Old steels denied fills due to store "policy"

[BRT]

If its all the same to you, I'll r ate my years on metallurgical and NDT experience above that of someone who's done a 1 or 2 day "inspection course" YMMV

For the record, I recently carried out Eddy current (VE) and Ultrasonic inspections on a batch of personal cylinders belonging to me and a couple of friends (roughly 60) mainly steels but a few Al 80 and S40's for piece on mind

I found 1 small neck crack (not detectable by vis) and 2 material voids

All had just passed hydro and vis

Neck crack in an AL?

 

[AfterDark]

ooooooh how dare you? hmmmm what cowboy attitude ! ...and you are saying that openly in a forum where everyone can read this.
Now some new diver is going to somehow misinterpret your post and go diving with his grandmother's fire extinguisher.... unbelievable!!!

Free speech baby! Take it up with DOT it's their policy not mine. That hypothetical new diver of yours, someone that stupid shouldn't have a C-card.
Like the owner of the your former LDS too stupid to own a dive shop, for long away.

 

[OkByMe]

ooooooh how dare you? hmmmm what cowboy attitude ! ...and you are saying that openly in a forum where everyone can read this.
Now some new diver is going to somehow misinterpret your post and go diving with his grandmother's fire extinguisher.... unbelievable!!!

What was said about tanks being up to the job by conforming to the DOT inspection and testing requirements is absolutely correct. The presumption that the testing is done by a "fire extinguisher" shop is somehow deficient lends to my conclusion that you don't understand the industry or the technology, and that if you were more informed would bring surprise to you.

IF you check with your LDS, in which you apparently have absolute confidence in, you will find that they do not have the facility to hydro-statically test any cylinder (pressure vessel) and they have to use a facility that does. Which means that their handling markup added to the vis and hyro cost they pay, drives your cost to more than $50. It costs hundreds of thousands of $ to open a facility with the equipment, personnel and warehousing space for thousands of cylinders cycled through from all the business using compressed gas and pressurized liquids.

A local business community has tens of thousands of cylinders in service from bank CO2 and other inert gas fire extinguishing systems. There are food processing, bottling/canning plants that typically use CO2 and Nitrogen. Hospitals and emergency services with their supporting gases. And then there are manufacturing plants which use the daily bulk of gas used for welding, heat treating and corrosion control. And, if you live along the coast and/or have a sizable airport, you can include that into to the overall service usage data, And if I had to guess, which I don't, I would find that the service of these pressure vessels are carried out by "fire extinguisher" shops.

I would challenge anyone to go to the service facility and ask them of the age of the tested items and you would find answers like all the way back to World War 2 and before. Another brow raiser would be the statement of the amazingly small percentage of condemnations of these older cylinders. Pressure vessels, just like any technology are ungraded and replaced based on their suitability for the job and/or failure analysis, then there is cost of retro-fit. Everyone wants the smaller, lighter, less maintenance, higher volume PV's and the SCUBA industry is no exception. Do not exclude the marketing pressure for sales over suitability for the evolution.

Any pressure vessel made of any approved material, absent the related corrosion and damage, will last for centuries if it just sits there. However, once a pressure cycle begins which causes expansion/contraction, a process begins which will over time degrade the strength and elasticity of the material. That is why, in some applications, like aircraft - Some PV's will have a cycle limit or age limit {the age limit is imposed by the application for which it is used and having a high cycle rate projection and the cycles not logged}. Therein lies the need for the means to reliably test and manage of worlds inventory for the sake of safety and reliability.

And just to address the to dive with the extinguisher quip. Most that you could pickup and strap on of similar size to SCUBA are at most 2250, but usually 1800psi and low volume, and they have a different valves and neck thread - See CGA dedicated pressurize vessel and valve specifications - to prevent anyone from cross purposing or a wrong gas fill.

 

[AfterDark]

What was said about tanks being up to the job by conforming to the DOT inspection and testing requirements is absolutely correct. The presumption that the testing is done by a "fire extinguisher" shop is somehow deficient lends to my conclusion that you don't understand the industry or the technology, and that if you were more informed would bring surprise to you.

IF you check with your LDS, in which you apparently have absolute confidence in, you will find that they do not have the facility to hydro-statically test any cylinder (pressure vessel) and they have to use a facility that does. Which means that their handling markup added to the vis and hyro cost they pay, drives your cost to more than $50. It costs hundreds of thousands of $ to open a facility with the equipment, personnel and warehousing space for thousands of cylinders cycled through from all the business using compressed gas and pressurized liquids.

A local business community has tens of thousands of cylinders in service from bank CO2 and other inert gas fire extinguishing systems. There are food processing, bottling/canning plants that typically use CO2 and Nitrogen. Hospitals and emergency services with their supporting gases. And then there are manufacturing plants which use the daily bulk of gas used for welding, heat treating and corrosion control. And, if you live along the coast and/or have a sizable airport, you can include that into to the overall service usage data, And if I had to guess, which I don't, I would find that the service of these pressure vessels are carried out by "fire extinguisher" shops.

I would challenge anyone to go to the service facility and ask them of the age of the tested items and you would find answers like all the way back to World War 2 and before. Another brow raiser would be the statement of the amazingly small percentage of condemnations of these older cylinders. Pressure vessels, just like any technology are ungraded and replaced based on their suitability for the job and/or failure analysis, then there is cost of retro-fit. Everyone wants the smaller, lighter, less maintenance, higher volume PV's and the SCUBA industry is no exception. Do not exclude the marketing pressure for sales over suitability for the evolution.

Any pressure vessel made of any approved material, absent the related corrosion and damage, will last for centuries if it just sits there. However, once a pressure cycle begins which causes expansion/contraction, a process begins which will over time degrade the strength and elasticity of the material. That is why, in some applications, like aircraft - Some PV's will have a cycle limit or age limit {the age limit is imposed by the application for which it is used and having a high cycle rate projection and the cycles not logged}. Therein lies the need for the means to reliably test and manage of worlds inventory for the sake of safety and reliability.

And just to address the to dive with the extinguisher quip. Most that you could pickup and strap on of similar size to SCUBA are at most 2250, but usually 1800psi and low volume, and they have a different valves and neck thread - See CGA dedicated pressurize vessel and valve specifications - to prevent anyone from cross purposing or a wrong gas fill.

I think @Ana was being funny.

Good post however 100% correct and why I use the fire extinguisher testing facility rather than the LDS $20.00 per tank savings 8 tanks adds up quick. Other LDS bring their customers tanks there too. How do I know? Because their tanks are marked with their names. Ignorance is bliss and expensive sometimes.
Working 20 years in a shipyard around HP bottles and later hydro testing small piping systems taught me a little something. I've seen the old bottles too.

 

[Ana]

. The presumption that the testing is done by a "fire extinguisher" shop is somehow deficient lends to my conclusion that you don't understand the industry or the technology, and that if you were more informed would bring surprise to you. .

Thank you, I will try to become more informed because I love suprises.

.
IF you check with your LDS, in which you apparently have absolute confidence in, you will find that they do not have the facility to hydro-statically test any cylinder (pressure vessel) and they have to use a facility that does. l.

I will check one of these days for sure. On future posts I'll try to keep the appearances of my confidence a bit more clear.

 

[AfterDark]

I took steel a 72 and two 120s into their location in Riviera Beach a little over a year ago. I wanted air in the 72 for bridge diving and 32 in the 120s. They refused to fill the 72 saying "some old tanks are made of bad alloy". It appears as if they don't want to train the tank fillers the difference between aluminum and steel. They lost my business on all my fills. Since I'm not going in to get fills, I'm not browsing the shop for other things.

train the tank fillers the difference between aluminum and steel
You mean train them to use a magnet?

 

[Wookie]

IF you check with your LDS, in which you apparently have absolute confidence in, you will find that they do not have the facility to hydro-statically test any cylinder (pressure vessel) and they have to use a facility that does. Which means that their handling markup added to the vis and hyro cost they pay, drives your cost to more than $50. It costs hundreds of thousands of $ to open a facility with the equipment, personnel and warehousing space for thousands of cylinders cycled through from all the business using compressed gas and pressurized liquids.

This may be true in Tennessee, but in South Florida and the Keys, I know personally at least 4 dive shops that are also hydro facilities.

But please, do man'splain how hydros work.

 

[Squirm88]

This may be true in Tennessee, but in South Florida and the Keys, I know personally at least 4 dive shops that are also hydro facilities.

But please, do man'splain how hydros work.

Agree. My LDS in North Florida also has hydro facilities in house. $25 for a hydro.
Wakulla Diving Center Service

 

[AfterDark]

This may be true in Tennessee, but in South Florida and the Keys, I know personally at least 4 dive shops that are also hydro facilities.

But please, do man'splain how hydros work.

It's also true in RI and MA I do think however CT has a LDS with hydro testing facility. As a general statement it's accurate but not inclusive.

 

[Basking Ridge Diver]

But please, do man'splain how hydros work.

Hold my beer and watch this...