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Post by diverdon on Mar 25, 2014 7:54:03 GMT -8
So I was anxiously waiting for my babies to come back from hydro, and due to the fact that the nearest place to do these is 90 miles away, I wasn't going to get them til Friday. On a whim I called and talked to the technician.  He informed me that 5 failed and 4 survived  Most of these were extremely old and I didn't expect all of them to pass but I'm sure not running out to get lottery tickets. I have seen them cut up and made into bells, but I'm not interested in that. What have you all done with failed tanks? Does anyone use them to display their vintage regulator collection? |
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Post by nikeajax on Mar 25, 2014 8:21:37 GMT -8
Awww-man, bummer!
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Post by sitkadiver on Mar 25, 2014 8:24:27 GMT -8
I'm surprised. I think I stated in the other thread that you shouldn't have any problems.... Was it the threads? I didn't see any pitting in the photos.
Sorry to hear that.
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Post by diverdon on Mar 25, 2014 8:29:07 GMT -8
I'll know more when I can see the tech FTF. I couldn't get the valves off three of the tanks so there could have been rust. One had no air in it but it was donated to the cause so I wasn't holding my breath there. What is thebest meathod for cutting the tops off to display regs? Oxy-acet torch?
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Post by sharkman4928 on Mar 25, 2014 21:29:33 GMT -8
Band saw.
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Post by diverdon on Mar 26, 2014 2:10:47 GMT -8
Yep. Band saw. I went to the local John Deere dealer and bribed the owner with ale  |
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Post by nikeajax on Mar 26, 2014 9:10:40 GMT -8
Spoken like a true diver...
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Post by diverdon on Mar 27, 2014 16:06:07 GMT -8
So here are a couple pics of the tanks that I sent out. The ones in the back failed and I'll be cutting them up for display. And the four in the front passed. The one with the yellow boot has raised DACOR on it. Iforgot to take a pic earlier but I will:  Failed:  But soon they'll look like this:  So the Healthways can sit here and look all pretty till the parts come in:   |
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Post by luis on Mar 28, 2014 3:19:05 GMT -8
Did they fail hydro or VIP (due to rust)?
Did they condemned them by XXXX the DOT numbers (or stamping condemned on them) or did they just write with a magic marker.
If they fail due to rust, they can probably be tumbled and be brought back into service. The three with the 3/4 inch neck are easy to tumble of use a wire whip. The two with the 1/2" neck are a bit of a pain.
If all 5 tanks fail hydro, the only explanation is that the hydro tester did not follow the proper pre-test procedure and they screwed up. Those are all 3AA steel cylinders and unless they were all in a fire, it is statistically improbable to have 5 (out of 8) 3AA cylinder fail hydro. I don't think you will see 5 cylinder (3AA type) all fail in one day in all the hydro stations in the US, unless someone screws up.
If they have not been condemned (by crossing the numbers with XXXXX), you have several options. Do not cut them up, that is a waist.
I had 3 cylinders condemned by a local hydro shop. I would have accepted one, but not three. I asked for the hydro data and sure enough they screwed up. They don't only did not follow the proper pre-test procedure, they were being conservative on their pas/ fail criteria. The criteria is set by the CFR (Code of Federal Regulations) and it is not up to the operator to be conservative. They destroyed three perfectly good tanks and had to replace them.
You can demand to see the hydro data. The hydro data belongs to the DOT and they are required to provide it if requested (but many hydro stations do not know that). It is perfectly legitimate for the hydro test station to re-test and prequalify a pressure cylinder if they fail them (due to their error), but not if they condemned it (by XXXX the numbers). If they condemned them due to error, they owe you new tanks, but that is a bit harder to prove, unless the data shows it. I can help you on how to read the data if need it (see note).
Or you can just take them to another hydro station and have them re-tested. Just make sure they do the pre-test round-out procedure required by the manufacturers of galvanized cylinders.
Bring a printed copy of the procedure with you. You can down load the pre-test procedure from the down load section of VDH.
Please, do not destroy good old cylinders just because someone made a mistake. Most hydro station operators do not deal with galvanized tanks that often and they are not aware of the pre-test procedure. The procedure should be done to all steel cylinders, but it is imperative with galvanized cylinders. Many cylinders will pass without the pre-test procedure, but the chances of failure are much higher.
With the pre-test procedure most steel cylinders pass with very low permanent expansion numbers.
Note: I started doing hydro tests during my first job in a dive shop over 40 year ago. After that I also got some engineering degrees and in a couple of my jobs I have worked on the design and qualification of pressure cylinders.
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Post by diverdon on Mar 28, 2014 4:51:06 GMT -8
Luis,
Thanks for the info. I asked the gentleman who performed the hydro and he said he "couldn't test them because of the rust". I asked about tumbling them and he said some pits were "pretty deep". He didn't xxx out the numbers though.
I'll have to try and stop the fellows at the shop where I dropped them off. All of this is a real PITA as the closest hydro shop is 90 miles away and open during limited (read my) work hours.
Thanks again for the info. I hope you don't think I'm ranting and I really hope I'm not too late.
Don
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Post by diverdon on Mar 28, 2014 4:55:57 GMT -8
Luis,
About my other tanks. Is it OK to sand blast them with silica sand and repaint them? I understand you don't want to remove metal, but in your opinion what is the best way to make a tank more presentable?
Thanks in advance,
Don
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Post by luis on Mar 28, 2014 14:42:33 GMT -8
You don't really want to sand blast the exterior of a galvanized (or even a painted tank). Even if you didn't do any damage, many dive shops will be suspicious and will not fill them.
The galvanized finish is the absolute best finish you can get and there is no need to do anything to it. It is the best protection and therefore, in my opinion that makes the best looking finish you can get.
I can't tell for sure if the painted tanks have a galvanized finish under the paint. If they are galvanized I would not worry about them. If they are not, I might consider chemically striping the paint and using CRZ (cold galvanizing paint)... or I may just go diving and don't worry too much about. Just remove any rust and touch up the spot.
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Post by nikeajax on Mar 31, 2014 13:56:36 GMT -8
Don, have you looked around for a place that does fire extinguishers to do your hydro's? When I get time I'm going to take those tanks I got from you to a place called Acme Fire Extinguisher: yeah, I know EVERYONE thinks of this when they hear Acme:  Jaybird |
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Post by diverdon on Mar 31, 2014 16:39:27 GMT -8
Sweet. I wanna open an Acme dive center. About those tanks, I dropped them off and haven't been able to pick them up yet. I'll keep looking around for another place but I have 10 or 11 tanks right now. I don't really need any more. Except maybe some double 72s... Funny, one of the ones I did have hydro'd has a leaky valve. The reserve side has a slow leak and the pitch changes a little when I engage the reserve. Ant idea where I can get a schematic of this valve? Or a kit? Never rebuilt a valve before.  |
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Post by nikeajax on Mar 31, 2014 16:54:10 GMT -8
Don wha'cha wanna get is a copy of Basic Scuba, second edition: it's the revised edition... for some reason this book will fetch money that will give you a coronary:$2,242.59, but that doesn't mean people are paying that much! Every once in a while you can find it on Alibris for a REAL price...
Jaybird
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He informed me that 5 failed and 4 survived 
Most of these were extremely old and I didn't expect all of them to pass but I'm sure not running out to get lottery tickets. 
