CoatingsPro Magazine

JUL 2016

CoatingsPro offers an in-depth look at coatings based on case studies, successful business operation, new products, industry news, and the safe and profitable use of coatings and equipment.

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COATINGSPRO JULY 2016 57 mist coat is then applied to "seal " the porosity within the inorganic zinc coat that allows the bubbles to form before any full wet coats of the material. If, during application, pinholes are observed forming, stop and look at the application process and determine what needs to be changed to prevent the pinholes. It's much easier in the long run to correct the process than to correct the resulting pinholes. Te challenge to the project team — owner, engineer, inspector, coatings manufacturer, and coatings applicator — is to look at the installed materials and the frequency of the defect to determine if corrective action is necessary or if the infrequent defects really pose a problem. Do the pinhole problems signifcantly outweigh the consequences performing corrective action? Ultimately, the point of this discussion is not to create a trend of accepting work that is sub-standard but to frst understand the defect and do everything possible to avoid it. Ten, be reasonable when evaluating infre- quent and minor cosmetic defects with little or no consequence to the coating's intended performance and to move the project forward. CP D. Terry Greenfield is a pr incipa l consu ltant w it h Cor roMet r ics Ser v ices, Inc. Greenf ield has more t han 37 years' e x per ience in t he protect ive coat ings and cor rosion indust r y, prov id ing prog ram and project management, qua l it y assurance, cond it ion assessment and ma intenance planning , specif icat ion development, fa i lure ana lysis, e x per t w it ness, and t ra ining for t he mar ine, t ranspor ta- t ion, oi l and gas, and ot her indust r ies. Greenf ield is a g raduate of t he Universit y of Cent ra l Flor id a. He is a NACE Level III Coat ing Inspector w it h Br idge, Mar ine, and Nuc lear Specia lt ies. He hold s Of fshore and Shipboard Cor rosion A ssessment Technician cer t if icat ions, and he is a Societ y for Protect ive Coat ings (SSPC) Cer t if ied Protect ive Coat ings Specia l ist. For more infor mat ion, contact: Cor roMet r ics Ser v ices, Inc., (251) 4 45-1560, w w w.cor romet r ics.com Photo 4. Failure to properly seal the inorganic zinc surface with a mist coat will result in extensive pinholes after application of the intermediate coat. The bubbling created from the trapped air without sealing the inorganic zinc porosity will definitely result in a situation similar to the one pictured. The challenge to the project team — owner, engineer, inspector, coatings manufacturer, and coatings applicator — is to look at the installed materials and the frequency of the defect to determine if corrective action is necessary or if the infrequent defects really pose a problem. Photo 3. If this were a three-coat system (inorganic zinc, epoxy, urethane) in atmospheric service and pinholes such as these were isolated and limited in frequency, there could be a reasonable argument for acceptance. Pinholes Wr i te in Re ad e r In q u ir y #222

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