Underwater thread sealant?

I just got my new flexofold prop (which was once fitted briefly to a boat). The instructions I downloaded say the locking pin threads come with a special thread locking compound on them.

Of course they tell you that you must order new locking pins from flexofold just so you get the right compound on them. Otherwise regular compound will work if you haul out and fit it dry.

Does anyone know of a compound you can apply to a thread which then dries and is then suitable for installation underwater?

 

There is a glue or sealant sold by Mercury Marine for the installation of Mercruiser bellows. It is also called liquid neoprene, with toluene as a solvent. Once the solvent evaporates a durable flexible film is left.

 

Im not clear as to your application. Normal Locktight for the appropiate fastener diameter works fine underwater.

In some application ..stainless to stainless..thread galling can be a problem. Special threads lock that is a combo lubricant and thread lock is used. TuffGell is the brand I use.

http://www.tefgel.com/contain.php?param=tuffgel_infor

 

The application is that the thread sealant is to be used when fitting threads underwater. IE fitting a folding propeller while diving under the boat.

 

Oh...Ive never fitted a prop underwater.. Sounds like a crazy idea.

 

Of course you haven't. You just tell the rich owners to haul out. Its not like you are paying!

 

No...I do things correctly , then guarantee that the installation achieves full service life.

 

Micheal, the quote above was from the manufacturer who clearly states that underwater fitment is within the warranty guidelines as long as their secret thread compound is used. The whole point of this thread is to find out what this compound might be.

 

But if it's secret how would anyone else know?

Anyway, you can call loctite, I'd bet they make one (like #268 semi-solid). Or if you really want to do it properly, drill and pellet the screw.

Also try Nylok, they probably made the screws.

 

CDK. I tried to Google Liquid Neoprene but all I got were compounds to fix wetsuits?

jehardiman, I will look into #268 semi solid. What do you mean by drill and pellet the screw? Obviously I can use drills underwater.

Edit, looks like 268 wont do.

 

Here is the Mercury sealant:
http://www.michiganmotorz.com/mercruiser-bellows-adhesive-p-1098.html

I didn't get a clear picture from post #1, but now I see what you mean. They want you to buy new fasteners that are dipped in Loctite thread sealant so you don't have to buy the sealant separately and get sticky fingers.
That is not uncommon in today's industry; customers may not have sealant, don't know what it is, are unsure about the amount etc.

Frankly I cannot believe there is one Loctite, 3M, Sika or Henkell sealant that will dissolve in water, so I would clean the threads, apply a thin ring of flexible sealant and let it dry, then step in the water and hope you do not drop one.

 

Surely someone who is trying to fit a propeller to a yacht while diving in a murky marina is not scared of getting loctite on their fingers.

Their claim is that it is NOT normal loctite that comes on the threads for underwater fitment. They state you can use normal loctite when doing the job out of the water. However when doing the job underwater you cant use normal loctite as it obviously does not work underwater. If you apply regular loctite then let it dry first as you suggest it wont work as that is not how the product works.

I am trying to find a product that WILL work when used this way. This product seems to be a little bit special and harder to find. I hope this makes more sense now. I can not find directions on that bellows sealant will it go off and adhere underwater?

 

Pelleted fasteners are the professional way to avoid liquid or paste thread locks during assembly.

Various grades of plastic...heat resistant , oil resitant.....are used as the lock

A common supplier is http://www.nylok.com/

Many others.

http://www.apmselfsealingfasteners.com/news_threadlockers.asp

Pelleted nuts are widely available..... pelleted screws are hard to purchase in small quantities and hard to find in SS.

Locally I can only purchase individual pelleted fasteners in black steel and greater than 5mm diameter.

 

This is very confusing Dennis. Some industrial replacement packs come with brown or bue cured sealant on the fasteners. Not the whole thread is covered, just a 5-10 mm ring; during installation the stuff spreads of the whole length.

The bellows sealant does not contain isocyanate like Locktite, just a solvent. As far as I can remember there are no instructions on how long drying takes, but in that case it doesn't matter because nobody can do that job in 2 minutes, so the stuff will always have dried before the stern drive returns to the water.

 

For self-locking and anti-vibration blind applications the bolt/screw, in the area of thread engagement, perpendicular to the axis, a small blind hole is drilled. Into this hole a piece of nylon rod is inserted and trimmed off proud of the threads. When the screw is inserted, the nylon is compressed and the screw is locked. Generally the pellet is replaced every time you remove the bolt/screw.

http://www.sigmafasteners.com/catalog/section-10.pdf

That is probabilly a Nylok item. Most OEMs don't make or coat thier own bolts/screws, but buy them in bulk. Additionally, some of the sealant/lock coatings aren't brushed or dipped, but applied by plasma spraying so that they don't wear off and allow for moderate dissassembly.

http://www.nylok.com/