Galling threads
Galling threads
(OP)
I am threading an endcap onto a cylinder- it will be a core sampling instrument. The endcap will take a some large impact loads, so needs to be a strong and tough material. The machine will operate in a marine environment, so 17-4-h900 is the preferred material. the cylinder will be 304SS schedule 80 pipe.
Will this combination lead to a galling problem with the threads? The threaded joint will be made and unmade each time a sample is taken.
I have had some serious issues with stainless galling- especially 316 to 316 joints.
thanks in advance!
Will this combination lead to a galling problem with the threads? The threaded joint will be made and unmade each time a sample is taken.
I have had some serious issues with stainless galling- especially 316 to 316 joints.
thanks in advance!





RE: Galling threads
Likely yes. The PH alloys don't offer much more gall resistance than the standard 300 series alloys.
A Nitronic alloy, say Nitronic 60 or 32, or similar anti-gall stainless alloys (Carpenter Gall-Tough) might be a better choice for the cylinder than 304. Both alloy types typically use Si additions to create more gall- and wear-resistant alloys. You should be able to Google on some of the above terms and get a plethora, if not a veritable cornucopia of engineering data.
RE: Galling threads
It has been my experience that your stated MOC has created some terrible galling problems for me to the extent that the components had to be machined apart.
Here is The HP Alloy site one of many sources of information available for N60.
If you download the 40 page brochure there is some very good information of galling of metals.
http://w
RE: Galling threads
RE: Galling threads
Another consideration is to make the endcap of a non stainless steel. It will get bashed up by rocks in the sediment long before it rusts out.
Back to the galling question: will 304 gall with something like 4130?
cheers,
RE: Galling threads
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http://w
RE: Galling threads
I wouldn't give up on the Nitronics, keep checking around for the availability.
Yes you can add a Nitronic section to 316 SS stock by welding. Just keep the weld joint at least 3 times the length of the threads away from the last thread to retain the antiglling properties of the Nitronic.
RE: Galling threads
This will work harden the thread surfaces and make them much more resistant to galling during use. If you do experience galling, you can repair them and repeat, which would be much better than having it happen during use.
rp
RE: Galling threads
RE: Galling threads
If you roll thread them this will also help minimize galling.
Use a good anti-seize compound designed for stainless.
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Plymouth Tube
RE: Galling threads
http://www.kolsterising.bodycote.com/
RE: Galling threads
Critically important, though, is thread form. The threads MUST be designed and manufactured such that there is NO thread crest-to-root interference. This means proper truncation of the thread crest to clear the root. If you have crest-to-root interference, you will have severed galling no matter what other mitigation steps you take.
Kolsterizing will help very little.
RE: Galling threads