Comments on: Coating Options for High Strength Bolts http://www.portlandbolt.com/faqs/corrosion-resistant-options-for-high-strength-bolts Portland Bolt's Frequently Asked Questions Sun, 23 Oct 2011 10:20:33 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Dane McKinnon http://www.portlandbolt.com/faqs/corrosion-resistant-options-for-high-strength-bolts/comment-page-1#comment-2518 Dane McKinnon Tue, 04 Aug 2009 22:49:11 +0000 http://www.portlandbolt.com/faqs/?p=188#comment-2518 Your first question, is it appropriate to specify <a href="http://www.portlandbolt.com/faqs/corrosion-resistant-options-for-high-strength-bolts">ASTM F1136 Grade 3</a>, would be best answered by an engineer familiar with the coating and the application. I do not believe that F1136 has the same corrosion resistance properties as hot-dip galvanizing, I think that hot-dip galvanizing continues to be a superior coating, but it does have it’s drawbacks, such as a lack of smooth finish and some surface irregularities. Depending on the amount of corrosive forces at work in the application, F1136 may be sufficient, but it may not. Normally where I see F1136 specified is in applications with higher strength fasteners that cannot be hot-dip galvanized, such as ASTM A490 heavy hex bolts. The corrosion protection offered by F1136 in those cases would be superior to nothing at all. As for the thickness of both coatings, F1136 grade 3 specified a coating thickness of 0.24 - 0.47 mils, whereas hot dip galvanizing has a minimum of 1.7 mils, but can fall anywhere between that and 5.0 mils depending of the fastener and the galvanizer. Hot-dip galvanized hex nuts are therefore tapped oversize to accommodate the thick coating, whereas F1136 specifically states that the thread fit shall not be adversely affected. Your first question, is it appropriate to specify ASTM F1136 Grade 3, would be best answered by an engineer familiar with the coating and the application. I do not believe that F1136 has the same corrosion resistance properties as hot-dip galvanizing, I think that hot-dip galvanizing continues to be a superior coating, but it does have it’s drawbacks, such as a lack of smooth finish and some surface irregularities. Depending on the amount of corrosive forces at work in the application, F1136 may be sufficient, but it may not. Normally where I see F1136 specified is in applications with higher strength fasteners that cannot be hot-dip galvanized, such as ASTM A490 heavy hex bolts. The corrosion protection offered by F1136 in those cases would be superior to nothing at all.

As for the thickness of both coatings, F1136 grade 3 specified a coating thickness of 0.24 – 0.47 mils, whereas hot dip galvanizing has a minimum of 1.7 mils, but can fall anywhere between that and 5.0 mils depending of the fastener and the galvanizer. Hot-dip galvanized hex nuts are therefore tapped oversize to accommodate the thick coating, whereas F1136 specifically states that the thread fit shall not be adversely affected.

]]> By: Aaron http://www.portlandbolt.com/faqs/corrosion-resistant-options-for-high-strength-bolts/comment-page-1#comment-2516 Aaron Tue, 04 Aug 2009 18:51:45 +0000 http://www.portlandbolt.com/faqs/?p=188#comment-2516 Is it appropriate to specify "zinc/aluminum corrosion protective coating in accordance with ASTM F1136 Grade 3" for protecting a steel fastener in lieu of galvanizing? I am using A354 grade BC and need a smooth finish with minimal irregularities. would hot dip galvanizing be appropriate or the zinc/alum coating? also, what increase in member thickness should be anticipated with these protective applications? Thanks. Is it appropriate to specify “zinc/aluminum corrosion protective coating in accordance with ASTM F1136 Grade 3″ for protecting a steel fastener in lieu of galvanizing? I am using A354 grade BC and need a smooth finish with minimal irregularities. would hot dip galvanizing be appropriate or the zinc/alum coating? also, what increase in member thickness should be anticipated with these protective applications? Thanks.

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