User avatar
SurfLung
Master Diver
Posts: 1324
Joined: Sat Jan 01, 2011 2:03 pm
First Name: Eben
Location: Alexandria, MN
Contact: Website

No VIP for Steel

Mon Jan 07, 2019 1:51 pm

No Visuals for Steel?
- Ron just called me after dropping his tanks off at Hydrostat, Inc. for Hydrotesting. It's a new place we're trying and Ron was surprised to hear that they do not do visuals for steel tanks. They DO perform this service for aluminum tanks.
- My understanding is that a Hydrotest has always included a rudimentary visual inspection as part of DOT requirements. This is the only visual required for welding and other cylinders and it is only required every 5 years along with the hydrotest.
- My question is this: Are annual VIPs for steel tanks simply an arbitrary rule that dive shops mandate? I know the VIP for aluminum is a Department of Transportation rule due to the SLC issue. But since steel tanks don't have SLC, is the annual VIP an actual LAW or an industry rule?
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

User avatar
ScubaLawyer
Master Diver
Posts: 1122
Joined: Thu Apr 08, 2010 11:25 am
First Name: Mark
Location: Laguna Beach, CA

Re: No VIP for Steel

Mon Jan 07, 2019 2:03 pm

SurfLung wrote:
Mon Jan 07, 2019 1:51 pm
No Visuals for Steel?
Are annual VIPs for steel tanks simply an arbitrary rule that dive shops mandate?
Yup.
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

User avatar
antique diver
Master Diver
Posts: 1723
Joined: Sun Dec 10, 2006 12:50 pm
First Name: Bill
Location: North-Central Texas

Re: No VIP for Steel

Mon Jan 07, 2019 4:57 pm

ScubaLawyer wrote:
Mon Jan 07, 2019 2:03 pm
SurfLung wrote:
Mon Jan 07, 2019 1:51 pm
No Visuals for Steel?
Are annual VIPs for steel tanks simply an arbitrary rule that dive shops mandate?
Yup.
Yes, and although I don't disagree with your policy on your own tanks you fill yourself, it may be a pretty good idea overall given that more not-so-bright persons (not you) may be filling Scuba tanks than are filling industrial and medical pressure vessels. Especially in the past before the potential dangers and proper safety measures were well publicized, maybe first by NASDS.

There is also the fact that Scuba tanks just stand a better chance of getting water into the valve because of where they are used compared to your average Oxygen, Nitrogen or Acetylene cylinder.

BTW... I know this is rare, but a few years back I acquired a nice steel cylinder with a recent hydro that actually had an ounce or two of water in it. Also four times in the past year I ran into air test failures for high moisture content in fire department storage cylinders that were recently hydro tested. Finally narrowed it down to a specific hydro test facility that all those departments had used. The cylinders had not been dried sufficiently before being placed back into service. That could happen with your Scuba tank being tested most anywhere on a bad day.
"I get plenty of excercise just pushing my luck!"

User avatar
luis
VDH Moderator
Posts: 1551
Joined: Thu Jun 30, 2005 9:28 pm
First Name: Luis
Location: Maine

Re: No VIP for Steel

Mon Jan 07, 2019 9:02 pm

SurfLung wrote:
Mon Jan 07, 2019 1:51 pm
No Visuals for Steel?
Are annual VIPs for steel tanks simply an arbitrary rule that dive shops mandate?
Yes and No.

Many years ago there was some testing done at Duke University were scuba tanks were added some water and then pressurized for different periods of time.

The water was to simulate the water that can be easily introduced by less than careful fill station operators doing wet fill. A common practice back then. Note: there are a number of ways to introduce water into a cylinder as Bill mentioned.

The results was that a cylinder that got contaminated with fresh water had a reasonable chance of being serviced (by tumbling) and saved if it was caught within a year’s time period.

BTW, the Duke test showed that if the contaminant was salt water (which I have seen it used for cooling water) the tank was beyond any possible service in about 3 months (as I recall). The test with salt water inside the cylinders had to be stopped because the pits were becoming too dangerous.

During the test the cylinders were actually placed in a reinforced bunker that they had available.

Contrary to common believe, VIP are not really intended to protect the fill station operator. That protection comes from the 5 year inspections and requalification. The VIP is really to protect the cylinder from being condemned. The yearly periodicity is intended to catch corrosion before it is beyond service potential.

The 5 year interval is normally good enough to catch a dangerous cylinder and take it out of service (by condemning it). But if you want to catch any issues early enough to save the cylinders then the yearly inspection is a better time lapse.

Note: I have a copy of the Duke University report. It is a large PDF file. But if I find it I will send it to Bryan to put it under the download section.
Luis

Buceador con escafandra autónoma clásica.

User avatar
luis
VDH Moderator
Posts: 1551
Joined: Thu Jun 30, 2005 9:28 pm
First Name: Luis
Location: Maine

Re: No VIP for Steel

Mon Jan 07, 2019 9:24 pm

SurfLung wrote:
Mon Jan 07, 2019 1:51 pm
No Visuals for Steel?
- My question is this: Are annual VIPs for steel tanks simply an arbitrary rule that dive shops mandate? I know the VIP for aluminum is a Department of Transportation rule due to the SLC issue. But since steel tanks don't have SLC, is the annual VIP an actual LAW or an industry rule?

The only aluminum cylinders that have SLC issues are the 6351 alloy cylinders. The use of that alloy was discontinued by 1989 (even earlier in some particular cylinders). And Catalina cylinders were never made of that alloy.

The DOT clearly classifies it as a defective alloy and has established a number of mitigation procedures to reduce the risk during the filling process.

Some of the risk mitigating steps include additional inspection (including visual eddy current testing), but also includes special precautions while filling (even after all the inspections).

Personally I just retired any of my cylinders of that alloy and I don't even hang around an LDS when they are filling a pre1989 aluminum cylinder. I have seen enough AL6351 cylinders with clear neck cracks that I just don't feel the need to take the risk (even if it is a small risk). Most cylinders with cracks due to SLC are being pulled out of service before any issues, thanks to the extra inspections. But why take the risk due to human error (missing an indication), etc.

There was a fellow I new in Cozumel that got killed filling a 6351 alloy aluminum tank just a few years ago.
Luis

Buceador con escafandra autónoma clásica.

User avatar
ScubaLawyer
Master Diver
Posts: 1122
Joined: Thu Apr 08, 2010 11:25 am
First Name: Mark
Location: Laguna Beach, CA

Re: No VIP for Steel

Tue Jan 08, 2019 1:08 pm

luis wrote:
Mon Jan 07, 2019 9:02 pm
SurfLung wrote:
Mon Jan 07, 2019 1:51 pm
No Visuals for Steel?
Are annual VIPs for steel tanks simply an arbitrary rule that dive shops mandate?
Yes and No.

Many years ago there was some testing done at Duke University were scuba tanks were added some water and then pressurized for different periods of time.

The water was to simulate the water that can be easily introduced by less than careful fill station operators doing wet fill. A common practice back then. Note: there are a number of ways to introduce water into a cylinder as Bill mentioned.

The results was that a cylinder that got contaminated with fresh water had a reasonable chance of being serviced (by tumbling) and saved if it was caught within a year’s time period.

BTW, the Duke test showed that if the contaminant was salt water (which I have seen it used for cooling water) the tank was beyond any possible service in about 3 months (as I recall). The test with salt water inside the cylinders had to be stopped because the pits were becoming too dangerous.

During the test the cylinders were actually placed in a reinforced bunker that they had available.

Contrary to common believe, VIP are not really intended to protect the fill station operator. That protection comes from the 5 year inspections and requalification. The VIP is really to protect the cylinder from being condemned. The yearly periodicity is intended to catch corrosion before it is beyond service potential.

The 5 year interval is normally good enough to catch a dangerous cylinder and take it out of service (by condemning it). But if you want to catch any issues early enough to save the cylinders then the yearly inspection is a better time lapse.

Note: I have a copy of the Duke University report. It is a large PDF file. But if I find it I will send it to Bryan to put it under the download section.
Agree with Luis. As far as a "rule" I am unaware of any state, federal or local statute, regulation or ordinance mandating annual VIP's for steel tanks. Happy to be proved wrong. :D
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

User avatar
SurfLung
Master Diver
Posts: 1324
Joined: Sat Jan 01, 2011 2:03 pm
First Name: Eben
Location: Alexandria, MN
Contact: Website

Re: No VIP for Steel

Tue Jan 08, 2019 2:33 pm

luis wrote:
Mon Jan 07, 2019 9:02 pm
SurfLung wrote:
Mon Jan 07, 2019 1:51 pm
No Visuals for Steel?
Are annual VIPs for steel tanks simply an arbitrary rule that dive shops mandate?
Contrary to common believe, VIP are not really intended to protect the fill station operator. That protection comes from the 5 year inspections and requalification. The VIP is really to protect the cylinder from being condemned. The yearly periodicity is intended to catch corrosion before it is beyond service potential.

The 5 year interval is normally good enough to catch a dangerous cylinder and take it out of service (by condemning it). But if you want to catch any issues early enough to save the cylinders then the yearly inspection is a better time lapse.
Thanks Luis... That makes perfect sense but it isn't what some Dive Professionals are leading sport divers to believe. I was just visiting with Rich (50,001 Questions) and he has had a dive professional tell him he's carrying a "bomb" on his back in reference to a tank that had just passed hydro but had some rust inside. The hydro operator had simply advised him he had some rust he should take care of ... Either looking for and removing the cause or just getting the tank tumbled to clean it up. Suggesting it was a "bomb" tells me the local professional maybe was not as knowledgeable about the cylinder re-qualification process as you would expect him to be.
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

User avatar
SurfLung
Master Diver
Posts: 1324
Joined: Sat Jan 01, 2011 2:03 pm
First Name: Eben
Location: Alexandria, MN
Contact: Website

Re: No VIP for Steel

Wed Jan 09, 2019 11:10 am

As It Applies To Vintage...
- Actually, with single tanks and standard 3/4 threaded valves, annual visual inspections are easy to do and since they are easy, its just good sense to go ahead and take a look inside whether the steel tank needs it, or is mandated to have it... Or NOT.
- The issue is really only a problem for us Vintage guys with single, twin, and triple tanks that are difficult and risky to remove the valves, disassemble the manifolds, re-configure the harnesses, etc. These are collectors items in many cases and repeatedly taking them apart and re-assembling poses a risk of damage every time you do it. Since we put these cylinders together ourselves, we are in the best position to know what they look like on the inside. I wonder if there is a way for us to take responsibility for it and have that be accepted by the dive shop? Kind of like antique cars get a different license plate.
- On the other hand, some of my vintage tanks have bushing valves and the dive shops won't fill them anyway... Regardless of whether I have a visual inspection sticker or not. It has turned out to be an easy thing to just fill these myself either by cascade from a tank filled by a dive shop or by just using my own compressor.
- Probably the only tanks I will need VIP stickers on this year will be the ones I bring to Sea Hunt Forever 2019... And even THERE... I'll be filling them myself via cascade cylinders in my car! :)
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

User avatar
antique diver
Master Diver
Posts: 1723
Joined: Sun Dec 10, 2006 12:50 pm
First Name: Bill
Location: North-Central Texas

Re: No VIP for Steel

Wed Jan 09, 2019 11:52 am

Maybe it's time to show this again. :shock:
why inspect.jpg
You do not have the required permissions to view the files attached to this post.
"I get plenty of excercise just pushing my luck!"

User avatar
luis
VDH Moderator
Posts: 1551
Joined: Thu Jun 30, 2005 9:28 pm
First Name: Luis
Location: Maine

Re: No VIP for Steel

Wed Jan 09, 2019 11:14 pm

SurfLung wrote:
Tue Jan 08, 2019 2:33 pm


Thanks Luis... That makes perfect sense but it isn't what some Dive Professionals are leading sport divers to believe. I was just visiting with Rich (50,001 Questions) and he has had a dive professional tell him he's carrying a "bomb" on his back in reference to a tank that had just passed hydro but had some rust inside. The hydro operator had simply advised him he had some rust he should take care of ... Either looking for and removing the cause or just getting the tank tumbled to clean it up. Suggesting it was a "bomb" tells me the local professional maybe was not as knowledgeable about the cylinder re-qualification process as you would expect him to be.


The training required to be a hydro station operator is not very extensive. They don’t have to be highly qualified technicians to perform the job.
But, on the other hand calling a pressure cylinder a “bomb” it is actually not that inaccurate from an energy point of view. I totally understand the point (and I agree) that there is no real need to make it sound dramatic. Just like I hate calling Scuba gear "life support System".

But a pressurized cylinder does contain the energy of a small bomb.

If you are referring to cylinder in good condition, with no rust or corrosion, and no other types of defects, a pressurized cylinder could be loosely equated to a “bomb” without any kind of a fuse.

If you are talking about a cylinder with rust, then it depends on how much rust. Very mild surface rust it would still be a “bomb” without a fuse.

If the rust is heavier and is holding some moisture then it could be loosely equated to a “bomb” with a slow fuse (or similar). Heavy rust or even medium rust (but how do you define that??) can hold moisture, which in turn is a catalyst for more rust and potential pitting.

These analogies are just loosely equivalents based on the potential energy stored in a pressurized cylinder.


BTW, on the subject of internal cylinder rust. I use a wire brush/ whip driven with an electric drill to remove any rust and I try to polish the inside of my cylinders with it. A clean polished steel surface provides less surface area to hold moisture and also less area exposed for rusting.


There is an easy test called a “hammer test” that is always supposed to be performed on all steel cylinders just before they are filled (but many fill operators are not aware of it). The test will give you an idea if there is excessive internal rust without actually looking inside.

All the test involved is lightly hitting the side of a steel cylinder with a small hammer or similar metal. A cylinder in good condition (with minimal or no rust) will sound clear as a bell.

If the cylinder doesn’t sound clear as a bell (it sounds dull), it is likely due to excessive rust and should not be filled without further investigation. I would not fill it.

Internal rust will dampen the typical sharp bell sound. I am sure everyone is familiar with the clear bell sound of a steel cylinder.

Note: this is only an extra indicator of the presence of rust and I have only notice the dull sound on a cylinder with a lot of rust.
Luis

Buceador con escafandra autónoma clásica.

User avatar
tripplec
Master Diver
Posts: 312
Joined: Thu Mar 28, 2013 1:44 am
First Name: Chris
Location: Coos Bay Oregon
Contact: Website

Re: No VIP for Steel

Thu Jan 10, 2019 10:28 am

Luis, what does the visual eddy test consist of? I had to pay a little extrs for thst on my last hydro and the lds put their ve stamp on it.

User avatar
luis
VDH Moderator
Posts: 1551
Joined: Thu Jun 30, 2005 9:28 pm
First Name: Luis
Location: Maine

Re: No VIP for Steel

Thu Jan 10, 2019 10:42 pm

Eddy current testing is used to detect discontinuities/ defects. In this particular case it is specifically looking for Sustain Load Cracks (SLC).

It only applies to cylinders manufactured out of aluminum alloy 6351. Take a look at my post about AL6351 above.

Take a look at this video.
https://www.youtube.com/watch?v=b0unxVF0k-k


Take a look at this link.
http://www.visualplus.net/


Eddy current testing is one of many types of Non-Destructive Testing (NDT) that has been used in some industries for a long time. In the Scuba and other pressure vessel industry (medical O2, etc.) a very specific testing device has been developed (by a couple of different manufacturers) to mitigate the issue that has developed with this alloy.
Luis

Buceador con escafandra autónoma clásica.

User avatar
tripplec
Master Diver
Posts: 312
Joined: Thu Mar 28, 2013 1:44 am
First Name: Chris
Location: Coos Bay Oregon
Contact: Website

Re: No VIP for Steel

Thu Jan 10, 2019 10:59 pm

I was curious about the actual testing process. Those links give the answere, thanks. I had one of the luxfers, I told my wife about the safety buletin on them exploding so she would think it was a good idea for me to spend the money on a new Faber.

Sent from my SAMSUNG-SM-J320A using Tapatalk


Return to “Tanks and Valves”

Who is online

Users browsing this forum: No registered users and 1 guest