| Author |
Message |
Brett M. Wilbur CSI, CCS, AIA
Senior Member
Username: brett
Post Number: 169
Registered: 12-2004
| | Posted on Thursday, May 07, 2009 - 12:25 pm: |    |
Here's an easy one, maybe. What kind of life expectancy can I assume for hot-dipped galvanized compared to stainless steel masonry wire-ties? Hospital project west of Houston, Texas. |
Christopher E. Grimm, CSI, CCS, LEED®-AP, MAI, RLA
Senior Member
Username: tsugaguy
Post Number: 202
Registered: 06-2005
| | Posted on Thursday, May 07, 2009 - 02:23 pm: | |
From our Hohmann & Bernard rep: Hot-dip Galvanized products are considered to be 40-50 year materials. Stainless steel is considered a 100 year material from our industry. Cost differential between the two products is considerable.
You might also want to check this out: http://www.galvanizeit.org, search for zinc coating life predictor. I thought there was a concise version of this somewhere that compared different designations of hot-dip with each other & with electroplated. Not sure where I saw that. It said how many years you lose between G90 and G60, for example. |
Christopher E. Grimm, CSI, CCS, LEED®-AP, MAI, RLA
Senior Member
Username: tsugaguy
Post Number: 203
Registered: 06-2005
| | Posted on Thursday, May 07, 2009 - 02:31 pm: | |
Yes, it depends on the thickness of the galvanizing, since it is a sacrificial layer. The table on page 2 is what I was thinking of: http://www.galvinfo.com/ginotes/GalvInfoNote_1_6.pdf.
Also you may want to be clear which type of stainless, not all are created equally. 300 Series (nonmagnetic) is more stainless than other so-called stainless (some may try to call 410 a stainless but it probably is not). Type 304 is frequently used. Type 316 may be needed if exposure to salt fog is a possibility - but this is inside a cavity, right? Still might be good due to exposure during construction. |
(Unregistered Guest)
Unregistered guest
| | Posted on Thursday, May 07, 2009 - 02:39 pm: | |
Type 300 will rust, type 304 & 316 will not. |
Curt Norton, CSI, CCS
Senior Member
Username: curtn
Post Number: 147
Registered: 06-2002
| | Posted on Thursday, May 07, 2009 - 02:47 pm: | |
Brett, one thing to keep in mind when making the decision between the two is the potential risk in case of a failure. For a two story application you can probably live with galvanized because it’s easily accessible if it fails in 50 years. If you are up 6 or 8 stories or more, the damage (or loss of life) from a failure would be much greater and it would be very expensive to repair. |
Mark Gilligan SE, CSI
Senior Member
Username: mark_gilligan
Post Number: 161
Registered: 10-2007
| | Posted on Thursday, May 07, 2009 - 06:25 pm: | |
When statements are made about life of a galvanized or stainless steel product what is often unsaid is what is the exposure. There is a difference between a building subject to salt spray from the ocean and one in Phoenix Arizona.
I would also be concerned about the possibility that different chemicals could impact galvanizing and zinc differently. |
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