97cf carbon fiber fill tank condemned for a couple cracks in the thread
- Thread starter Airtillery
- Start date
I dont get it. Why do u think these carbon fiber tank blowing up is a joke and doesn't happen? Just cause it didn't happen to you doesnt mean it won't happen to anyone else. Go watch Joe brancato YouTube video on these carbon fiber tanks. They aren't a joke when then go kaboom. 4500 psi isn't something to laugh it.Blow up?Now that’s funny! I don’t care who you are.
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If you read the comments on that video you will find that they intentionally filled that tank to destruction. IIRC it was 10-12K psi. The US Navy says they have NEVER had a tank explode. They submitted that tanks should be retested and given a 30yr lifespan after the 15 year lifespan expires.
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No Navy tanks. No Fireman tanks. No SCBA tanks. NONE have blown in the past 30+ years. That is why I’m laughing at the Blow Up comment. They just don’t fail that way while in use. Think about it. Firemen take these into burning buildings. And no failures. But if you can link to a report of this happening I’ll retract my comments.
They are made to withstand well beyond the pressure they hold,” Russ said. “They won't rupture until the internal pressure approaches about 20,000 psi. They are very safe.”
They are made to withstand well beyond the pressure they hold,” Russ said. “They won't rupture until the internal pressure approaches about 20,000 psi. They are very safe.”
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I took it as poking fun at the language "blow up" rather than saying rupture or explode. If Joe B's tank dun blowed up we better be careful.
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I wish falling back on the warranty were as simple as you portray. The tank vendor, as I was in part expecting, does not believe there could be a crack in the threads and is wanting proof. If it is proven to have a crack, the vendor indicates I will be "taken care of". However, I now have to either ship the tank back to vendor (at my expense) to be inspected, or vendor will ship it off to the manufacturer to assess. Apparently there are only a couple HPA tank manufacturers in the U.S. Or I can pay for yet another $35 VI from a different inspector and see what occurs.
While I fully concur that no one's life if worth $800+, from what I've been reading, even professionals make a misdiagnosis or false positive (or even negatives). As such, for now I'll deem the tank as unusable, pending a second opinion. But even then, if the 2nd VI inspector determines the tank as being safe, in some ways it won't completely instill my full confidence in all this. Of course, to eliminate any bias, I will not inform the 2nd VI inspector of having this previously inspected, until "after" the 2nd inspection, should I go this route. Being very new to air propelled devices and equipment, I do not have years of experience in all this. And because of the potentiality of a serious event, I'm going to err on the side of caution, at least at this juncture until I garner a much greater understanding of this issue and have greater level of confidence in the existing inspection standards and process. The more I read about all this, there seems to be a mixed review of the inspection standards, cooperation between different shops accepting another's annual VI inspection sticker, VI inspectors certifications and competence levels, and at best there appears to be some inconsistencies in it this whole VI process. There are not many places to get ones tank filled, so with these limited options, I'm at the mercy of a particular shops rules.
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That is in part what the tank vendor I bought the tank from has opined, but as I conveyed to "Airmanator", the warranty by the vendor is not so clear cut and dry and unfortunately not with an additional expense out of my pocket, which is a whole different battle.
In regards to your last question: yes this was the same shop and as I previously updated, the "oxygen" issue was resolved and the last time I had it filled at this very shop, there were able to get it to about 4.1k, with a little extra effort. So I was shocked that all of a sudden they sprung this VI requirement on me.
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could be ? they do not want to stress their equipment filling to 4500 so fail inspection for a questionable crack . with the past history i might not want them to fill my tank anyway .
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When it comes to any legal requirements or DOT & ISO regulatory bodies that establish HPA tank standards, I could not speak on this or be able to make a firm statement that annual inspections are "not" required by law. May I ask your source of this seemingly definitive statement? I not able to confirm this either way.
In regards adverse events with HPA tanks, I'm still looking into this. But while there does appear to a few incidents, whenever there is one, it invariable has either a tragic ending or with very significant injury and property damage.
Thanks for pasting in the thread inspection criteria. I did read this. But since such inspections are conducted with an imperfect human that is prone to error based on ones experience, work tolerance and eyesight, it appears per a report by "Luxfer: (http://www.psicylinders.com/inspect...scuba-aluminum-cylinders-made-from-6351-alloy)", that half of all tanks assessed with a thread crack, were "not" cracks at all. This does not instill a whole lot of confidence in those that perform VI!!! And if the the individual had followed the above guideline you posted above, I would not be in possession of my tank. Unfortunately and additionally, the VI inspector that dinged my tank, appeared to skip this step and claimed he was supposed to condemn and destroy the tank. And as I stated in my opening post, I was able to convince the inspector to not take this drastic measure by giving my word as one Veteran to another that I will not fill this tank, but will pursue a replacement with the vendor I bought it from.
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Anything is possible, but even if that were the case, I still have to resolve this in the safest way possible, balanced with what is prudent and counting the cost involved.
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I thoroughly inspected inside my used, out of date Scott SCBA 60 min tank with a Teslong bore light before I filled it for the first time. It was an easy job. I can see how an inspector could misinterpret machining / tapping marks for cracks. If they gave you back your tank, perhaps you could buy a Teslong and take a look for yourself. If you can confirm that they are not stress cracks, consider filling it yourself. Of all the places on a tank, the neck threads seem to me to be the strongest and least likely place for cracks to form. My guess is inspector error.
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I tried doing this and unfortunately it was not easy to capture an image with my cell phone trying to peer through a small microscope with a bright light shining on the alleged cracks, that ended up being washed out by the light, even though we were able to see the lines that appeared to be cracks, or potentially "tap stops" with our eyes. Attached is the image I was able to get, but really doesn't show anything for the aforementioned reasons. The line were were seeing is in the 2nd to the last thread valley from left to right. You will see some shadow like artifacts from the bright light reflecting off the thread metal and right above that is were the supposed crack is at.
As far as your hypothesis on the unlikeliness of a crack something I can not speak on for I have not experience on this nor any expertise on it. May I ask, is your comment based on a presumption or from some form of experience? Thanks...
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IF this is a made in US scba tank then it’s very unlikely to have stress crack by the threads, the threaded section is quite long and evenly distributes the force. From your picture it looks like a scratch/machine mark more than stress/hairline crack.
There still isn’t a known case of certified made in US scba tank or valve fail catastrophically under normal working pressure. I have 3 tanks and zero issues, they all get DOT hydro tested and all pass with flying colors.
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Been following this, just had a thought — how about a partial fill, 500 psi or so then a dunk in water.
I would think a crack would leak...
I would think a crack would leak...
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That looks like a tool mark to me.
It just doesn’t make sense that there would be a crack located in the valley of one thread. Especially on a specialty high pressure tank designed to work under harsh conditions.
I think this is much ado about nothing.
Were it me, I’d fill it up and never give it a second thought.
It just doesn’t make sense that there would be a crack located in the valley of one thread. Especially on a specialty high pressure tank designed to work under harsh conditions.
I think this is much ado about nothing.
Were it me, I’d fill it up and never give it a second thought.
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I would approach the dive shop inspector with my doubts and ask how they determine cracks from machine marks. This test sounds too subjective to be of value. If anywhere close to 50 per cent are misdiagnosed what's the point? I would at least ask the shop the questions I had while I was looking for another dive shop.
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I see nothing that even looks a little like a crack. Did it ever look like an actual crack when you were moving it around?
To get good photos through a scope you need to have a separate light source so that the light isn't directly shining on the area you want to capture. An easy and inexpensive way to do that for your use would be an illuminated knitting needle. You can position the lighted end of the needle just right to give a non glare image. Turn the light on the scope off. I use the knitting needle when inspecting rifle bores as well. If you get one that is fairly long you can insert it from either end to fully light up the entire bore. Sometimes a piece of tracing paper taped on the tip of the needle to act as diffuser helps reduce glare even more.
To get good photos through a scope you need to have a separate light source so that the light isn't directly shining on the area you want to capture. An easy and inexpensive way to do that for your use would be an illuminated knitting needle. You can position the lighted end of the needle just right to give a non glare image. Turn the light on the scope off. I use the knitting needle when inspecting rifle bores as well. If you get one that is fairly long you can insert it from either end to fully light up the entire bore. Sometimes a piece of tracing paper taped on the tip of the needle to act as diffuser helps reduce glare even more.
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Aluminum doesn't like Sharp edges. If it were to crack it would be at the base of the thread or the top not in the middle of the threads valley. Do need a better picture of supposed crack.
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