cloudswinger
Contributor
It seems like you're saying it's fine to pass the problem on to the sucker who buys the tank. Shouldn't the tank be destroyed or something?
Risk with 1972-1988 AL80 Tanks ?
- Thread starter bowtieman427
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It seems like you're saying it's fine to pass the problem on to the sucker who buys the tank. Shouldn't the tank be destroyed or something?
My mistake, I meant to say "it is really that bad to destroy the tank and use it for decoration or something and buy a new one?" That is what happens when I'm running late for class. I'll go edit it so I don't confuse people.
http://www.scubaboard.com/forums/tanks-valves-bands/58443-what-exactly-eddy-test.html
This thread suggests that eddy current testing should only be done to 6351 tanks.
1. Lets face it, cylinder explosions are relatively rare. That being said, over 90% of cylinder explosions occur while filling. I have never denied the 'right' of a fill station operator to refuse to fill the tank (its their life at risk), I am only questioning the merit in certain cases.
2. In the early 80's, Luxfer was presented with the challenge of multiple cylinder ruptures due to sustained load cracking. They discovered their base alloy 6351 was at risk and that a different alloy (6061) was more durable. Following this discovery, DOT determined that a 6351 with NO signs of SLC does not need to be removed from service but ANY sign is enough to condemn the cylinder. This is why it is absolutely necessary for the cylinders to have a thorough inspection. I think most of us know that plenty of facilities perform inspections without proper training and slap stickers on. I think there needs to be more regulation in this part of the industry and serious fines should be imposed through a proactive agency, not a reactive one like OSHA. I am, honestly, skeptical of any 6351 that I or one of my colleagues did not inspect because I know that our inspections on those tanks are given 2 inspections by 2 people using PSI standards...
3. Steel tanks are prone to rupturing just as AL tanks are. One of the biggest problems in the industry is a recording problem as NO facility is required to report a cylinder explosion; this is why it is impossible to get a solid number of cylinder explosions per year. That being said, the last 2 cylinder explosions have been steel.
4. Eddy Current can only be used on 6351 AL's not on any other alloy. The Visual Plus 3 can also be used on 6061 but, to my knowledge, it is not calibrated very well.
5. I have heard of places claiming it is illegal to fill 6351 cylinders or condemning them when receiving them for a visual...is this not defrauding the customer and illegal?
6. I will not refuse to fill a 6351 unless I have probable cause not to. When I do, I tell the customer that I will lend them a rental tank until I am done inspecting the tank. This is the procedure I do with all tanks...When my gut barometer goes sour, I don't fill.
2. In the early 80's, Luxfer was presented with the challenge of multiple cylinder ruptures due to sustained load cracking. They discovered their base alloy 6351 was at risk and that a different alloy (6061) was more durable. Following this discovery, DOT determined that a 6351 with NO signs of SLC does not need to be removed from service but ANY sign is enough to condemn the cylinder. This is why it is absolutely necessary for the cylinders to have a thorough inspection. I think most of us know that plenty of facilities perform inspections without proper training and slap stickers on. I think there needs to be more regulation in this part of the industry and serious fines should be imposed through a proactive agency, not a reactive one like OSHA. I am, honestly, skeptical of any 6351 that I or one of my colleagues did not inspect because I know that our inspections on those tanks are given 2 inspections by 2 people using PSI standards...
3. Steel tanks are prone to rupturing just as AL tanks are. One of the biggest problems in the industry is a recording problem as NO facility is required to report a cylinder explosion; this is why it is impossible to get a solid number of cylinder explosions per year. That being said, the last 2 cylinder explosions have been steel.
4. Eddy Current can only be used on 6351 AL's not on any other alloy. The Visual Plus 3 can also be used on 6061 but, to my knowledge, it is not calibrated very well.
5. I have heard of places claiming it is illegal to fill 6351 cylinders or condemning them when receiving them for a visual...is this not defrauding the customer and illegal?
6. I will not refuse to fill a 6351 unless I have probable cause not to. When I do, I tell the customer that I will lend them a rental tank until I am done inspecting the tank. This is the procedure I do with all tanks...When my gut barometer goes sour, I don't fill.
Which two cylinder explosions are you talking about? I know of a steel bank that split, but that was not a scuba tank, per se, and wasn't it established that the tank was not properly inspected?
And yes, I believe it is wrong to tell a customer that it is illegal for a tank to be filled, or condemning it. I do not condone that, I only tell customers that I will not fill their tank and they can go elsewhere if they want it filled.
The 'cylinder explosions' I am referring to are not unique to scuba cylinders for breathing gas but cylinders made from the same alloy and grade. The first explosion was from the steel bank bottle and the second one was a scuba cylinder...I cannot find the investigative report but if you call PSI, like I did, they will give you the details...I believe there may have been another one regarding a steel cylinder in Cypress, I am pretty sure they can give you more info on that too.
It would be nice to have a quick reference database and I think PSI/CGA/DOT should mandate reporting and put it on the web...Call them for the details, I doubt they will have a problem sharing them.
It would be nice to have a quick reference database and I think PSI/CGA/DOT should mandate reporting and put it on the web...Call them for the details, I doubt they will have a problem sharing them.
klauricella
Contributor
How many of the older alum have actually ruptured. I was under the impression that only a few and those had questionable inspections. If you have a 20 year old tank with only a few fills on it is it worse then all the older rental tanks that probably had 1000s of fills with no problems. I under stand being caution as long as it is backed up by facts and not rumors floating around the internet. If these tanks were that dangerous I would think that the manufacturer and DOT would just say do not fill. Shop owners do have the right not to fill I was in a shop the owner refused to fill one of my tanks that had a current VIP and hydro, when I questioned him he could not give me a reason only that all older tanks are bad then tried to sell me a new one.
The FDA leaves "risky" drugs on the market because in their eyes the benefits to a population of patients outweight the risks to the few who will have an adverse event. When the adverse event is sudden death the benefits have to be pretty high or the replacement options very costly or non-existant.
For the 6351 cylinders in question, I see few benefits ot keeping them in service. They require additional eddy current inspections, and those machines and training for them aren't cheap. E.g. my hydro place charges an extra $12.50 for VEs, nevermind annual eddies (which are probably a good idea). The costs of replacement cylinders are not very high, esp. used 6061s which I can find for ~$80.
Buying a used 6351 cylinder for more than a few dollars is not cost effective IMHO because there's a very real chance it will fail eddy current or visual next year or the year after. So your money is wasted vs. just getting a 6061 cylinder now (new or used).
6351 cylinders remain DOT approved because there have only been a few explosions (~dozen or 2) and they are in very wide circulation, esp. as CO2 tanks. The costs of replacing all those cylinders is very high. The benefits could only accrue to the few people who wouldn't be killed or maimed by an improperly inspected cylinder exploding. Population wide those explosions are rare, so the cylinders remain in service despite their increased risk. Just like some types of "risky" drugs.
Just like some patients may read the complete drug label and decide the frequency or magnitude of an adverse event is unacceptable to them, some dive shops may chose to not fill 6351 cylinders. The frequency of a 6351 aluminum cylinder adverse event may be low, but the magnitude is quite severe.
For the 6351 cylinders in question, I see few benefits ot keeping them in service. They require additional eddy current inspections, and those machines and training for them aren't cheap. E.g. my hydro place charges an extra $12.50 for VEs, nevermind annual eddies (which are probably a good idea). The costs of replacement cylinders are not very high, esp. used 6061s which I can find for ~$80.
Buying a used 6351 cylinder for more than a few dollars is not cost effective IMHO because there's a very real chance it will fail eddy current or visual next year or the year after. So your money is wasted vs. just getting a 6061 cylinder now (new or used).
6351 cylinders remain DOT approved because there have only been a few explosions (~dozen or 2) and they are in very wide circulation, esp. as CO2 tanks. The costs of replacing all those cylinders is very high. The benefits could only accrue to the few people who wouldn't be killed or maimed by an improperly inspected cylinder exploding. Population wide those explosions are rare, so the cylinders remain in service despite their increased risk. Just like some types of "risky" drugs.
Just like some patients may read the complete drug label and decide the frequency or magnitude of an adverse event is unacceptable to them, some dive shops may chose to not fill 6351 cylinders. The frequency of a 6351 aluminum cylinder adverse event may be low, but the magnitude is quite severe.
klauricella
Contributor
The thing is the DOT can ban them if they are truly dangerous I would not think that there is a 20 year warranty on tanks. No cost would be incurred except for the guys buying new tanks.
DaleC
Contributor
I must be a crazy man because I can never figure out how people become so fixated with the minute perceived risk of 6351 tanks while apparently ignoring the very real risks all around them. Have any of those opposed to these tanks quit driving? The risk is far greater of dying in a car wreck. Walking outside in a storm? The risk is far greater of dying via lightning strike.
Tech diving? Wreck diving? Cave diving?
If such minute risks bother people how do they ever suit up and SCUBA dive at all? The risk is far greater that you will die from that act alone, than from a 6351 tank.
Tech diving? Wreck diving? Cave diving?
If such minute risks bother people how do they ever suit up and SCUBA dive at all? The risk is far greater that you will die from that act alone, than from a 6351 tank.
Since 1972, 22 aluminum SCUBA tanks have been reported to have exploded. Over the same time period, 56 Steel SCUBA tanks were reported to have exploded. In general, the failures of both types were due to abuse, improper maintanance and improper inspections.
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