Corrosion of Exposed Structural Steel

[StructTaco]

I have anchors for a large zipline that were specified to be galvanized. The contractor didn't do it, and now I'm at a loss as to how to protect things against corrosion without disassembling everything. See picture attached.

Any ideas, the AISC code states that if it's exposed, it must be protected against corrosion. Is galvanizing required, will painting the exposed surfaces only provide that protection?

Thanks for any help

 

[dik]

Do the, what appears to be Dywidag threadbars, form the ziplines? These do not appear to be coated and should be; is this the problem? It is possible to clean and coat these with a zinc rich primer, but is a shorter term solution to HDG. Can the threadbar be replaced one at a time (low loading cycle) with a proper HDG bar? The replacement bar can be on site and replaced quickly.

Because of the small cross sectional area, the threadbars should be coated ASAP.

If the problem is the anchorage itself, a spare one can be made and HDG. Possibly during a low loading cycle, this can replace the existing.

I'm not sure if I answered your query.

Dik

 

[CoryPad]

As dik mentioned, there are zinc-rich coatings that can be applied in the field that are alternatives to hot dip galvanizing. They usually have less zinc, so the lifetime is shorter, but that is a maintenance and inspection issue now. There are multiple manufacturers of these coatings, including PPG and Carboline.

 

[kelowna]

Paint is a valid option.

It will not provide the same level of protection as hot dip galvanization and it will require adequate maintenance, but a good paint system is suficient for most conditions.

 

[unclesyd]

I was recently an observer on a similar situation that was resolved by the method presented by dik to everyone's satisfaction except the contractor.

Just make sure you have the proper nuts for the HDG bar.

 

[EdStainless]

The only problem is that to properly paint them they will need to be dismantled and preped (blasted and washed). If you are doing that then replacing them with HDG isn't much more effort.
If you paint them you will need need to inspect and repair the coating regularly.

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Plymouth Tube

 

[StructTaco]

thanks everyone, the client is asking me to relax the requirements, just looking for options, maintenance will definitely be increased, at this point we can't get to the unexposed surfaces adequately, but I can require that they change them out later.

 

[hokie66]

You asked this question previously, and the answers are pretty much the same. It is the contractor's problem, and the client should not expect you to relax critical requirements. My assumption would be that maintenance will NOT be adequate.

 

[StructTaco]

you are correct Hokie66. unfortunately the contractor and the client are partners in this project. I will have them maintain it and then replace when feasible, that's all I can do without getting into a legal battle at this point.

 

[hokie66]

Fair enough. I would go one step further, i.e. put my concerns in writing to the client. But the problem with this approach is that the property could change hands, in which case a new owner would be stuck with a substandard construction.

 

[StructTaco]

I put it in the drawings in a plan change I'm going to get approved this morning, and wrote it to the client. Thanks again.

 

[unclesyd]

Every Engineer should have a CMA plan in his repertory.

 

[StructTaco]

definitely