Jump to content

A Little Help? Any nuts and bolts experts here?


Recoil Rob

Recommended Posts

I'm rebuilding and modifying a 2004 Sealion boat trailer that was, and will be, used in salt water. Seems many of the original bolts were only zinc plated and not hot dipped, they're badly rusted and I need to replace them.
Is there a source for hot dipped Grade 5 bolts or am I dreaming?
I've tried all the online trailer specialists, I can find hot dipped U Bolts but not regular hex heads. They all sell SS hardware which is about twice the price and still not graded.
Any leads?

Link to post
Share on other sites

The above link is a good source.  You can look at 316 stainless fasteners.  They are the most corrosion resistant.  They are stronger than Grade 2 but slightly less strong than Grade 5.  Most trailer manufacturers use galvanized because of cost.  I have never seen stainless bolts that were graded.

 

Perk

Link to post
Share on other sites

Try Seattle marine supply, or Fshermens supply in Bellingham.  Grade 5 stainless can be found, never seen grade 8's,  A lot of non copper based never sieze on a grade 5 iron will take a ton of salt abuse before it can't be broken and replaced.   Or just grind the head off and replace every 10 years.  Since the nut and bolt trade went overseas it's all subjective anyway.

Link to post
Share on other sites

Fastenal is another source. I have ordered from McMaster in the past with good results.

 

A standard 316SST grade such as ASTM F593 GP2 CW  will show some corrosion over time depending on the amount of salt water exposure. Probably okay on your trailer. A more resistant grade of 316 SST would be ASTM A453 GRADE 660. We use Grade D which will likely be hard for you to find and expensive. ASTM A193, CLASS 2, GRADE B8M 316SST is going to be susceptible to cracking after longer term exposure to salt water.

Link to post
Share on other sites
3 hours ago, bigdog MN said:

Fastenal is another source. I have ordered from McMaster in the past with good results.

 

~ We use Grade D which will likely be hard for you to find and expensive.

 

Reactor? Not many applications require that type of hardware although pretty sure chemical in some situations does too. Been almost a half century since I went to Navy Nuclear Power School and have been out of the field for more than 25 years, since I retired from the Navy. They have added a lot of elements to the Periodic Table since then LOL. Although most are short lived and nuclear in nature. I used to deal with a lot of salt water at one time...

 

I've had good results with McMaster also but after I moved here first place I go is Fastenal. Bob Kierlin founded Fastenal in Winona, Mn. Corp HQ is still there. He donated some of his personal art to begin the Minnesota Marine Art Museum in Winona and is a founder there also.

Link to post
Share on other sites

I'd think twice about using SS fasteners on a mild steel boat trailer. When dipped in saltwater electrolysis will accelerate rust between the SS fasteners and the surrounding mild steel trailer frame causing the trailer frame to rust a lot more close to the SS fasteners.

 

Steve

 

Link to post
Share on other sites

I am not in nuclear, except on commercial side. We suggest ASTM A453 GRADE 660 Grade D for offshore SST bolting requirements and installations where bolts are required to meet NACE standards. Of course there are more corrosion resistant bolts but that is another topic.

 

The comment on galvanic corrosion is valid, there is a relatively large difference in potential between carbon steel and passive SST. However the trailer as anode is very large in mass (area) compared to a passive SST bolt as cathode, also assume the steel is painted providing another degree of separation, both of which should minimize corrosion of the trailer.

Link to post
Share on other sites

I would assume and hope that the trailer being for salt water is galvanized, at least the frame. Any galvanic corrosion would actually corrode (dissolve) the zinc before the steel because it has more negative potential and actually leave the steel alone. The Navy utilizes large zinc plates inside heat exchanges in the propulsion plants that have a high volume of salt water flow. As sacrificial anodes. Even smaller ships and boats use them around dissimilar metals when in salt water. I believe a trailer that gets dunked once in awhile in salt water would be OK to use Stainless fasteners on, as long as it is galvanized.

Link to post
Share on other sites

Thanks for all the leads.

After looking around it seems Fastenal is the only place that has Grade 5 hot dip but they are expensive, over $7 per on the 4x1/2-13.

I have decided against using Stainless as it's nearly as expensive and there is the galvanic corrosion issue.

The guy who picked up the phone at Bolt Depot was very helpful.

Looks like I'll spring for the hot dip and be done with it.

 


thanks,

 Rob

 

Link to post
Share on other sites

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now
×
×
  • Create New...