Perpetual screw piles. Do I need to overpay for a hot-dip galvanized coating?

In the first part: Five ways to make screw piles last forever I touched on the ways to protect screw piles, which small young companies will not talk about. I propose to dwell in more detail on one method of protection: hot-dip galvanized.

It is called hot for the reason that steel products (in our case, screw piles) are lowered into a bath of molten zinc. The temperature of molten zinc is 420-450 g. and he covers the steel with a thin layer. Zinc is more resistant to oxidation and protects for a long time screw pile even in soil with a high level of groundwater, in a swampy area, near the shore of a reservoir (pier). In such places this additional protection is needed. Watch the hot dip galvanizing process at one of the screw pile companies:

In order for zinc to penetrate inside screw pile, a hole is drilled in the lower part of it and when immersed, liquid metal penetrates inside (no air seal is created in the pipe), evenly covers the product both inside and outside:

The method of cold galvanizing is, in most cases, painting with zinc-containing paints. The coating is not resistant to damage during pile tightening. There is a technology for electroplating, but the technology is not used in the production of screw piles, the process is too long.

The most important question for many customers is the cost of galvanized piles. Prices:

Why is the cost so much higher than uncovered? Piles need to be prepared - cleaned of oxides, dirt. These are processes of sandblasting, then degreasing (heating and processing with reagents), washing and drying. At all these stages of preparation, specialized equipment is involved, consumables are needed (including zinc), the time of shop workers (qualified and experienced specialists).

There is a compromise in additional protection of screw piles:

The heat-shrinkable tube is not put on the entire length of the screw pile, but only in the place where it comes out of the ground, because it is at the ground level that there is constant moisture and the highest oxygen content. The tube protects against lateral moisture from the ground, but condensation can accumulate under it or moisture can rise under the tube. The process of rust formation, of course, will go much slower, but it will not stop at all.

What happens if we add electrocorrosion to the oxidative process? Zinc also interferes with this process.

Inside screw piles without zinc coating, it is necessary to pour concrete or dry sand-cement mixture, which takes moisture from the condensate onto itself, turning into concrete.

A comparison of the resistance of protective coatings (anti-corrosion painting and hot-dip galvanizing) can be seen in the video:

In the video, the oxidation process is accelerated as much as possible with hot water, salt and hydroperite (which releases oxygen in water).

By using galvanized products, you are guaranteed to extend the service life of your pile field up to 100-120 years, which is comparable to the life of a house. And whether you need to overpay for this - decide for yourself.