Old steels denied fills due to store "policy"

[Vicko]

I would not like to be in a room with 50 year old tanks while they are being filled. Hydro or visual are not good enough to test for material stress and/or structural damage and the roof of my compressor room is worth a bit more to me than customer satisfaction for the niche vintage tank lovers.

On the other hand there are Helium tanks in circulation that are from ww2...

 

[Wookie]

Like @broncobowsher I'll play devils advocate and be unpopular at the same time

The issue with cylinders, is that there is no real record of their history. Vis inspection is almost comical and incredible subjective requiring minimal training (I use the word training in the loosest possible sense). Hyro is only a go/no go based on the elastic properties of the material. It's good enough most of the time - but as you get to the extremes of age it becomes less so.

With a Steel tank (especially) you have no proof of history - even if you're the original owner. The shop has no idea if you've tumbled the tank on numerous occasions or used abrasives on the external faces to remove corrosion. They have no way to assess if the wall thickness of the tank is within limits.

You could easily do this with a simple ultrasonic inspection - but shops don't have the expertise. The time and effort to "re-cert" a tank would be more than the tank

At some point you need to accept that equipment has a finite life. 48 and 49 years of age is getting pretty much past it, So I can understand a shops reticence. Given the cost of diving new Tanks are small beer. Replace them I say.

I disagree, but I'm not an expert.

The reason a hydrostatic test is performed on a steel tank is not really to make sure it will hold the pressure, although that is certainly the first thing you look at, but to ensure that the tank maintains it's elasticity. Screwing with the wall thickness by mechanical means (tumbling or whipping) will certainly destroy the ability of the cylinder to spring back into shape.

So performing a hydro is exactly what determines whether the cylinder has retained it's wall thickness and elasticity. If wall thickness were a certification requirement for old cylinders, don't you think a UT gauge would be a required tool to certify tanks? UT gauges are cheap, even I have one. The company I work for has 3 or 4, some of them work underwater. This is not an expensive technology, certainly cheaper than an eddy current gauge.

 

[Wookie]

I would not like to be in a room with 50 year old tanks while they are being filled. Hydro or visual are not good enough to test for material stress and/or structural damage and the roof of my compressor room is worth a bit more to me than customer satisfaction for the niche vintage tank lovers.

On the other hand there are Helium tanks in circulation that are from ww2...

I guess because I used to fill tanks for a living, I have no problem with filling old cylinders.

I guess that's the difference between science and feels. You give both the same weight, and then you lose customers.

 

[rhwestfall]

UT gauges are cheap

quite: https://www.amazon.com/UM6500-Handh...ocphy=9005488&hvtargid=pla-568862815333&psc=1

 

[Sam Miller III]

Ana
You had two choices
Purchase new SCUBA cylinders from the shop to insure they will be filled
Or
Trot your old vintage antique SCUBA cylinders to another friendlier shop who will fill them

You made the correct choice
The old shop is happy that they didn't have to fill your units
The new shop is delighted that they have a new customer

I now question what would occur if a gas station refused to fill the gas tank of a 10? or 20? year old automobile ?

SDM

 

[seeker242]

One of our LDS's has a similar rule, Once a piece of equipment is 15 years old they refuse to service/fill it.
They will be their own undoing.

Unlikely that it will be undoing for Force-E. They have had this policy for about 20 years now and they are still doing fine.

 

[Diving Dubai]

I disagree, but I'm not an expert.

The reason a hydrostatic test is performed on a steel tank is not really to make sure it will hold the pressure, although that is certainly the first thing you look at, but to ensure that the tank maintains it's elasticity. Screwing with the wall thickness by mechanical means (tumbling or whipping) will certainly destroy the ability of the cylinder to spring back into shape.

Yes and no. Certainly if you had a uniform loss of wall thickness you'd be right but the hydro in its current form is a rather crude method.

Now if you used laser shearography and did the same (although applying a partial vacuum would be better) then you'd have a much better test. Materials used to be my speciality, but since I haven't actively practice in over 10 years, I would need to revise the details. Bear in mind I used to write NDT procedures for the UK and US military and commercial aerospace and thi ws my area of expertise.

And I take you point about UT thickness gauges being cheap. But again here they're better for averaging larger areas. and while they're easy to use, sometime interpreting the meaning of the results requires more than a "users" knowledge

There are lots of different ways I could propose that would adequately certify a tank - but they're not cost effective. 18 months ago I assisted in developing a method of examining carbon wrapped tanks - trouble was the cost of the inspection was greater than a new cylinder

Anyway by original opinion is still the same at some point you need to accept items no longer have a usable life.

If it's about losing customers you can't please all of the people all of the time

 

[Wookie]

Unlikely that it will be undoing for Force-E. They have had this policy for about 20 years now and they are still doing fine.

If it's about losing customers you can't please all of the people all of the time

And this is the bottom line. Their fill station, their rules. And having been an operator, with rules that some felt were too onerous, I completely get it.

 

[Diving Dubai]

quite: https://www.amazon.com/UM6500-Handh...ocphy=9005488&hvtargid=pla-568862815333&psc=1

What reference piece will you use or would you?
Stand off?
Different diameter of cylinders?
How do you know if your signal has transitions from compression to shear wave - what could be the cause?
Paint thickness? corrosion? What would be the effects?

Asking for a friend...

 

[scubadada]

Hi @Ana

Where does your husband usually get your tanks filled? Was this the 1st time you went into this Force E for fills or was it just the 1st time on a weekend?