VIBRATIONS ASSOCIATION of NEW ZEALAND VANZ is New Zealand’s and Australia’s premier association of industry experts and practioners who actively specialise in: • ASSET MANAGEMENT & RELIABILITY IMPLEMENTATION • CONDITION MONITORING • RELIABILITY IMPROVEMENT Attend the VANZ conference and learn! Join us at the VANZ Conference to gain knowledge, share successes (and frustrations), network with your peers, and enjoy yourself! The 2017 conference will be held at the Novotel Lakeside Hotel, Rotorua - May 16th, 17th & 18th. See you there! www.engineeringnews.co.nz 9 VANZconference2017 28th Annual Conference. May 16th, 17th & 18th NOVOTEL Rotorua Lakeside Hotel, New Zealand Learn more and register at vanz.org.nz 2017 Conference Sponsor EN154 N E W S Developments in electropolishing have led to a safer and more time efficient method for cleaning and matching stainless steel finishes. The traditional and widely used process of pickling will typically take more time than DC electropolishing machines. Pickling is the process of removing weld scale from the surface of a weld by cutting away some of the layers that have been affected by the weld using acid concentrations. Acid pickling is a hazardous procedure with both human health and environmental issues to be considered due to the toxic acids used in the various processes. If not carefully controlled, acid cleaning can also cause damage to the surface and may result in further contamination on the treated areas. Acid concentrations, temperatures and contact times must therefore be closely monitored and controlled in relation to the treated alloy. When following OHS regulations the setup, use, and disposal of all pickling pastes becomes a costly exercise in both time and money; and, although pickling removes the oxide scale, the weld area is still chromium depleted compared to the parent metal. Research completed by the Intelligent Polymer Research Institute, University of Wollongong shows that welds cleaned with direct current electrochemical brushes like the Easykleen machines have significantly better corrosion resistance than pickling paste and/ or an electrochemical cleaning brush using alternating current. Weld Treated with mepBLITz Weld Treated with Pickling Paste HF Stainless steel electropolishing machines clean up the mess “Welds cleaned with an Easykleen Plus machine using DC have significantly better corrosion resistance due to reduced micro scale and removal of large grain boundaries which lead to pitting (corrosion) than Pickling Paste and an electrochemical Cleaning Brush using Alternating Current AC. AC also show signs of contamination,” according to the Intelligent Polymer Research Institute University of Wollongong, NSW. This increased corrosion resistance is due to reduced micro scale and removal of large grain boundaries which lead to pitting (corrosion) on the steel surface. Electropolishing machines such as the mepBLITz DC – i5 mobile electropolisher, Easykleen Pro and Easykleen Plus have been designed in relation to these studies and when used correctly result in a cleaner weld finish. By using DC, the machines selectively dissolve the microscopic high points of the stainless and selectively remove iron. Studies have also found that DC electropolishing will improve the chromium density at the welded area beyond that of the parent metal. This means that the days of the ‘Tea Stain’ weld zone are over: the area around the weld can be quickly and effectively polished to original, or better than original, corrosion resistance. “The largest improvement in corrosion resistance was demonstrated by the mepBLITz with the carbon fibre brush, which exceeded the performance of the pickling paste and returned the overall corrosion resistance of the entire weldment close to and in some areas exceeding that of the parent metal,” says Dr Ian Ward, Sandvik Materials Technology, Australia.
EN-Mar17-Digi
To see the actual publication please follow the link above