Re: [PSUBS-MAILIST] Ballast Tanks

Hi Dan,

Thanks for the comments, I think.

My tanks are built from heavy steel and forged endcaps 1/2 inch thick both of which have a working pressure of 1000 PSI. I was really testing my welds and since my ballast tanks are inside felt that if there was a failure it would be much less destructive in the shop.

I will need slightly less than 500 psi working pressure maximum. The next lower tubing would have made it there just barely. I felt that in the event that my internal coating was not successful and I had corrosion over the years that the extra strength would buy be much more time by over building the tanks.

I also need the weight so I felt it was a good place to use some.

Best Regards,

Jim K

htes t konl nare woHeavy

----- Original Message -----

From: Dan H.

To: personal_submersibles@psubs.org

Sent: Friday, November 21, 2008 7:12 AM

Subject: Re: [PSUBS-MAILIST] Ballast Tanks

Damn Jim, 1200 PSI, in a welded tank!!!!!!!!!

If you tied that tank to your motor cycle and the end cap blew, even you couldn't do the ride. No need to test much over what the tank will be used for, just to see if you have a leak. Testing to destruction can be VERY destructive.

One note on the subject of using pressurized fluid to test a container.

Be sure to fill it totally with water and avoid any air pockets to minimize the energy stored. But, even full of fluid, it can cause a lot of damage if it fails. There's considerable energy stored in the steel as it expands, even a little bit, under high pressure.

Jim, you already got all the BRASS you need to test dive your sub. ;-)

Be careful, Dan H

----- Original Message -----

From: Jim Kocourek

To: personal_submersibles@psubs.org

Sent: Wednesday, November 19, 2008 7:57 AM

Subject: [PSUBS-MAILIST] Ballast Tanks

Hi Dan H,

Thanks again for the tip on using pressure washer for pressure testing. I only have completed testing one so far, but at 1,200 PSI no pinholes and no endcaps blowing off.

I did have some leakage at the threads, but they are deformed from welding and I have not finished taping them because I wish to coat the inside with epoxy prior to getting cutting oil contamination on the inside surfaces.

I did have one funny screw-up. I for got to put a blow-off valve to relieve the pressure so I guess I'll have to carefully partially loosen a fitting and allow it to bleed down as the quick couplers will not uncouple with pressure inside.

Best Regards,

Jim K