Burst Disks - periodic replacement?

[mheaster]

I had five aluminum tanks in for annual viz and fill and since I have owned them for 10+ years, (I have maintained Hydros) I asked specifically to have the burst disks changed. Isn't this reasonable?

When I picked them up yesterday, I was told there is no way to "test" or "Inspect" the burst disks and if they are ok they should be left alone!

I was a bit put off, as I operate on the business assumption, that the customer is alway right and when they are not, they are still always the customer! I certainly expected to pay the cost of the new burst disks (I assume they can not be that expensive?) and the Dive SHop Operator's/Owner time to install.

Should I be pissed?

 

[DeepSeaExplorer]

Perfectly reasonable! Don't be pissed... Just take them back and insist they be changed. Explain that they're old and you want them replaced as a preventive measure. I consider this especially important if you're overfilling or diving in overhead.

Bust disks will dimple so you can't inspect them. If you open them up, they should be replaced.

 

[do it easy]

I replace my bursts disks every year when I O2 clean my tanks and valves. For air tanks, I would probably let it go a little longer. I think the general practice is to replace the burst disk if they are removed.

Depending on the style, I think burst disks are usually less than $10. Of course this will add up with multiple tanks.

 

[miketsp]

Well testing burst disks is a bit like testing matches.
And once removed they should be replaced.
However your request to replace them is perfectly reasonable in part based on the argument that each time you stress them by filling and emptying the tank they will get a little more fatigued and eventually fail. Plus all materials suffer some corrosion and consequential weakening.
OTOH if they are working within their elastic limit and are well seated with no irregularities causing stress points then they should last the life of the tank. Also there are some threads on SB where posters have reported bad lots of replacement disks on the market and have had repeated failures after replacement.
Personally I'd be inclined not to touch them on a yearly basis but do what you are doing say each 5 or 10 years.

 

[DA Aquamaster]

Over the last 20 plus years of diving I have seen perhaps 3 or 4 burst discs fail on my tanks. Fortunately, all have failed during the filling process, which is also not surprising as it is by far the most likely time for an old burst disc to fail.

On one hand you can view this as a very low probability of failure with an even lower probability (almost non existant) that they will fail during a dive.

On the other hand you can view this extremely low probability as still having the possibility of causing you a really bad day, or at least a major inconvenience. In keeping with that thought, when I started technical diving I started replacing the burst discs each time a tank is hydrotested (or in the case of a re-valved or manifolded tank, when the valve or manifold reached 5 years of age.)

So in my opinion, periodic replacement at hydro is never a bad idea. It's probably a good idea if you engage in some form of diving in soft or hard overhead environments, but could also be considered overkill and a waste of money for recreational diving.

Either way, it should be the diver's choice and given that changing a burst discs takes perhaps two minutes when the tank is already de-valved, there should be minimal objection from a hydrotester or visual inspector. If they are so time strapped that the extra couple minutes is a problem, I'd seriously question the quality of their inspection services.

 

[Isaac-1]

Just a couple of points, it may be possible that they did not have any burst disks in stock to fit your brand/model of valve and since it is not common practice to change them they did not do it. Dive shops sometimes get some odd request when it comes to repair mostly from customers that don't know what they are talking about (not saything this is the case this time). As to burst disks failing in the water I can remember seeing it happen twice in my 20 years of diving, once was an instuctor candidate at my IE, his blew on the surface within 10 minutes of entrering the water (the water plume looked like a whale blowing). The other time was far more worrysome, as it happened at about 80 feet down on a wall dive 10-15 minutes into a dive, I was about 30 feet away and 10-15 feet above the diver it happened to.

Ike

 

[idive2]

I had a four year old AL80 burst disk fail during a fill about a year ago.
I was with the shop owner in front as the tank was filling when the disk
went. It blew two ceiling tiles from the ceiling, a wetsuit off a rack onto the compressor and nearly into the pulleys. If I remeber correctly it appeared there
was some whip hose or fitting damage to his equipment. If I was a shop owner
I don't think I would object to a request for a new burst disk.

 

[in_cavediver]

I had a four year old AL80 burst disk fail during a fill about a year ago.
I was with the shop owner in front as the tank was filling when the disk
went. It blew two ceiling tiles from the ceiling, a wetsuit off a rack onto the compressor and nearly into the pulleys. If I remeber correctly it appeared there
was some whip hose or fitting damage to his equipment. If I was a shop owner
I don't think I would object to a request for a new burst disk.

This sounds like more than just the disk letting go. The idea of the burst disk is to release pressure in a non-directional manner. No damage to any equipment should have occured.

Now if it was an old plug style that not used anymore, that would be a different matter.

 

[DiveGearExpress]

This sounds like more than just the disk letting go. The idea of the burst disk is to release pressure in a non-directional manner. No damage to any equipment should have occured.

Now if it was an old plug style that not used anymore, that would be a different matter.

We have seen enough burst disks blow, and can assure you, that when one lets go, even a non-directional disk, it will fly the cylinder around on it's fill whip like a kite. There are plenty of dents on our main fill panel (made from stainless steel) to prove this.

2 days ago, we had one let go on a HP 100, with a Thermo valve (non-directional disk.) The clyinder whipped around, knocking all the other cylinders over, then smashed and destroyed our main pressure gauge.

We can assure you, we hate when this happens. It is unsafe, causes damage, and scares the heck out of anyone who happens to be in the shop. It takes just a second to change most burst disks, and if anyone asks us, we gladly do it.

 

[pickens_46929]

My LDS has a policy that burst disks get changed during your Viz. Period. For all the reasons outlined above and for that fact that this is one of those rare times (supposedly) that your tank is completely drained of air and you can actually replace the little buggers.