Common Hydro Failure?

[SarahBella]

I was talking to the owner of an LDS the other day about which tanks would be a good investment when he told me the most common type of tank that fails Hydro is a high pressure tank. Anyone ever heard this? I am not sure if this was his personal experience or if it was based on some statistic but I alway thought tanks would last many years if they were taken care of regardless of the pressure.

[fireflock]

What kind of tanks was he selling?

I'm far from an expert on the subject, but I think some of the 3442 series tanks have a slightly different hydro procedure than others. I've heard of facilities using the wrong procedure and failing those tanks when they likely would have passed using the correct procedure.

Hopefully someone with more details can chime in.

Rich

[in_cavediver]

The only tanks I have seen/heard fail more often is the older 3500psi high pressure tanks. Comudude I believe has had one or two fail. One of my buddies has 1 fail. (first hydro too)

Most of the common 3442 tanks are just now coming due for thier first hydro so I doubt there is a wealth of data for them. (PST introduced them in 2003)

[Puffer Fish]

Originally Posted by in_cavediver

The only tanks I have seen/heard fail more often is the older 3500psi high pressure tanks. Comudude I believe has had one or two fail. One of my buddies has 1 fail. (first hydro too)

Most of the common 3442 tanks are just now coming due for thier first hydro so I doubt there is a wealth of data for them. (PST introduced them in 2003)

We are coming up on the time where the first of these chrome Moly tanks will get Hydro'd. Will be very interesting if someone has done that with one of the 3442 tanks...(as I have a bunch)

[marchand]

Strange, I have three of the old 3500psi tanks made by PST in 1991 and they just passed their third hydro.

It may actually be true because there is really no difference between the HP and LP tanks, but during hydro they are both filled to 5/3 of their working pressure. This means that the HP tanks get filled to ~5800psi during hydro while the LP tanks are only filled to ~4000. Even thought the tanks are essentially the same the HP tanks are under more stress than the LP tanks during use, and under even more when they are hydroed.

[cummings66]

If there really is no difference then why does the LP version of the tank weigh MUCH more than the HP version?

[texdiveguy]

The true question to be asked is how many pass the VIP after passing the hydro, this is really were the true test is.

[Puffer Fish]

Originally Posted by cummings66

If there really is no difference then why does the LP version of the tank weigh MUCH more than the HP version?

You have to compare equal volume (internal volume) and not capacity. Have not actually done that, so I don't know.

The new generation of hp tanks (the worthington and Faber XF) are a very different alloy, one that should be much stronger and not have any issues (the XF I have are thru their second visual and they don't even have flash rust in them). But "should" and "Don't" is sometimes very different.

[marchand]

Because a LP120 is designed to hold 120cf at 2640psi while a HP120 is designed to hold 120cf at 3500/3442psi. A LP120 is really a HP160 if you can get cave fills.

[SarahBella]

I had no idea a little question would kick off such a discussion-thanks for the input.