Hose down of electrical equipment exposed to salt water 3

[buddy91082]

Hi there. We have some damaged electrcial equipment that was exposed to saltwater. We have been hearing from contrators that the best way to handle this is to hose down the equipemnt (deenergize, take out all breakers, and leave bus bars exposed and hosedown the bus bars and interior gutter). The dry out with heaters. Then megger test the bus bars and replace all breakers with new.

Anyone have experince with this?

Thanks.
b

 

[sibeen]

I've had a few similar experiences over the years. In my opinion you're probably better off to replace the equipment. A cheap repair can cost any organistation a lot of money down the track.

 

[DTR2011]

Please see the FAQ about this

 

[rasevskii]

This sounds like a hurricane Sandy issue. IN principle any electrical equipment immersed in saltwater is more or less ruined depanding on how long it was submerged, in part. There will be corrosion and rusting very quickly after the equipment is dewatered. Hosing down busbars and channels with freshwater as suggested and dryout and meggering is a last resort if there is no replacement available. Control and protection, electronics, breakers, and relays have to be considered to be basically destroyed.

As a temporary measure, something can be lashed up with available material to get service back and running, until replacement equipmaent can be delivered. It will be a legal and guarantee issue if a contractor installs something temporary that restores service relatively fast, or if he waits for delivery of new equipment so that a guaranteed installation is done according to all codes.

It is a war zone, electrically speaking. Do a lash-up or a hose-down and be liable, or do a proper job according to code and be safe.

I think few contractors would go for the temporary option.

rasevskii

 

[dpc]

I'd start with the NEMA guidelines linked in the FAQ. Molded case circuit breakers should probably be replaced. Anything with electronics should be replaced. The panelboard and switchboards themselves may be salvageable as your contractor is suggesting. Dry-type transformers, unless encapsulated, should be replaced. Hosing down circuit breakers is probably going to create a lot of problems down the line. Of course this is easy for us to say - in reality trying to source replacement equipment could be a long process. I'd check with the major US suppliers - GE, Eaton, Square D. I'm sure they are geared up by now to respond to requests for new equipment.

When space is at a premium in downtown areas, there is a strong temptation to push all of the main electrical distribution equipment down below grade. This is always a mistake. Keep electrical equipment above the 100 year flood elevation - not 100% guarantee, but a good starting point.

Good luck to you.

 

[rasevskii]

@buddy91082:

You dont say what voltage level you are dealing with. Even if it is 120/208 or 480V not any higher voltage, the remarks of myself and dpc still apply. The NEMA document does not specifically mention saltwater, only floodwater or contaminated water. Now after Sandy they may have to rewrite it with much harder advice for saltwater.

Many building owners in NYC may have to accept a tradeoff: A temporary fix (without guarantees) for now, to be replaced with new at a later time.

rasevskii

 

[oldfieldguy]

Yes, washing down with fresh clean water will be a step toward remediation. However, some gear makes it very difficult to get to the bus bars and insulators. GE's PowerVac line comes to mind, and you really want to be able to wash and wipe down insulators lest you leave a coating of residue that leads to tracking.

Also you need to keep in mind that switchgear has a lot of nooks and crevices that are not part of the insulating system. These will likely retain salt residue and begin rusting at an advanced rate.

Remediate what you must, replace components as advised above, but be looking at replacement in the short to mid-term future.

I've been through this with multiple hurricanes down here, as well as a few other disasters like a failed storage tank at a paper mill that flooded an MCC with 'black liquor' and a petrochem plant that burst a muriatic acid line that ate through a cinderblock wall and got into some medium voltage gear. We were able to get the two chemical disasters up and running pretty fast, but with that "Get the new stuff on order, we can't guarantee this one for too long" caveat.

old field guy

 

[cranky108]

Washing and wiping insulators is a reied and true way of cleaning insulators. However anyone who knows about salt, knows steel will corrode very quickly.
The exact type of equipment wasen't stated, so it has been assumed insulators and metal boxes. Different materials respond differently to this type of event. A little more specifics might help with more answers.

 

[rasevskii]

In Manhattan, where numerous basements have flooded with saltwater, only now still being pumped out, many buildings have been already declared Unsafe or Uninhabitable, because there is no power, heat, elevators or water supply. This is according to the Curbed NY website. Some very high-end condo bldgs are affected by this. Tenants have been served with a notice to move out. Even so, they must still pay the rent.

Even when Con Ed restores power to a given neighborhood, the bldg owner still has to inspect the electrics, water pumps, heating system, etc, before services can be restored. We know that practically everything electrical will have to be replaced. Only then can the tenants move back in. Time periods of several weeks are mentioned.

BTW the water supply pressure in Manhattan from the city is only adequate for a 6 floor bldg. Therefore water pumps in the basements are standard for higher buildings. I know, I used to work there.

rasevskii

 

[buddy91082]

Thanks for all of the helpful responses. And yes, this is a Sandy related incident and equipment in question is 600v and less.

b

 

[DTR2011]

Well now that we know a little bit more about the situation a few more suggestions.

Given the emergency nature of the situation, we can assume you need to energize equipment for a temporary situation. A reasonable plan should be put together that ultimately addresses replacement of the affected equipment in a timely fashion.

What does the AHJ have to say? What does your insurance company have to say? Who is the property owner and what do they have to say?

From the NEMA publication, "Items Which May Possibly Be Reconditioned by Trained Personnel in Consultation with
Manufacturer:", does your contractor have the approved training and consultation with the OEM? Will waivers be given?

Some other things you may encounter which is who owns what. Assuming you may be dealing with multiple vendors over multiple decades makes tacking down who is who a bit of a nightmare.

It may also be useful to check the used market for equipment.

 

[gattie]

An old Boss's expression:"Perfection is not of this World" comes to mind when Engineers & their crews have to deal with a painful situation like Sandy's aftermath.
Time is of the essence to get heating & lighting restored for the millions of suffering citizens.
Safety is always a major consideration at times like these, but should not entirely hobble Engineers from using some lateral innovative thinking to restore some speedy, albeit, temporary comfort, for the victims.
Where is “Marmaduke Surfaceblow when we need him?
Washing & drying of flooded electrical equipment has been a method used successfully many times.
How did Engineers handle The WW2 blitz of London, Pearl Harbour & New Orleans?
Stephen Michael Elonka ( - 1983) was the author of numerous technical books, including Standard Plant Operators' Manual.[1] He also wrote a book of the adventures of one Marmaduke Surfaceblow, a fictional engineer who solves difficult problems in ingeniously simple ways.[2] POWER Magazine's Marmaduke Awards were named for this character.[3]

 

[cranky108]

For 600V and lower gear, if I recall correctly, the circuit breakers in many cases have a circuit board inside (at least for GFCI, and ACI). those probally have to be recolaced. the box cleaning will depend on how damaged they are, but a good wipedown of the non-conductive parts is a must.

At a minimum you have accelerated the ageing of equipment. At the most you may have to replace it.

One problem is rust tends to takeup more space than non-rusted steel, so alignments that have been desturbed may not work right.

 

[rasevskii]

@gattie:

Yes but in todays litigious world, anything that goes wrong with a temporary lashup or a hose-down, or an electrical accident that has resulted from a non-code installation may well result in a lawsuit for 7-figure damages. We are not in wartime and abroad in some remote third world battleground. The power company will possibly simply not energize anything that is not approvable. They would have much to lose as well as the building owners. And what would insurance inspectors have to say...

The days of the likes of Marmaaduke Surfaceblow are long gone, regrettably. In those times there was no OSHA or swarms of Lawyers looking for more business...

I agree with smallgreek...what can be approved and not approved, has to be agreed beforehand in each situation, "in writing" I might add.

rasevskii

 

[itsmoked]

A great many circuit boards won't care a bit if they get submerged - as long as they weren't energized during or after. Pull them out marking all connections clearly. Wash them in a stream of warm water with a few drops of dish soap. Use a toothbrush where ever you want. Blow them off with about 50psi. If you can't blow them off, you need to final-rinse them with very low mineral water like RO water, DI water, or distilled water. Shake them off as best you can and stand them on a single corner if possible. Let them air dry for 24hrs or under forced air flow for several hours. Alternatively place them in an oven set to about 140F/60C. If the boards have wrapped coils you need to oven them for about 24hrs. If they have push buttons or switches they may be unreliable. Sometimes switches can be resurrected by forcing compressed air into some seam for 10~20seconds.

Most people don't realize that a lot of assembled circuit boards get run thru dishwashers during production.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[HowDidYouBreakThat]

Most people don't realize that a lot of assembled circuit boards get run thru dishwashers during production.

Sorry for the sidetrack. My dad told me that when he worked at General Dynamics, they used an ordinary household dishwasher to clean flux from circuit boards. Most of these boards were worth over $100k each.

Terry
KI6FCI

 

[itsmoked]

I wouldn't call them "ordinary". They always seemed to pick the "premium" stainless steel models.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[HowDidYouBreakThat]

Nothing but the best!

Terry
KI6FCI

 

[jraef]

I had to re-commission some 2300V VFDs after they were flooded by a mixture of storm/sea/sewer water. That's exactly what we did, took the PCBs out and ran them through a regular dishwasher to get all the contamination off, then I rinsed them in deionized water one last time before blow drying them. We also did hose down the power structure with fresh water after removing everything removable and went through the recommended drying procedure. But we scrapped and replaced anything that was not encapsulated or could not be effectively opened up and cleaned out, such as circuit breakers, small relays, control power transformers etc. The drives worked fine after we got done. When I left Seattle in 1997, they were still running after about 5 years from when we did the rebuild. Don't know if they still are, but most likely that would be because of a change in technology (these were old Robicon Current Source Inverters and are no longer made or supported).

The thing is, that was a LOT of effort, but we were salvaging 2 VFDs that at that time were worth a half million dollars, so it was worth it. Some 600V switchboards? Not likely in my opinion to be worth the effort compared to replacement other than to buy some time to get replacements, which from what I've heard is already getting difficult. So I would say not to go to Herculean efforts here, just get it to where it works safely and get the replacement gear on order, I doubt you can save it on a more permanent basis.


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