma & laser cutting, welding) can cause harmful ‘sensitization’ of austenitic stainless steels such as grade 304 Stainless Steel.
The lesson to be learned was that Stainless Steel fabricators should specify an “L” grade Stainless Steel (very low carbon) to avoid metallurgical surface damage from heating that may lead to intergranular corrosion on Stainless Steel.
Fabricators must also follow the welding procedure specification during fabrication and properly specify a post-fabrication cleanup.
Barry then outlined the effect of surface heating on carbon steels to form an undesirable martensitic phase on steel surfaces. The martensite formed on the steel surface can lead to cracks developing and then metal fatigue may be initiated at the cracks (stress raisers). He described several cases where this problem had occurred resulting in steel structure failures.
Barry moved on to describe undesirable issues that can occur if organic coatings, such as powder coatings and paint coatings on steel, are subjected to surface heating to remove old coatings. The results of this practice can again be serious and result in unintended consequences including corrosion of the steel substrate.
After an extensive Q&A session, Raed thanked Barry for his interesting presentation.
The ACA Auckland Division AGM followed.
The following members were elected to the ACA
Auckland Committee for 2019:
- Chair: Matt Vercoe.
- Secretary: Hanieh Ghominejad.
- Committee: Raed El Sarraf, Les Boulton, Reuben Reeves, Andrew Allan, Barry Robinson, Michael Williams
The incoming Chair, Matt Vercoe, thanked Raed for his contribution to ACA in his role as Auckland Chair over the past years.