Weathering Steel vs HDG 4

[ldeem]

I work in mining and am in the process of designing a replacement 90' truss. This is a limestone facility and the truss will be part of material handling system. Corrosion is a significant problem at the site. In the past we have used a lot of HDG but that can be hard to do on larger trusses, not to mention costly.

I was thinking of looking at weathering steel as an option. I have seen it used on some heat exchanger hoppers and it has held up relatively well.

I am looking into the price difference now but my question is if anyone has used weathering steel in a similar situation and has it stood up over time? This location gets a lot of material buildup (limestone fines) which tends to build up and would trap moisture. I understand weathering steel doesn't perform well in that situation.

 

[dig1]

Ideem,

We do a lot of work in mining and waste-to-energy (WTE) plants. The ash is generally stabilized with lime and is wet and hangs to everything. Our experience is that, in general, a properly specified and applied 3-coat paint system holds up very well. HDG does not hold up more than a few years in the WTE environment. Also, we use a lot of HSS to avoid spots for the material to collect, no double angles (WTs instead)(a lot of "rust jacking problems with the 2x angles). GC_Hopi brings up great points regarding detailing.

This has been the most economical life cycle approach and the coatings are holding up well (10+ years). One of the key areas is field painting the hardware as this is one of the first areas to see problems if not done properly.

 

[PersonalProfile]

I cannot directly assist, though the following may be of interest, despite that you may be aware etc:

Quicklime (calcium oxide) is a widely used chemical compound used for mixing mortar, acting as a flux in smelting processes, and treating wastewater. When dry, quicklime is not excessively corrosive to galvanized steel, but when it combines with water it creates calcium hydroxide, which is extremely corrosive to galvanized steel. In addition, the reaction of quicklime with water is an exothermic reaction (meaning it releases heat), which will further add to the corrosion of the galvanized coating.

https://galvanizeit.org/knowledgebase/article/corrosive-chemicals-and-galvanizing

 

[dik]

American Galvanisers' Association is a great source... They have a lot of free webinars, too.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[dik]

I seem to recall the problem is a little trickier... if I recall, quicklime is slightly hygroscopic, and attracts moisture from the surrounding air...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik