Electrical equipment enclosures
Electrical equipment enclosures
(OP)
Cut me some slack because I'm an EE, but in Hawaii, when specifying outdoor equipment enclosures for DoD land-based projects, we call for 304L or, preferably, 316 stainless steel. High humidity and chlorides quickly corrode other steels, supposedly 304 stainless too.
Three issues:
[1] Equipment manufacturers are generally reluctant to provide the preferred 316 stainless enclosures because the material is brittle and hard to work. Is this a valid excuse?
[2] Is 316 stainless suitable for hardware (bolts, nuts, etc) due to its brittle nature e.g., if subjected to vibration?
[3] Is 304L more impervious to chloride corrosion than 304?
Due to one or more of these concerns our clients end up with 304L stainless enclosures and hardware, which, according to my reading, is more vulnerable to corrosion from chlorides than 316 .
An equipment manufacturer I recently consulted said his company will only provide 305 stainless steel for use in Hawaii. Would this be a better option?
Would appreciate any advice you can offer.
Three issues:
[1] Equipment manufacturers are generally reluctant to provide the preferred 316 stainless enclosures because the material is brittle and hard to work. Is this a valid excuse?
[2] Is 316 stainless suitable for hardware (bolts, nuts, etc) due to its brittle nature e.g., if subjected to vibration?
[3] Is 304L more impervious to chloride corrosion than 304?
Due to one or more of these concerns our clients end up with 304L stainless enclosures and hardware, which, according to my reading, is more vulnerable to corrosion from chlorides than 316 .
An equipment manufacturer I recently consulted said his company will only provide 305 stainless steel for use in Hawaii. Would this be a better option?
Would appreciate any advice you can offer.





RE: Electrical equipment enclosures
[2] Type 316 is a very common grade for stainless steel fasteners. It can be cold worked (forged) or machined.
[3] 304L has essentially the same corrosion resistance in chlorides as 304. The others can provide more specific info.
Regarding 305, this is typically used in bar or wire applications, since the increased Ni content vs. 304 (10-13 vs. 8-10 reduces the amount of work hardening during forming/forging. The Ni content does not confer much improvement in chloride resistance. Mo is the key here, and 316 with ~ 2% Mo is the minimum you should be using in outdoor environments. A duplex alloy like 2205 may also be an option. Others will be along shortly with more advice...
RE: Electrical equipment enclosures
Have a look at the Nickel Institute Development web site www.nidi.org they have some information on this. Or the Australian Stainless Steel Development have www.assda.asn.au performed some very good work on use of stainless steels in costal environments. Particularly in relatin to tea staining.
Regards
Mark Hutton
hutton4eng@picknowl.com.au
RE: Electrical equipment enclosures
Their old standard, #4 polished 304, began showing slight corrosion in coastal installations as service stations went to covered pumping areas, which was unacceptable. They tried polished 316 unsuccessfully and had even tried to get 317, when we suggested they try a bright annealed 304 which had a imprinted finish to resemble #4 polish. All corrosion problems were eliminated. We had had equal success with commercial kitchen equipment in such environmeents previously.
The key was the surface finish rather than the grade per se. When we talked to the outdoor electrical enclosure people, we had no luck gettin them to budge from their #4 polish which suited their shop practices of grinding welds.
It sounds like they still haven't figured it out. If they won't listen to their customers or their suppliers, I don't know how to get through to them.
RE: Electrical equipment enclosures
According to the ASSDA research surface finish is certainlly the key to surface corrosion.
Mark Hutton
hutton4eng@picknowl.com.au
RE: Electrical equipment enclosures
Check these links:
http://www.rittal.com
http://www.hoffmanonline.com/
http://
John
RE: Electrical equipment enclosures
They aren't as pretty, but work much better.
The smeared metal from the polish form crevices that trap impurities and are locations for easy initiation of corrosion.
When it comes to resisting chloride pitting you need to look at the Cr and Mo content of the alloy. And to be honest, the Nitrogen also. For austenitic stainless grades the formula that correlates with crevice corrosion resistance is roughly Cr + 3.3xMo + 16xN.
At todays prices a lean duplex grade like 2003 or 2101 would give as much corrosion resistance as 316, higher strength and lower cost.
= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.
http://www.trenttube.com/Trent/tech_form.htm
RE: Electrical equipment enclosures
Is there a data sheet on 2101 on the web? I know Allegheny publishes a blue sheet on 2003.
RE: Electrical equipment enclosures
http://www.outokumpu.com/20257.epibrw
Try this, I have asked for some additional tech data and it has been very slow in coming.
There is also the older 2304. Very good for caustic service, but not of any great general interest.
AK makes 19D. I don't care for it.
= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.
http://www.trenttube.com/Trent/tech_form.htm
RE: Electrical equipment enclosures
RE: Electrical equipment enclosures
Everyone is selling something and we need people with knowledge to share. Thanks for the input.
Mike McGuire
Michael McGuire
http://stainlesssteelforengineers.blogspot.com/