Letter 27075

Surface profile of Galvannealed steel  

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We building industrial buildings and we use Galvannealed steel for our walls. Well, a customer has provided us w/ a spec. calling for the walls to meet and/or exceed the requirements of SSPC-SP7. SP7 is a blast cleaning. I am trying to prove that there is no need to blast a galvannealed surface. Do you have any documentation for the profile of galvannealed? Or any ideas of how to prove this point?

Jody Grimes
Project Mgr. - Houston, Texas, USA

By the time you blast a galvanneal coating to SSPC-7 there will not be any zinc left on the part. If you look at a galvanneal coating cross section under a microscope you are getting a comparable surface to SSPC-7 anyway. For a hot dip galvanized coating (much thicker)an sspc-7 would be fine.

Mike Stroia
Galvanizing - Canton, OH USA

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