Sheave Bushing for Subsea Application
Sheave Bushing for Subsea Application
(OP)
We are currently designing some sheaves that will be submerged in seawater for extended periods of time. We wish to make the sheaves and pins from stainless steel, however what is the best material to use for a bushing?
We think that brass or bronze against stainless in seawater will cause problems. Is this the case?
The sheaves will have a conventional grease system to lubricate between the bushing and pin.
We think that brass or bronze against stainless in seawater will cause problems. Is this the case?
The sheaves will have a conventional grease system to lubricate between the bushing and pin.





RE: Sheave Bushing for Subsea Application
Depending on your particular application, you might want to consider AL6061-T6 for the sheave material. The pins should remain stainless steel.
RE: Sheave Bushing for Subsea Application
I agree, some sort of plastic is the obvious bearing material, I'm a bit leary of aluminium in sea water - it is better than magnesium (plink plink fizz) but if it ever comes in contact with another metal it'll dissolve.
Pick your SS carefully - 304 is not really suitable, and make sure you get it from a reputable supplier, not all 316 ss is equally suitable.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Sheave Bushing for Subsea Application
As for service, it will be very intermittent and will be submerged almost constantly apart from diver bell runs (return to swap divers at end of 12-hrs, etc)
As it is a clump weight we need the structure to be heavy, so I think best we choose stainless 316 for the sheave material.
Would delrin be subject to swelling in seawater, as nylon is?
RE: Sheave Bushing for Subsea Application
Greg is correct - with aluminum you do need to be careful for any galvanic reactions. It all depends on what will be around it. Stainless is a fine choice.
RE: Sheave Bushing for Subsea Application
With delrin, you can confirm that no lubrication is required? Even for faster applications?
RE: Sheave Bushing for Subsea Application
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Sheave Bushing for Subsea Application
http://en.lewmar.com/home/index.aspx?page=home
http://www.harken.com/blocks/blocks.php
I'm sure they could help you.