Fastener material/ coating for application with KCL

[ARenko]

We have some equipment installed under the rig floor on a drilling rig where KCL mud is used. We are adding a carbon steel cover to add some protection from impact and this cover will have to be periodically removed for servicing the equipment. There's concern that corrosion of the fasteners preventing removing the cover when it's necessary to service the equipment. We intended to use weld nuts on the back side of a carbon steel plate that the cover will bolt onto. What would be suitable materials and/ or coatings for the nuts and bolts in this application?

 

[MJCronin]

IMHO, These fine people wrote the book on corrosion resistant bolt coatings ...

https://www.whitfordww.com/brands/xylan-industrial/

Contact them and tell us about your final decision

Please keep us in the loop .....

MJCronin
Sr. Process Engineer

 

[TugboatEng]

The automotive industry has gone to an aluminum-zinc formula to resist road salt. They're available through your industrial supply companies such as McMaster-Carr or Kimbal MW. Armorcoat is one brand name.

Otherwise your 316 stainless fastener is the go-to. They tend to gall up if you remove and install them a lot. I put Nitronic 60 helicoil inserts in my last installation. It was a high temp application and I didn't want to rely on anti-seize.

 

[ARenko]

Thanks for the replies. I'll go with the Armorcoat so we don't have to worry about galling.

 

[EdStainless]

The other option is a metallic Ni-Co coating.
ASTM B994

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P.E. Metallurgy, Plymouth Tube

 

[cap1a79]

If the facility is protected by CP system, the coating shall not be zinc as there is mechanism of hydrogen embrittlement where hydrogen is possibly trapped in confined space around cathode. ( Nowadays, zinc coating is being ruled out for bolt especially when CP is applied (ex. offshore or sub sea, even underdround)
Refer to below link. It is a failure report related to hydrogen embrittlement.

https://www.corrosionpedia.com/hydrogen-embrittlement-issues-with-zinc-new-guidance-discussed/2/1822

Lee SiHyoung,
WorleyParsons Oman Engineering,

 

[TugboatEng]

Cap1a79, this application sounds like the bolts are used to hold a cover in place. Stress will be minimal. The portions of the structure above the waterline will not be affected by, I'm assuming, cathodic protection if that's what you mean by CP.

 

[ARenko]

It's onshore and under the rig floor of a drilling rig, where occasionally some KCL mud can rain down on it. And like TugboatEng said, it's low stress - the cover weighs about 30 lbs - it's just to protect a part of the equipment during transport/ handling/ installation.

 

[cap1a79]

Ok. Arenko. Forget my comment. It is only for the case when external CP current is applied (especially for over protection). I would agree to use zinc coating for your usage related to the cover contacting with rain water.

Lee SiHyoung,
WorleyParsons Oman Engineering,

 

[Harry.]

Hi,

I've come across this post because I'm looking for some corrosion resistance answers about 316 screws.
I'm attaching some plates to mounting brackets on boats. Its made from ss 316. We are attaching them with 316 fasteners which are proving difficult to install because of galling, but my customer is wanting ss 316 because its less likely to corrode. If I use 314 stainless, it's not 'Marine Grade' but will it really make that much corrosion difference? I don't want the screws to come loose over time and their plates to come off.

Thanks

 

[EdStainless]

Harry,
How about starting a new thread?
That said search this site for 'stainless''anti-seize'.
And you know that you will get crevice corrosion is salt water if you bolt two 316 items together?


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P.E. Metallurgy, Plymouth Tube