Low silicon welding rods for galvaniz...

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Author Message David Axt, AIA, CCS, CSI Senior Member Username: david_axt Post Number: 1123 Registered: 03-2002 Posted on Thursday, September 23, 2010 - 05:14 pm:    Lately we have had problems with welds at exterior steel handrails telegraphing through the galvanizing. The contractor told us that the telegraphing happens with high silicon welding rods even if the welds are ground smooth. Has anyone had experience with this issue? J. Peter Jordan, CSI, CCS, AIA, LEED AP (Unregistered Guest) Unregistered guest Posted on Thursday, September 23, 2010 - 06:20 pm:    Is this the same contractor who told you that the code did not allow you to paint the electrical panels? (Unregistered Guest) Unregistered guest Posted on Thursday, September 23, 2010 - 06:26 pm:    Need some more information. What do you mean by "telegraphing"? What, exactly, is it that is "telegraphing" through the galvanizing? I understand this term to be used when referring to an aesthetic issue with paint, wood veneers, etc. I have never heard it used in the context you are using it. Is the weld hot dipped galvanized along with the rest of the railing - after fabrication? Or is the "galvanizing" you refer to actually a zinc-rich repair paint to cover up a weld done in the field? If the latter, then you need to change your spec to require that field repairs to welded galvanized steel be done with molten zinc to match the thickness of the original galvainzed coating - either with zinc solder or by metallizing. David Axt, AIA, CCS, CSI Senior Member Username: david_axt Post Number: 1124 Registered: 03-2002 Posted on Thursday, September 23, 2010 - 07:31 pm:    Peter - That was Wayne with the electrical panel question. Unregistered - What happens is that the galvanizing, for lack of a better word, "puffs" up at the weld due to the high silcon content in the welding rod. I found an article about this problem: http://www.galvanizeit.org/images/uploads/drGalv/silicon_welding.pdf Anne Whitacre, FCSI CCS Senior Member Username: awhitacre Post Number: 1018 Registered: 07-2002 Posted on Friday, September 24, 2010 - 11:00 am:    You don't really care what they use to weld the handrails; you care about what the final result looks like and how it performs. The welding material is entirely a contractor decision and if they make a bad decision, then they have to find a solution to it to get the specified result. Lisa Goodwin Robbins, RA, CCS, LEED ap Senior Member Username: lgoodrob Post Number: 91 Registered: 08-2004 Posted on Friday, September 24, 2010 - 11:39 am:    What about requiring compliance with NOMMA railing construction, like the following: Grind all joints flush and smooth so that joints are invisible after painting. Joint construction for steel railings shall comply with NOMMA standards for Type 3 Railing System Joint Construction, ornamental railing shall comply with Type 1 as directed by the Architect. (Unregistered Guest) Unregistered guest Posted on Friday, September 24, 2010 - 11:38 am:    I agree with Anne. The fabricator must be aware of what the appropriate welding rods should be to prevent this. I haven't seen this happen on our projects, so it clearly must be easy to accomplish. My opinion: the handrails should be reject and refabricated.