Quiz - Equipment - Dropped Scuba Tank

[scubadada]

one needs to understand what each investigation (visual & hydro) includes...

I would think that if there was any question about the degree of damage to the cylinder, apart from the valve, that the cylinder might undergo hydro as a result.

 

[rjack321]

For me there wasn’t enough info to go full hydro.

Agree
If there's a big gouge or dent then its going to be condemned from the VIP. If there's no big gouge or dent, then its going to pass and there's nothing changed about the tank metallurgically that requires a hydro.

 

[scubadada]

Agree
If there's a big gouge or dent then its going to be condemned from the VIP. If there's no big gouge or dent, then its going to pass and there's nothing changed about the tank metallurgically that requires a hydro.

This is more likely to happen with an AL cylinder than one of steel.

 

[rjack321]

This is more likely to happen with an AL cylinder than one of steel.

Aluminum is pretty easy to gouge, if you aren't careful you can create tiny gouges with a razor blade scrapping off stickers even. But the walls are crazy thick and dents are rare. The steel in steel 72s is tough to gouge but they have pretty thin walls and are a good example of a (relatively) easy to dent tank.

I am having a hard time imagining damage other than a dent or gouge. Bending the valve over and mangling the neck thread area perhaps? But that would fail VIP pretty obviously.

Welding cylinders get a ton of physical abuse (drops, rolls etc) and rarely sustain any visible damage, they also last through virtually indefinite hydro cycles if they don't rust first.

 

[saxman242]

Maybe it was covered in the DM course and I just forgot?

This one actually depends on where you get your info it seems...

The PADI DM book says:

"Besides at the intervals required by regulations, have a cylinder hydrostatically tested if:

• it has sustained a severe impact that could have damaged it"

However, the Encyclopedia of Recreational Diving is a bit less clear, it says:

"Although you have your cylinder visually inspected and pressure tested at intervals according to local dive community standards and regulations, you should also do so in case of possible damage such as:

• the cylinder has sustained impact damage"

 

[tursiops]

I dropped a 19 cuft pony and had to replace the DIN valve that went out of round. Visual inspection of the valve did not catch it, but (not) screwing in a DIN reg quickly did! A hydro would have missed it too....

 

[Pedro Burrito]

Spoiler: Answer

c. hydrostatic/pressure tested


I used to work at a dive shop in Virginia. Before I worked there, an employee was driving a pickup truck full of tanks back to the shop from the Millbrook quarry. He pulled out onto the road and got T-boned. He was hurt and the tanks were scattered. All of them had to be hydrostatically tested before they could be put back into service. I think there were 40 tanks, all aluminum 63s and 80s. The valves were all checked at the shop while the tanks were sent to the testing facility.

 

[rjack321]

That's a little more intense than falling off a picnic table or truck tailgate. So did any of them fail?

 

[scubadada]

Spoiler: Answer

c. hydrostatic/pressure tested


I used to work at a dive shop in Virginia. Before I worked there, an employee was driving a pickup truck full of tanks back to the shop from the Millbrook quarry. He pulled out onto the road and got T-boned. He was hurt and the tanks were scattered. All of them had to be hydrostatically tested before they could be put back into service. I think there were 40 tanks, all aluminum 63s and 80s. The valves were all checked at the shop while the tanks were sent to the testing facility.

Really? Dropped from a significant height, 3 ft, 4 ft, 5 ft? Please supply supportive citation.

 

[rjack321]

Really? Dropped from a significant height, 3 ft, 4 ft, 5 ft? Please supply supportive citation.

CGA guidelines don't have hard and fast numeric things like that in them. They articulate best professional judgment (and despite being incorporated into the CFRs by reference they are proprietary).