Bucket Elevators: Painted, Sheet Metal or Hot-Dipped Galvanized Finish… What is Better?

 

Did you know Sudenga offers three different types of finishes on our bucket elevators? Painted, sheet metal galvanized and hot-dipped galvanized. When we offer these choices to the customer we are frequently asked, “What’s the difference?” Our response involves a conversation about what is important to the customer.

 

Painted Finish: 

Painted is often the lowest cost finish available. Sudenga’s standard painted color is blue enamel. (Custom colors, including white, gray, red and almond are available by request for a small additional fee.) The Sudenga paint process utilizes a wet electrostatic process that washes the fabricated component, primes, and then covers the part with two coats of wet polyurethane paint that then goes through an oven to bake it all on. This provides a finish that covers well and is durable and attractive. Paint can have a shorter life than galvanized finishes however, so it may be necessary to repaint a painted finish leg for cosmetic reasons before it wears out mechanically.


Sheet Metal Galvanized Finish: 

A sheet metal galvanized finish on your bucket elevator is a cost-effective way to get many of the benefits of a galvanized finish, without the extra steps of sending the fabricated components out to be hot-dip galvanized.  Essentially, the elevator leg is fabricated at the factory out of pre-galvanized material.

Inevitably subassemblies need to be welded together. Things like leg trunking flanges, or inspection doors are almost always welded on. In the case of sheet metal galvanized fabrication, the welding process burns off the pre-galvanized finish in the area of the weld, which later needs to be painted over in that area with a zinc rich paint.  Zinc rich paint coats the surface of the weld, but does not chemically bond to the weld/metal like a hot-dipped galvanized finish. This is an area one may see rust in the long term because this paint, though rich in zinc, doesn’t weather as well as the integrated galvanizing. 

To avoid the hassle of welding, then touching up galvanized material, often manufacturers will choose to bolt or rivet subassemblies together as much as possible. This mechanical fastener type connection is relatively quick and easy for the manufacturer, but is typically considered lesser quality than a welded seam when it comes to elevator leg construction methods. Welding a seam often seals up a crack in a connection point that would be open in the case of a mechanical fastener connection. Dust can settle into that mechanically fastened seam, wicking in moisture that eventually can contribute to corrosion of the metal at that point. 


Hot-Dipped Galvanized Finish: 

Hot-dipped galvanized finish is often slightly more expensive than a sheet metal galvanized finish, but the tradeoff is worth considering as the benefits are numerous. With the hot-dipped galvanized finish choice, the components of the elevator leg are fabricated and welded, then sent off to be dipped in molten zinc. (Molten zinc makes up the galvanized coating.) Dipping the parts after they are fabricated essentially seals up all welds, and coats everything, inside and out, in a thick coating of zinc. The steel in hot-dipped components forms a chemical bond with the zinc. This coating ensures that any scratch or ding that might get to bare metal is protected, as the properties of the zinc finish around the scratch “sacrifices” itself over time. This essentially seals the scrape off, not allowing the damage to rust or grow further.  It should be noted that because fabricated components are dipped into a bath of very hot molten zinc, it is not uncommon for lighter gauges of steel to develop a slight wave on the larger flat faces of some leg trunking sections. This is generally cosmetic only and Sudenga’s hot-dipped legs are designed and quality checked prior to shipping with this possibility in mind.  It is wise however, to make end customers aware of this characteristic so they can decide if the long term-durability of a hot-dipped finish is more important than any subtle cosmetic concerns.


Ultimately, Sudenga Bucket Elevators are offered in these three finishes because every buyer and application is different. Let what is most important to you drive this decision. The choice is yours.

 

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