Avoiding thread galling on thru-hull/ball valve

[Daverw]

About 1mm thread depth sounds about right if your measuring thread ID and OD

 

[coopec]

About 1mm thread depth sounds about right if your measuring thread ID and OD

Absolutely spot on!

I know it was a stinking hot day (41° C/106°F) so I probably wasn't at my best but that fact escaped me!

41.9mm-39.6mm = 2.3mm thread.

As it is 38° C already I'll try to fit it again tomorrow.

Thanks!

 

[ghostlymoron]

When installing some large SS anchor bolts we had a couple of incidences of galling. Our metallurgist recommended using anything containing lanolin so we used Boots lanolin hand cream and had no further problems (and also very soft hands).

 

[Rum Run]

Yesterday I got down in the bilge and with my knees up near my ears I tried to fit the ball valve on to the thru-hull but I failed.

I checked the O/D of the thru-hull with the digital vernier gauge and found it was 41.9mm.
I then checked the I/D of the female thread opening of the ball valve and found it was 39.6mm

I'll try again today but has anyone got advice?

That is ok for 1 1/4" BSP assuming you measured across the inside of the female thread.
PTFE tape is good too.

 

[coopec]

316 definitely is susceptible to galling along with most 300 series stainless steel. As said, MoS2 products have been shown to provide the best resistance to the problem although people will claim that Copaslip is equally good.

I wonder whether Molybdenum Disulfide grease qualifies as a "MoS2 product"

• Molybdenum disulphide blend
• Increased shock load protection for ball and Constant Velocity (CV joints)
• Preferred grease for wet and high dust applications

Kincrome ‘Moly’ High Performance Grease is an extreme duty, high temperature grease. It contains a blend of extreme pressure additives and molybdenum disulphide, formulated to provide the best shock load protection for automotive ball joints and constant velocity (CV) joints. This grease has excellent adhesion characteristics, which remain stable under heavy loads, is water resistant, oxidisation, and corrosion resistant and is the preferred lubrication for wet and high dust applications including mining.

Kincrome 450g Moly High Performance Grease

 

[vyv_cox]

I wonder whether Molybdenum Disulfide grease qualifies as a "MoS2 product"

• Molybdenum disulphide blend
• Increased shock load protection for ball and Constant Velocity (CV joints)
• Preferred grease for wet and high dust applications

Kincrome ‘Moly’ High Performance Grease is an extreme duty, high temperature grease. It contains a blend of extreme pressure additives and molybdenum disulphide, formulated to provide the best shock load protection for automotive ball joints and constant velocity (CV) joints. This grease has excellent adhesion characteristics, which remain stable under heavy loads, is water resistant, oxidisation, and corrosion resistant and is the preferred lubrication for wet and high dust applications including mining.

Kincrome 450g Moly High Performance Grease

Perhaps a lower loading of MoS2 than a purpose made anti-galling product?

Years ago when working in research a colleague was a member of a multi-industry team investigating the problem. They found MoS2 to be the best palliative and for a time Shell produced a product for the duty. Production was sold off to a specialist company.

 

[coopec]

I've been trying to find MoS2 in a suitable sized package (250ml) but you have to be so careful. There are US products e.g. Bostik but the postage costs more than the product . (They want to sell you 8oz anyway)

I thought I had found exactly what I wanted (Molytec) but reading the description there is no MoS2 in it.



I avoid buying Loctite products because (rightly or wrongly) I believe they are overpriced. But their anti-seize doesn't contain MoS2 anyway.

I think I'll stick with Molybdenum Disulfide grease that I mentioned above. That with X4 layers of Teflon thread tape will surely stop any galling?

.

 

[vyv_cox]

Looks like that's your best option. The Shell product was a heavy grease, a trowelling grade rather than brush.

 

[coopec]

Looks like that's your best option. The Shell product was a heavy grease, a trowelling grade rather than brush.

The Kincrome grease is Grease Viscosity NLGI 2

"What does NLGI #2 mean?

NLGI Grades 1-3

"The most commonly used greases, such as those used in automotive bearings, would use a lubricant that is NLGI grade 2, which has the stiffness of peanut butter."

Thanks for your help

 

[vyv_cox]

The Kincrome grease is Grease Viscosity NLGI 2

"What does NLGI #2 mean?

NLGI Grades 1-3

"The most commonly used greases, such as those used in automotive bearings, would use a lubricant that is NLGI grade 2, which has the stiffness of peanut butter."

Thanks for your help

Viscosity increases with the number. Grade 3 is very heavy indeed, I have a tin of water pump grease in Grade 3. It is quite difficult to push a knife through it. I have seen this grade compared to 'frozen yoghurt' but I have never seen any of that! I think the Shell grease was probably between 2 and 3.