fastener locking methods....submerged in seawater
fastener locking methods....submerged in seawater
(OP)
I'm trying to make this short so if you need more info, please ask away.
We are putting a large unmanned buoy (200,000lb) in seawater and anchoring it to the seafloor. (Yes...I know that's stupidly difficult to do but it pays the bills). The only way to moor it correctly is to have the mooring line enter from the bottomside of the buoy through an intricate steel gimbaling system which allows for full range of wave motion.
Here's the question...
When bolting the joints(and other various parts) on the gimbal system, we cannot find a proven method for preventing the standard hex cap screws from possibly backing out(due to wave motion vibration) AND providing the galvanic isolation.
Goops like Loc-Tite don't make waterproof compounds and mechanical fasteners like Nord-Locks don't help with galvanic isolation so we're looking to combine the solutions. The structure is A588 steel and we are using Grade 5 hardware from McMaster.
The gimbal must be serviceable and replacable by divers under water since the bushings are wearing out yearly so the solution has to be reversably by divers with gloves on.
Does anyone have experience with Nord Locks, Vibra-Tite or anything else that may work for us?
bla...bla...bla...again....sorry 'bout the long question.
We are putting a large unmanned buoy (200,000lb) in seawater and anchoring it to the seafloor. (Yes...I know that's stupidly difficult to do but it pays the bills). The only way to moor it correctly is to have the mooring line enter from the bottomside of the buoy through an intricate steel gimbaling system which allows for full range of wave motion.
Here's the question...
When bolting the joints(and other various parts) on the gimbal system, we cannot find a proven method for preventing the standard hex cap screws from possibly backing out(due to wave motion vibration) AND providing the galvanic isolation.
Goops like Loc-Tite don't make waterproof compounds and mechanical fasteners like Nord-Locks don't help with galvanic isolation so we're looking to combine the solutions. The structure is A588 steel and we are using Grade 5 hardware from McMaster.
The gimbal must be serviceable and replacable by divers under water since the bushings are wearing out yearly so the solution has to be reversably by divers with gloves on.
Does anyone have experience with Nord Locks, Vibra-Tite or anything else that may work for us?
bla...bla...bla...again....sorry 'bout the long question.





RE: fastener locking methods....submerged in seawater
Mike Halloran
Pembroke Pines, FL, USA
RE: fastener locking methods....submerged in seawater
Mike Halloran
Pembroke Pines, FL, USA
RE: fastener locking methods....submerged in seawater
RE: fastener locking methods....submerged in seawater
Have you looked at "Stage 8"s?
http://www.stage8.com/howitworks.htm
Mike Halloran
Pembroke Pines, FL, USA
RE: fastener locking methods....submerged in seawater
It's not out of the picture though....
RE: fastener locking methods....submerged in seawater
TTFN
RE: fastener locking methods....submerged in seawater
Mike Halloran
Pembroke Pines, FL, USA
RE: fastener locking methods....submerged in seawater
RE: fastener locking methods....submerged in seawater
If you're contemplating serious changes, you might look to reducing the number of fasteners and increasing their size. I'm imagining that your divers might prefer to work with a few large castellated nuts, locked with cotter pins.
Better yet, ask your divers to participate in the development effort. They'd probably like a few days in a warm dry office.
Mike Halloran
Pembroke Pines, FL, USA
RE: fastener locking methods....submerged in seawater
Thanks.
RE: fastener locking methods....submerged in seawater
As a design solution, it has the big advantage that the spares are cheap, so you needn't feel guilty about losing the odd pin as you're trying to fiddle it into the hole.
Being able to assemble onto a set of fixed studs rather than having to line up two sets of holes while buoy, gimbal and diver are all dancing randomly around one another is an added bonus. I get the impression you aren't planning to do this job in a nice sheltered non-tidal lock?
A.
RE: fastener locking methods....submerged in seawater
RE: fastener locking methods....submerged in seawater
RE: fastener locking methods....submerged in seawater
A.
RE: fastener locking methods....submerged in seawater
Sort of like a roller chain vise on a larger scale...
Mike Halloran
Pembroke Pines, FL, USA
RE: fastener locking methods....submerged in seawater