3/8" vs 5/16" bolt?

[Jaeger45]

I've got to say, for a hardware thread, this has become quite entertaining. Thanks, everyone!

 

[captain]

I've got to say, for a hardware thread, this has become quite entertaining. Thanks, everyone!

Amazing what 1/16" of an inch can do.

 

[WVMike]

Diverite 7.25 inch bands come with 5/16 bolts. I found with the 3/8 bolts your spacing has to be pretty precise to fit the holes in Halcyon back plates at least.

Good tips, good thread, thanks everyone.

 

[Leadking]

I have had nothing but trouble with stainless bolt/nut combinations due to galling. Too many times I have had to torque and snap the end of the bolt off just to get it apart when the nut was seized. I always use hot-dipped galvanized hardware on my bands now.

The reason ss galls is usually due to debris in the threads. SS does not dissipate heat very well and when debris is encountered the friction will literally melt the metal. Cleaning and lubricating the threads before installing or disassembling will eliminate the problem.

 

[WVMike]

The reason ss galls is usually due to debris in the threads. SS does not dissipate heat very well and when debris is encountered the friction will literally melt the metal. Cleaning and lubricating the threads before installing or disassembling will eliminate the problem.

What do you use to lubricate?

 

[WVMike]

SS galls pretty easily, you need to use lube eg blue moly

Would this be the product you recommend?

Bostik Blue Moly Anti Seize - Industrial Supply Group

 

[Leadking]

any anti-sieze will work, even wax will work.

Here is a good site for info;
Stainless Steel Galling / Locking Up / Freezing Up

 

[duckbill]

The reason ss galls is usually due to debris in the threads. SS does not dissipate heat very well and when debris is encountered the friction will literally melt the metal. Cleaning and lubricating the threads before installing or disassembling will eliminate the problem.

Yea, thanks for this and the link, but I think the information is wrong. But, who cares? I could be wrong too. I really do appreciate your willingness to help though.

I believe galling is caused when two similar metals with similar hardnesses rub past eachother. Neither surface will "give" more than the other, so they "give" equally and the imperfect surfaces of the metal interlock. I don't think it has anything to do with "protective oxides (being) broken, possibly wiped off", as stainless typically has far less of an oxide layer than either brass or pure steel, neither of which are known for galling.

Also, it seems to me that galling produces heat, not the other way around, since once the surfaces start to interlock they are producing tremendous friction, enough to seize the parts eventually. Only certain metals seem to have the tendency to gall and seize. Galvanized parts seem to have some inherent "lubricity" and they don't gall. If heat causes galling because it "melts the metal", then galvanized parts would seize horribly as zinc melts at a much, much lower temperature than stainless. The threads can be perfectly clean and be threaded as slowly as possible, but they will still gall.

Lubricant seems the best way around the problem if you insist on using stainless hardware, but I use the hot-dipped galvanized hardware so I never have to worry about nuts seizing when I go to disassemble my bands. I'm done spending money on expensive stainless that I have to break to get apart, only to have to buy more expensive stainless parts, when galvanized is cheaper to begin with and I have yet to have my original hardware rust or seize on me after all these years.

The only downside I have seen from using the galvanized on stainless bands is that the zinc will tend to "frost" or stain the stainless surrounding it. But that doesn't bother me since the stainless bands are doing the same thing to my galvanized tanks. I would that all my bands were galvanized steel rather than stainless for just this point alone though.

 

[captain]

Yea, thanks for this and the link, but I think the information is wrong. But, who cares? I could be wrong too. I really do appreciate your willingness to help though.

I believe galling is caused when two similar metals with similar hardnesses rub past eachother. Neither surface will "give" more than the other, so they "give" equally and the imperfect surfaces of the metal interlock. I don't think it has anything to do with "protective oxides (being) broken, possibly wiped off", as stainless typically has far less of an oxide layer than either brass or pure steel, neither of which are known for galling.

Also, it seems to me that galling produces heat, not the other way around, since once the surfaces start to interlock they are producing tremendous friction, enough to seize the parts eventually. Only certain metals seem to have the tendency to gall and seize. Galvanized parts seem to have some inherent "lubricity" and they don't gall. If heat causes galling because it "melts the metal", then galvanized parts would seize horribly as zinc melts at a much, much lower temperature than stainless. The threads can be perfectly clean and be threaded as slowly as possible, but they will still gall.

Lubricant seems the best way around the problem if you insist on using stainless hardware, but I use the hot-dipped galvanized hardware so I never have to worry about nuts seizing when I go to disassemble my bands. I'm done spending money on expensive stainless that I have to break to get apart, only to have to buy more expensive stainless parts, when galvanized is cheaper to begin with and I have yet to have my original hardware rust or seize on me after all these years.

The only downside I have seen from using the galvanized on stainless bands is that the zinc will tend to "frost" or stain the stainless surrounding it. But that doesn't bother me since the stainless bands are doing the same thing to my galvanized tanks. I would that all my bands were galvanized steel rather than stainless for just this point alone though.

From a galvanic corrosion perspective galvanize bands and bolts would be the best choice on galvanized tanks with stainless bands and isolation material between the bands and tank second and third would be stainless or aluminum directly against the tank.
Years ago before the removable back pack both single and double tanks were sold with galvanized bands and and bolts and harness so there was no need move bands to other tanks. Now single tanks don't have permanently installed bands but doubles do in most cases.
The down side to galvanize is they aren't pretty or expensive.

 

[duckbill]

The down side to galvanize is they aren't pretty or expensive.

I just wish they were still available:depressed: