Over a period of time I noticed that one of my radio masts (Ex Wind Turbine Mast) was showing signs of rust where two pipes were welded together. Both the pipes, one 100 mm and the other 38 mm are fully galvanized except where I welded the two together about 15 years ago. Unfortunately I did not take a photo of the rusted area where I welded the two pipes, before starting the maintenance.
Now why on earth would I compile this posting of the maintenance. Let me explain. 15 years ago I painted the welded areas with the following coatings after cleaning the areas thoroughly:
1. Liquid Thinners after grinding and sanding the welded area.
2. NS 1 Rust Buster ("White Milk" Rust Converter and Primer)
3. NS 5 Metcote Etch Primer ("Rooi Lood")
4. Silver Aluminum Paint (2 coats)
5. Transparent Rust Protector Spray
With all the above layers of protection the rusting process was slowed down for at least 15 years. After taking off most of the rusted flakes I was quite surprised to find that the rust was not so severe and that the area should last another 15 years after painting the area again with the above products.
I had another trick up my sleeve to further protect and hopefully curb maintenance for the next 18 years. I decided to put a cover over the welded area preventing rain and sea spray from directly making contact with the metal surface areas that's not galvanized. In the olden days a VW Beatle rubber drive shaft boot did the trick but unfortunately did not last long as the sun caused the boot to perish after a few years.
I used a PETG UV protected bottle and made a cover hat. Ordinary 2 liter PETG bottles last fairly long in direct sunlight. Time will tell how long this protective cover hat will last and if it would protect the welded area better. Galvanizing the welded area is really not an option as you must arrange transport to George and you pay per kilogram for galvanizing. Both pipes and the welded area must be hot-dipped. At R32.00 per kg this would cost more that the two pipes. Cold galvanizing was another option but at R847.00 a liter and the fact that it dries up in the tin quite quickly, did not make it a viable option.
I could have used my hot air gun to shrink the PETG cover hat tight against the two poles but I was afraid that dampness might be trapped between the pipe and cover due to condensation./dew. I decided to leave it open at the bottom. See images.
Finally: I repainted both poles with Silver Aluminum Paint as I did before and hopefully it will last for the next 15 - 18 years. It is important at the sea to maintain radio masts and galvanized towers on a yearly basis. Galvanizing also needs maintenance especially moving parts. Transparent Rust Protector Spray is used for this purpose. I trust that this article will be of benefit to those who is not familiar with rust and maintenance of a mast/pole/tower erected in a coastal area.
Images: Click on images for larger view.
