Strength of PVC framing

[superarp]

Has anyone used PVC to frame an ROV that goes deeper than 200 feet? How was it done

[derelicte]

if you drill holes in the pvc so that water can enter (often called a wet frame), then the pvc will be fine for really deep depths.

even if you don't drill holes, the max working pressure of 1/2" schedule 40 pvc is about 300 psi, which would be about 600'. the bursting pressure is significantly higher.



http://www.engineeringtoolbox.com/pvc-c ... d_796.html

[superarp]

So basically PVC is awesome??? Thanks

[Kjetil]

Burst pressure is the inside pressure, when you are using PVC pipe in water you need to worry about collaps pressure (Outside pressure). You have 1 bar (14,5 PSI) air pressure inside and for 200 meter (660 ft) of seawater depth you will have (1.03X0.0981X200) 20 bar (290 PSI) on the outside. I do not know the collaps pressure for the pipe, but it will be different compared to the burst pressure.

[derelicte]

while that is technically correct, there doesn't seem to be much of a difference for our purposes.

for example, look at this chart which shows the collapsing pressure for cpvc (I couldn't find one for pvc in the two minutes I spent looking):



the burst pressure and collapse pressure for 1/2" sch 40 are about the same (1900 vs 1600).

from here:
http://www.engineeringtoolbox.com/cpvc- ... d_240.html

[PSCG]

But what about the PVC glue? As i've seen, it is only rated up to 16 atm (16 bar, 235 psi) and if i'm correct, it will not survive that kind of pressure the PVC pipes can.

Τruly, the PVC pipe is realy amazing if you think that 600 psi equals to about 400 m depth (1312 ft).

[derelicte]

That is another good point. I found ratings for different glues and the burst pressure was stated at 400 psi.

That is still pretty deep, especially for our purposes.

This company lists the burst pressure for their glues.

http://www.e-zweld.com/products/product ... d=MTA0Mg==