# Cleaning ground flanges on aluminum enclosures



## Lone Crapshooter (Nov 8, 2008)

I am looking for a way to clean the ground flanges of explosion proof aluminum enclosures. The crust that forms between the flanges is almost impossible to get off. I am also wondering if it effects the venting of the enclosures.
Scotchbrite is extremely slow and not very effective I have seen razor blades used I would be afrade of scratches I have also scene Mobilux 2 red grease used to prevent the flanges from developing the crust. My own thought is to build a shed roof over the switch rack to prevent pounding rain damaging the joints. From what I have seen this problem effects enclosures that are exposed to direct rain.
Thanks for your time

LC


----------



## Peewee0413 (Oct 18, 2012)

Do you have a picture?

Sent from my SM-S908U using Tapatalk


----------



## Jlarson (Jun 28, 2009)

We usually go after them with a fine (white) 3m bristle disk. I usually use some flavor of silicone o-ring grease on the joints.


----------



## JRaef (Mar 23, 2009)

3M makes a marine Aluminum Restorer, I’ve used that in the past and it works pretty well. But I’ve also made my own with a 1:1 mixture of white vinegar and water. All you need is a slightly acidic solution, that’s the cheapest and easiest way to get it. The 3M stuff is I think nitric acid or something.


----------



## SWDweller (Dec 9, 2020)

"clean the ground flanges of explosion proof aluminum enclosures. The crust that forms between the flanges is almost impossible to get off. I am also wondering if it effects the venting of the enclosures. " Pretty sure you slipped your disco, or you have no idea of what you speak.

50 years I have never seen a vented explosion proof enclosure. Having a vent defeats the "no vapors escaping principal"

I have seen explosion proof enclosures installed in a lot of places, Rain was never a problem.
Now Al boxes and salt spray might be a different animal. Rain in most places is PH neutral.


----------



## CMP (Oct 30, 2019)

SWDweller said:


> 50 years I have never seen a vented explosion proof enclosure. Having a vent defeats the "no vapors escaping principal"



Every explosion proof enclosure has a vent, it must, or else it would b become shrapenal in the event that vapors inside became ignited.

The machined flanges that he is asking about cleaning, is the controlled pressure vent for internal explosion pressures. As well as every conduit and cover thread and tapped opening in the enclosure. No sealant is allowed on any of these vent openings so that the explosion pressures are not restricted.

The machined surfaces and threads are designed to have a specified finish with just enough roughness to allow explosive pressure and gas to escape, without letting out any flames or gasses that are hot enough to ignite any gasses that may be present in the surrounding atmosphere.

So yes, cleaning them with scrapers and risking putting scratches and groves in them is a dangerous proposition. Buffing discs on a grinder is also a bad idea. Best practice is to shield them from the weather and contaminates so that they don’t corrode in the first place.









The 'Ex d' type of protection: explosion-proof joints | Cortem S.p.A.







www.cortemgroup.com


----------



## Almost Retired (Sep 14, 2021)

SWDweller said:


> "clean the ground flanges of explosion proof aluminum enclosures. The crust that forms between the flanges is almost impossible to get off. I am also wondering if it effects the venting of the enclosures. " Pretty sure you slipped your disco, or you have no idea of what you speak.
> 
> 50 years I have never seen a vented explosion proof enclosure. Having a vent defeats the "no vapors escaping principal"
> 
> ...


This time it is you who is uninformed
as cmp has said they are all vented
you cant see it and dont know it but the flanges of the door/opening are machined to small tolerances that act as cmp said
even weather proof enclosures with a gasket are vented
the vapors are not meant to be contained, the fire of the explosion is all that is meant to be contained

*google it*


----------



## kb1jb1 (Nov 11, 2017)

Every weather rated hazardous location switch I have used came with a small tube of some type of oxide inhibitor that you applied to the mating surfaces. Once you have the pitting, or rust with the steel boxes, they no longer server their purpose.


----------



## glen1971 (Oct 10, 2012)

kb1jb1 said:


> Every weather rated hazardous location switch I have used came with a small tube of some type of oxide inhibitor that you applied to the mating surfaces. Once you have the pitting, or rust with the steel boxes, they no longer server their purpose.


I know the stuff you mean,but I haven't seen those tubes in years. I just replaced a couple of DSD switches and there was nothing in there. And no one I knew of carried any with them, to reapply after opening a door or cover.

To clean them, I've used a medium to fine 3M pad and time. I've never got one to factory finish, but I'm also inland so I doubt I'm dealing with anywhere near the same build up from salty air, that exists in many places.


----------



## CAUSA (Apr 3, 2013)

Be carful not to score or remove the surface material other than the build up of debris.

If it is erosion. And it is pitting. This changes the flame path/heat mitigation design. Check with the manufacturer and see what the tolerances are when assembled.They will have a procedure with a plastic gauge or a feeler gauge.

If the testing does fail the panel need to change. And the reason why two aluminum mating surfaced has started corrosion. Usually dissimilar metals that are wetted causing electrolysis is the culprit. Is the lid properly bonded internally?

here is a PDF of a manufacturer and their maintenance procedure.



https://hubbellcdn.com/installationmanuals/EXB%20IOM%20Sheet%20-%20General.pdf



This is good resource for the gap requirements. But consult with the manufacturer for the IP class that that panel is rated for.









Maximum Experimental Safe Gap


Maximum Experimental Safe Gap (MESG) Definition: (Ref: IEC 60079-1 ) Maximum Experimental Safe Gap (for an explosive mixture ) of a joint 25mm in width which prevents any transmission of an explosi…




expeltec.com


----------



## CAUSA (Apr 3, 2013)

I'm going to beat a dead horse here.
But some do not work on it a lot and it is for them. If it helps great.

Going to list what works for me in cleaning the flange and the reassembly of the enclosure.

I take a plastic gauge measure on 12 spots on the panel 4" in length. and record.
I examine the flange and note and indentations, scratches fault lines. Take photos if permitting allows.
- If there are dents/scratches, take measure of depth and report. Might be a show stopper depending on what's found and let customer know to make decision to proceed or not.

Remove all bolts with wood dowel.

If all good. check gasket condition. Can it be removed with out damaging it? if it can be damaged, I tape it with painters thick masking tape to preserve it. leave a 1/32/ to 1/16 edge on flange, both sides of gasket. (hard to do, but allows for reassembly and not wait for a replacement gasket).

Use a plastic scraper hard autobody grade to scrape all debris off flange. (I use a 12'long drywallers plaster blade to protect gasket if not removed).

Use a wood block and 500grite wet sand paper and oil to and flange to take the brail type debris down lightly. Then work to 1000grit. (yes time consuming around gasket area if still in place). Feel with ungloved fingertips, If I can still read brail then not good enough. (but not to make shinny) discoloration, I found is normal. depending on The age of enclosure, with the amount of flame path events.

The female bolt threads need to be cleaned and re-chased. The plastic bolt holder for the bolts to prevent them from falling out. Sometimes, over time-ageing/usage gets locked in to the threads and restricts the bolt reading in to the flange to create a good seal. Replace them or toss them (I let the customer decide 9 times out of 10 they are tossed).

Clean all debris from the bolts threading.

Re-measure the plastics gauge to see what the result is and recorded. If improved.

Install 3 to 4 desiccant packs to control internal sweating. in very corrosive internal conditions change the drain plug and breather vents.

Lubricate the flange with a thin layer of O-ring lube and reassemble in a flange multi bolt pattern sequence by hand (fingertips). This should be able to snug up and wipe away all excessive lubricant.


Then the standard commissioning procedures as per your work permit and JSA.


----------



## kb1jb1 (Nov 11, 2017)

glen1971 said:


> I know the stuff you mean,but I haven't seen those tubes in years. I just replaced a couple of DSD switches and there was nothing in there. And no one I knew of carried any with them, to reapply after opening a door or cover.
> 
> To clean them, I've used a medium to fine 3M pad and time. I've never got one to factory finish, but I'm also inland so I doubt I'm dealing with anywhere near the same build up from salty air, that exists in many places.


I think it was regular Penatrox


----------



## glen1971 (Oct 10, 2012)

kb1jb1 said:


> I think it was regular Penatrox


You could be right. I know on the bolts I always use a dab of STL.


----------



## Almost Retired (Sep 14, 2021)

glen1971 said:


> You could be right. I know on the bolts I always use a dab of STL.


that or penatrox
that stuff is hard to get off of your hands, it think it will stick better and last longer than stl


----------



## Lone Crapshooter (Nov 8, 2008)

I want to thank everyone for there replys. A lot of very good information here.
Thanks for your time
LC


----------

