Inspection Trends / Fall 2011 23 projects regardless of any other reporting required. This form helps me in tracking my day-to-day activities or status of any and all weld procedure qualifications. Using or updating the form daily has proved essential to providing timely feedback to the client. Steven T. Snyder is technical manager, Oil States Industries (Asia) Pte Ltd.-Singapore. He is an AWS CWE, CSWIP-PAUT, ASNT Level III, ICC-S1 and S2, ASQ CQA with more than 23 years of multiple industry experience. Welding and Repair of Galvanized Coatings Robert Hay: The incorporation of zinc into weldments has a negative impact on the integrity of welds. This would include coatings at the fused surfaces of fillet welds as well as the groove faces of groove welds. Often there is no forethought given by fabricators in regard to the welding of surfaces with zinc coatings. All zinc coatings should be removed prior to welding as required in AWS D1.1, Structural Welding Code — Steel, Section 5.15 Preparation of Base Metal. The specific degree of zinc removal (i.e., distance from weld toe, removal of all intermetallic layers) should be thoroughly discussed with the inspection agency and welding contractor prior to welding operations. The WPS utilized on the project should address coatings and any surface preparation. Proper galvanized coating removal can be labor intensive and costly. Quite often, the removal and subsequent repairs are not anticipated while bidding projects. The repair of galvanized coatings is very important after welding operations have been completed. The CWI is often asked to review the zinc repairs although most have no formal training to do so. Improperly applied coatings can prematurely fail resulting in unprotected weldments. It is my experience that the performance of cold galvanized coatings is contingent on the quality of the surface preparation prior to application. The repair coating should meet the requirements of ASTM C780 for the repair of damaged hot dip galvanized coatings. It is critical the surfaces be free of oil, moisture, rust, dirt, or other contamination prior to application. Solvent cleaning (SSPC-SP1) is usually sufficient for new steel surfaces. However, surfaces that were repaired or welded might require wire brush cleaning (SSPC-SP2), power tool cleaning (SSPC-SP3), or commercial blast cleaning (SSPC-SP6) in order to remove all welding-associated problems that could compromise the coating. Some manufacturers require that a needle gun finish be performed (SSPS-SP11) on repaired surfaces. It is important that the coating manufacturer’s surface preparation and application instructions be followed. Robert Hay is a senior project executive for Flood Testing Labs, Chicago, Ill., the largest employer of CWIs in the state. His primary function at the company is as lead technical Table 2 — Sample Form Used on Projects
Inspection Trends - October 2011 - Fall
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