Burst disk marking: working or bursting pressure ?

[Aquanaut]

Hi guys,
The LDS changed the burst disk for my steel HP100 tank (rated working pressure 3422psi) during hydro. It has a 3422psi marking on it and the LDS confirms that it’s the working pressure, NOT the bursting pressure. However, I’m still worried that it’s possible that they misplaced a disk that will burst at 3422psi and it will basically be refilled to its bursting pressure at every single refill…

As I searched online, some manufacturers mark working pressure on their burst disks while some put bursting pressure. For example, I have another steel HP100 tank with a valve that has 5250psi marking on it and clearly that’s the bursting pressure ..

Can someone who’s familiar with burst disks or have similar disks give me some advice so that I can get peace of mind ? Picture attached below, thanks in advance !

 

[Curious_George]

Google turned this up: LDS vs The Burst Disk.

 

[happy-diver]

Burst Discs - The Ignored Safety Device - Cylinder Training Services

 

[Aquanaut]

Google turned this up: LDS vs The Burst Disk.

Thanks, this is super helpful. One of the replies in this thread actually showed a similar burst disk marking convention. I’m more confident that the “3422 psi” marking is the working/service pressure.

 

[rjack321]

Hi guys,
The LDS changed the burst disk for my steel HP100 tank (rated working pressure 3422psi) during hydro. It has a 3422psi marking on it and the LDS confirms that it’s the working pressure, NOT the bursting pressure. However, I’m still worried that it’s possible that they misplaced a disk that will burst at 3422psi and it will basically be refilled to its bursting pressure at every single refill…

As I searched online, some manufacturers mark working pressure on their burst disks while some put bursting pressure. For example, I have another steel HP100 tank with a valve that has 5250psi marking on it and clearly that’s the bursting pressure ..

Can someone who’s familiar with burst disks or have similar disks give me some advice so that I can get peace of mind ? Picture attached below, thanks in advance !

You're good

there are no scuba tanks which are hydro tested at 3442psi, that would be like a 2065psi tank which don't exist. (there are some very vintage scuba tanks that were 1800psi but nothing that would ever have a rated pressure such that it would take a 3442psi rupturing disk)

 

[Fibonacci]

Very good idea to replace the burst disk, almost always overlooked!
Check that burst disk...

 

[Aquanaut]

You're good

there are no scuba tanks which are hydro tested at 3442psi, that would be like a 2065psi tank which don't exist. (there are some very vintage scuba tanks that were 1800psi but nothing that would ever have a rated pressure such that it would take a 3442psi rupturing disk)

Got it, thanks for the reassurance!

 

[Bob DBF]

In my experience, the burst disc assembly, which you have, is stamped with the service pressure, and an actual burst disc has the burst pressure stamped on it in ink. Also the old burst disc relief plug would not be marked, but the tank valve itself would usually has a tag with the service pressure of the tank on it.

 

[bletso]

All the industrial burst disks are marked with burst pressure. It makes it a math problem. Let's see is it 5/3 service pressure or 3/2's service pressure, (special permit cyls) But then again SP cyls generally have TP, (test pressure) stamped on them.

I just looked at a bunch of SCUBA valves, some with NO marking, sond some with TP and then some with service pressure... Go figure. At least in industrial cyls they are all marked with TP

 

[Tracy]

Unfortunately, the answer to your question is "It depends."
Some manufacturers mark both ways. That one is the service pressure as that would be a very uncommon test pressure.
To make it even more confusing, what it says on that outer nut has nothing to do with what disc may be installed underneath.
I change the discs every hydro, but I don't ever change that nut unless it is damaged. I do mark out the pressure if it reads incorrectly.