Old steels denied fills due to store "policy"

[txgoose]

You got me... I exchanged sexual favors in a dark alley for the tanks in question.

I realize that we are not supposed to bash the various diving agencies, but somebody should have tought you to CESA before it ever got to this point.

 

[fullytek]

Some one asserted that the vip had been done by the shop in question . I would like to see if that is true.

I would not fill that tank in my shop if that means all you keyboard warriors are going to boycott my shop and my boat then give er.
You will miss out on some fantastic shipwreck diving . And before you say well if I go out of business some one will take my place well your wrong. Good luck finding someone willing to loose 10 grand a year running a federally compliant vessel in a niche market.

Free enterprise allows the dive shop to refuse to fill for any reason.

You were offered rental tanks of which you refused. You were not wronged or ripped off. Your intention for starting the thread was only to slander force e scuba.

 

[Boiler_81]

I'm also an ME and do agree to the theoretical points. However, if you look at data from failures, there is nothing which says we should be putting tanks out of service which have met the hydro and visual inspection criteria. I would even argue that the visual is of no use as long as the cylinder was never run down to atmospheric pressure.

Sometimes we engineers overthink the theoretical points and ignore the empirical data.

I dive a US divers 1953 concave bottomed cylinder with one of my early double hose regulators. It is clean inside and passes hydro every five years. I have no concern filling it or diving it.

Okay... I am (was) a metallurgist, I worked within the Aerospace sector, with my speciality being Non Destructive Testing.

Allow me to pick up on a couple of points.



Visual Inspection is subjective - incredibly so. You might be surprised to learn that a professional visual inspection course for Level II that allows some to inspect and decide if a component is serviceable or not has a minimum course length of 40hrs and certainly doesn't cost a mere $200 A professional qualification has to be re-certified every 3 year - you go through the whole examination process again

The trouble with vis is that some inspectors can be absolutely spot on and well trained, at teh other extreme some might have been asleep in class or couldn't care that day. I've had the unfortunate responsibility of attending 2 air crashes where the prime cause was a defect clearly missed during inspection.

So vis is really only worth while to see if there are any major problems.



Sort of. A hydro measures the materials elastic properties which can change over time. A material can become both more or less elastic. So yes in that you are correct.

But that's all it does (apart from testing the ability to hold pressure) It cannot measure any stresses nor detect any fatigue cracks or stress corrosion for instance. A cylinder can have these underlying defects, pass hydro and vis and still go bang on a pressure fill.



Our knowledge of metallurgy is great, but we don't' know it all. I gave up being surprised when a component would fail unexpectedly havign been stressed modeled and designed to the nth degree. Cylinders are over engineered - massively so, because the raw material is of commercial grade and has the potential to include all sorts of defects. While batch testing of the raw material can pick up if its a bad composition or heat treatment and later poor manufacturing quality it can't guarantee the material is perfect. Hence they over engineer because the raw material is cheaper than 100% testing.

Cycle testing of cylinders is there to ensure they can stand pressure cycle fatigue. You can't fully test for environmental and handling conditions as there are too many variables.

Tumbling etc will remove material wall thickness which may have no effect on hydro but will cause stress concentrations. Generally not an issue but given teh right circumstances it will cause an initiation point for a failure. That defect might be fast or slow growing.


Now it's perfectly acceptable and rational to look at failure rates over time vs number of cylinders and declare that the risk of failure is low. We do it all the time. But using that as a bases to have unlimited life on a cylinder is
foolhardy.

The ONLY people who can give a predicted life expectancy in teh real world are the manufacturers, and they would err heavily on the side of caution.

We are all scuba divers who are cautious with our equipment. People debate until they go blue about "additional failure points, O rigs and plastic buckles" and yet will happily insist that cylinders are good to be overfilled and can be used forever because there hasn't been a problem...

I'll admit I'm an engineer and cautious - from experience. my personal opinion that a 50yr old cylinder is well overdue to be turned into a bell or astray

If you had more rigid and meaningful inspections that might not be the case, but the cost of such would not be cost effective.

Is 30 years too much I don't know (without data) but if a shop wishes to err on the side of caution then we should respect that.

$300 for a new cylinder and 5 years hydro free? Cheap I say

 

[Boiler_81]

Some one asserted that the vip had been done by the shop in question . I would like to see if that is true.

I would not fill that tank in my shop if that means all you keyboard warriors are going to boycott my shop and my boat then give er.
You will miss out on some fantastic shipwreck diving . And before you say well if I go out of business some one will take my place well your wrong. Good luck finding someone willing to loose 10 grand a year running a federally compliant vessel in a niche market.

Free enterprise allows the dive shop to refuse to fill for any reason.

You were offered rental tanks of which you refused. You were not wronged or ripped off. Your intention for starting the thread was only to slander force e scuba.

I think you should look up the definition of the word slander. Nothing in the original post is untrue. E Force does refuse to fill older cylinders.

 

[Billy Northrup]

And that is maybe valid. But that isn't what's going on here. The cylinders had VIP stickers from the very shop that refused to fill them.

I was trying to distract

 

[txgoose]

*gives @Boiler_81 the side eye*

Does your VIP class come with Kolachies???

 

[swimlikethefish]

I would not fill that tank in my shop... before you say well if I go out of business some one will take my place well your wrong. Good luck finding someone willing to loose 10 grand a year running a federally compliant vessel in a niche market.

Free enterprise allows the dive shop to refuse to fill for any reason.

Sounds to me like losing 10k a year you won't be around too much longer. The other thing about free enterprise... It allows me the consumer the opportunity to decide where I spend my money. Looks like next time I'm in the lakes region I'll stay on the U.S. side.

 

[Boiler_81]

*gives @Boiler_81 the side eye*

Does your VIP class come with Kolachies???

You are confusing the intro class with with advanced class which is priced at $5K. Inspectors who graduate from the advanced class are 2.5 times better than inspectors from the intro class.

At some point I will develop some specialty classes for which I will issue cards with pretty pictures on them.

 

[gcarter]

Let's see the vip?

You aren't doing yourself any favours with this crusade on behalf of a shop not your own that utterly failed customer service 101. You are managing to fail yourself, and it isn't even your issue.

I know one shop I will never visit, one charter I will never book.

Can you guess who?

Fully Tek

 

[tmassey]

I'm also an ME and do agree to the theoretical points. However, if you look at data from failures, there is nothing which says we should be putting tanks out of service which have met the hydro and visual inspection criteria. I would even argue that the visual is of no use as long as the cylinder was never run down to atmospheric pressure.

Sometimes we engineers overthink the theoretical points and ignore the empirical data.

I dive a US divers 1953 concave bottomed cylinder with one of my early double hose regulators. It is clean inside and passes hydro every five years. I have no concern filling it or diving it.

Thank you for writing that. It's a much more concise version of what I would have written. When the odd of something happen are less than 50 in well over 1 million, it no longer is something that we should make more safe, given the amount of risk we routinely take on in our lives moment to moment. Even if the cost of that extra "safety" is nearly free -- and *especially* when that "safety" comes at a noticeable cost.