Check out this company - perhaps you can get some info from the site or from calling them directly.

http://www.abchance.com/

 

screw piles (or helical piles) are typically galvanised. painting is not approriate as it gets scratched during the installation process.

It is then just a matter of specifying a sufficient thickness of galvanising for the application.
 

About eight years ago I had one screw pile job for a large manufacturing building - on old fill that was too deep to over-excavate economically.

The performance of the building is fine with the piles.  The problem we ran into was the lack of contractors who were familiar with and had the special installation equipment for this type of pile system.  It does require specialized, non-standard equipment.  We were at the mercy of the contractor's schedule as he was the only one for MILES around who could do the job, and he knew it.  This drove the price up, and the extended the building erection timeframe.  There were hard feelings between the pile contractor and the owner before the end of the job.  

Just something to think about.  Personally, I will not use screw pile again unless there are muiltiple contractors who are available to bid.  Goodd luck.

Mike McCann
MMC Engineering

thanks for your useful info, we might also a have a problem on finding several contractors who can do screwpiling but 2 or 3 bidders will make the bidding successful. We are considering this as alternative to micropiling, this method is clean and will not generate too much water/mud coming out of boreholes and limited headroom will not be a problem compared to other methods. Piling will be done inside an existing building while plant the operating.

Another option is jacked pipe.