Letter 7358

Help with plating tank height requirements 

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Greetings - I need help! My company is currently considering an expansion. We are getting conflicting reports of tank height requirements for metal finishing facilities. Some tanks will be used in a hand line for racks weighing approx. 10-20 pounds. Other tanks will be used for barrel plating primarily. Are there any tank height requirements? Are they published anywhere? Many thanks for this great forum and all the helpful finishers out there!

Victor Waldman
- Naugatuck, CT. USA

In a word: 42"

The longer answer is that there is an OSHA rule about walkways above pickling and galvanizing lines requiring standard 42" high railings, which has, by continuing usage, been extended to involve all plating lines. And rightfully so, I might add, because there have been many fatalities and injuries from workers falling into plating tanks.

In the case of automated lines, barrel plating lines, etc., the best solution may be to put the rims at 42" and dispense with any railing. Most people, including OSHA inspectors, can easily appreciate that adding a railing to such an installation adds dangerous pinch points; and that if the danger of falling into the tank can be alleviated by setting the rims at 42" without adding any pinch points, that is the best solution.

Still, the ideal situation from an OSHA and liability standpoint, and it may work well for your manual line, would be to put the tank rims at a more workable height of say 33", and then put a standard pipe railing around them 42" off the floor. I've seen this done is some aircraft rework facilities and it can be workable.

The advantage to this is that workers will be protected to 42", but only have to get the bottom of the 10-20 pound rack 33" above the floor. I have seen installations with 42" tank rims where shorter workers end up climbing upon a stool, or some excuse for a stool, and find themselves back into the possibility of falling into the tank.

 
Ted Mooney, P.E.
finishing.com Inc. - Brick, NJ

Peter Drucker in one of his books asks/answers a question "How big should your company be" with the answer, that "Size should suit the function"! It's not very different with Plating Tanks. Depends on the Electrolyte. I like my Zinc Tanks deep as I let sleeping sludges lie. However my Nickel Tanks not deeper than 8 inches below the rack so as to get any residual waste into the filter and not lie in the tank. Also keeps the heating costs optimum and uniform till bottom.

Post more details about the process and component sizes.

Khozema Vahanwala Saify Ind   Bangalore, Karnataka, India

Ted,

I read with interest your response to an inquiry on plating tank heights in a recent Metal Finishing publication. I wonder if you wouldn't mind elaborating a little further on situations where this regulation has been applied to companies with tank heights of less than 42 inches.

The company I work for has automated electroplating/conversion coating lines. With the exception of one individual per line who monitors the chemistry and makes additions when required, there is very little work required around the tanks. The height of our tank rims is approximately 28 inches above the catwalk. The opposite side of the catwalk is protected by a 42-inch railing.

Have there been precedent setting rulings you are aware of, by the Standards Board, that compel the installation of higher protective railings? The company I work for has never had a related loss in 35 years, so I will need something compelling to present to management if we are to contemplate the modifications. Also, I was not able to visualize the setting where you described a 33-inch tank height with a 42-inch standard pipe railing around it. If the railing is immediately around the tank, it seems that the operator would still have to get the bottom of the rack 42 inches in the air to get it over the rail and into the tank.

I would appreciate any additional information you are able to provide.

Mark Smith
- Santa Fe Springs, CA, USA

I will be happy to clarify.

First, some people were confused by my statement "put the tank rims at a more workable height of say 33", and then put a standard pipe railing around them 42" off the floor", asking me how this saves the operator from having to lift the bottom of the work 42" off the floor. Well, these railings are along the rim area of the tanks, but if the tanks abut one another, there is no pipe railing between the tanks, so the wet drippy work need be lifted only above the rims:

For the rule itself, as printed, please see www.osha-slc.gov/OshStd_data/1910_0023.html#1910.23(c)(3)

As for my interpretation of the OSHA rule, please see www.osha-slc.gov/OshDoc/Interp_data/I19791129.html and I think you will infer the same things that I do. But if anyone is hurt by falling into a tank, an after-the-fact assertion that OSHA might have considered the violation "de minimis", had a variance actually been sought, sounds like pretty weak ground to stand on anyway. Having been an expert witness on the defense side of the table in several cases, I would not have been very comfortable had the tank rims neither been at 42" nor was there a railing.

Obviously, it's not possible to fall into a very small tank, but people used to fall into large plating tanks frequently in the old days when rims were 21" to 24" off the walkway and they got caught at the back of the knee. I am 6' 4" tall and to me 26 to 27 inches is still a back-of-the-knee problem (I just checked it with some low tables). 28" is getting into the "iffy" range. A height of 30" is obviously better, but who can argue that 33" to 36" or the European standard 1-meter is still better, but that the ideal is the same height you would want on any protective railing?

If you walked onto the balcony of a 10th floor hotel room and the railing was 28" or even 30", how comfortable would you feel? Plating tanks are often HOT enough to burn a person so severely in a few seconds that death is inevitable. You should feel no more comfortable standing next to a large 165 deg. F tank than you feel on a 10th floor balcony.

It's all just my opinion, and yours is welcomed.

Ted Mooney, P.E.
finishing.com Inc. - Brick, NJ

Hi Victor and Mark,

It sure seems that poor old Ted has gone to a lot of work for you people. Lucky you.

Regarding Ted's 2nd last para about tank heights, I cannot help thinking of the adage, RULES ARE TO BE (blindly?) OBEYED BY IDIOTS BUT ARE A GUIDE TO WISE MEN !

A good ergonomic access height is 36", ie. a hair to two more than a metre.

In the case of fumehoods having large hotplates, they should not be over 30" high because the operator has to be able to easily access any beakers & petri dishes on the 6" or so high(er) hotplates.

Regarding hotel railings ... well, over here railings now have to be 42" but low level large plating tanks would frighten me. Never seen any, coming to think of it.

May I then suggest for small tanks you elevate to the good ergonomic height of 36" as this would make it much easier for the worker = increased productivity, too. For Asiatics, ah, you'd maybe need to be a few inches less.

Cheers !

Freeman Newton
plastics fabricating (design) background - White Rock, B.C. Canada

I'll bet most Americans saw the recent return of the spy plane crew, Freeman. Some crew members were at least as big as defensive linemen, whereas one of the female crew members was exceptionally small, barely coming up to the stomach of the guy she was standing next to. I hope that pair isn't considering retiring to the plating industry. How can we design an ergonomically correct plating line considering things like that?

Ted Mooney finishing.com Brick, New Jersey

(In reply to Ted Mooney's last rejoinder)

Sir!

I doubt very very much that the crew of the spy plane would be as tall as you give yourself to be, ie. 6'-4" as they'd have seating problems.

But isn't 6'-4" THE exact height of another Irishman, one Serjeant Harper from the book of the superlative SHARPE series by that now-living-in-the USA author, Bernard Cornwell? ... a few, but only a few inches more than me but doubtless much. much heavier! Every time I read about Sgt. Harper I think of Ted Mooney! Maybe Cornwall got that idea from you, eh?

Freeman Newton
- White Rock, B.C. Canada ... where the water is purer than any politician

Ed. note: also see letter 10023.

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