Galvanized steel pole protection from rust

[robyengIT]

In Italy we have a lot of steel poles (hot galvanized) used for tele-transmissions. Many of them have been built few years ago and now they need to be reinforced/stiffened due to more severe loads (fig 1). We would like to use stiffening steel structures connected to the original pole (circular/octagonal section) by means of “hollobolts – blindbolts – box bolts” or similar (fig 2 + video). The different Authorities don’t like because of rusty problems that the drilled holes can cause (if any). They would like to use only stiffening structures with clamps (fig 3). Anyone has field experience in such a problem? Any help/suggestion is welcome. Thks

https://www.youtube.com/watch?v=ZqCrHP9MNSo&t=8s

 

[dauwerda]

Steel poles are used all over the US where holes are field drilled to accept hardware (wood pole equivalents).

It is best practice to repair the coating on the exposed bare metal with zinc rich paint (cold galv) or Zinc-Based Solders (hot stick).
It is also worth noting that any bare metal that might be left exposed will still be protected through cathodic action from the zinc on the hardware passing through the hole (as well as the zinc still in place surrounding the hole.

All this to say, you should be able to use hollow bolts without causing any detrimental effects to the corrosion protection of the poles.

 

[MotorCity]

I know field welding can get expensive (especially when its galvanized) but I think you would benefit more by welding steel plates or angles to the poles rather than bolting.
For the bolted pieces to strengthen the pole, they would have to be perfectly attached and work compositely. Any slip of the bolts in the holes would add no or minimal strength. You would just be adding dead weight to the pole. I think the even bigger concern is corrosion. In general, I try to avoid drill holes or cutting openings into tubes, poles, or pipes exposed to weather. Can it be done? Sure. WILL it be done correctly....I seriously doubt it.