Paint in lieu of Galvanizing
Paint in lieu of Galvanizing
(OP)
Folks,
I am not a structural guy, but I have a structural problem of sorts. At an ongoing project, I received a call first thing this morning from the GC that "the steel arrived, but it isn't galvanized." By steel, he means about 250 feet of W21x73 to be used as a pipe bridge across a creek. The steel arrived with the red (zinc?) primer only. The specifications and drawings (prepared by others) clearly show the steel to be galvanized, but evidently the steel contractor "missed that part".
I'd love to tell him to send it back and get it right, but that won't fly with a two week turnaround time, so I need some alternative coatings that can be field applied. The steel will be exposed to the elements (not marine).
Any ideas?
Thanks.
I am not a structural guy, but I have a structural problem of sorts. At an ongoing project, I received a call first thing this morning from the GC that "the steel arrived, but it isn't galvanized." By steel, he means about 250 feet of W21x73 to be used as a pipe bridge across a creek. The steel arrived with the red (zinc?) primer only. The specifications and drawings (prepared by others) clearly show the steel to be galvanized, but evidently the steel contractor "missed that part".
I'd love to tell him to send it back and get it right, but that won't fly with a two week turnaround time, so I need some alternative coatings that can be field applied. The steel will be exposed to the elements (not marine).
Any ideas?
Thanks.






RE: Paint in lieu of Galvanizing
RE: Paint in lieu of Galvanizing
There are zinc rich steel coatings that are available.
I am unsure of their performance in the long term or compared to hot dip galvanizing.
Get the steel galvanized.
RE: Paint in lieu of Galvanizing
RE: Paint in lieu of Galvanizing
RE: Paint in lieu of Galvanizing
They should supply the correct specified material. Alternative coatings, approved by the EOR, can be considered, but these are high end coating systems.
Dik
RE: Paint in lieu of Galvanizing
Even though your schedule is tight, you're going to have to live with the structure for a long time. Don't let him (or her) use the schedule as a club to make a bad decision.
RE: Paint in lieu of Galvanizing
(i) probably means removing the existing primer by blasting
(ii) may be difficult to achieve in the field.
Galvanising may well be just as easy to obtain as a good paint system, and is the more robust solution.
RE: Paint in lieu of Galvanizing
If you want something resembling galvanizing, try metallizing. Again, you'll still need to blast off the shop primer, but spray metallizing is comparable to galvanizing in its ability to protect from corrosion over the long term.
Hg
Eng-Tips policies: FAQ731-376
RE: Paint in lieu of Galvanizing
The cost will be higher than painting, so expect resistance from the contractor if you choose to go that way.
RE: Paint in lieu of Galvanizing
If the structure is above a creek, it will be a little difficult to maintain a paint coating. And so, more than likely, it won't get done.
Painting is inferior to hot-dipped galvanizing. That is why you spec'd it in the first place.
Ask the owner if he is willing to accept painting, and if so, how much of a credit he want back for accepting an inferior product than the one specified in the contract documments.
If the owner does decide to accept a painted system, you will need to strip the primer paint off. Painting over the primer is a very bad system that likely will not hold up very long.
RE: Paint in lieu of Galvanizing
First of all, thank you very much for the responses - very informative and useful. The steel contractor has today taken the pieces back to the shop for sandblasting and galvanizing per the original specifications. I'm not sure exactly what the motivation was for this change of heart, but it has happened and I am back on track.
Thanks again for the advice.