Bolting 316L to inconel 625 ?
Bolting 316L to inconel 625 ?
(OP)
Just want to pick the collective brains.
We are currently in design phase for some internals to be installed into a Inconel 625 weld overlayed vessel (gas scrubber service). Our intenals are typically 316l, bolted with A4 grade 316 bolting.
Are we ok to use the A4 bolting direct to the Inconel lugs on the vessel from a corrosion point of view?
Many thanks,
Scott
We are currently in design phase for some internals to be installed into a Inconel 625 weld overlayed vessel (gas scrubber service). Our intenals are typically 316l, bolted with A4 grade 316 bolting.
Are we ok to use the A4 bolting direct to the Inconel lugs on the vessel from a corrosion point of view?
Many thanks,
Scott





RE: Bolting 316L to inconel 625 ?
hope this help
S.
http://www.corrosionist.com
RE: Bolting 316L to inconel 625 ?
That is what I was hoping to hear.
The vessel will be seeing very little fluid and by this point of the process train it really should be oil as opposed to water.
many thanks.
Scott.
RE: Bolting 316L to inconel 625 ?
If your system stays dry then you should be fine, but any moisture in these connections and the 316 bolts could fail fast.
Would it kill you to use 625 hardware?
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RE: Bolting 316L to inconel 625 ?
Its not really my call.
We sold based on 316 and therefore all I can do is make the technical case for a change and see if the project will suffer the subsequent financial impact.
Our kit most definitely shall not be changed to Inconel 625 (too much to ask cost wise) so I would hasten to guess that the risk would simply move further up the chain from bolting/lug to bolting/internal.
Scott.
RE: Bolting 316L to inconel 625 ?
From work I had done a decade ago (seawater immersion, mind you), I found the "closeness of two materials" on a galvanic series to be very misleading to many, especially when two passivating materials are involved (it didn't take much for one material to depassivate locally).
I recommend seeking a more noble fastener, maybe titanium, but I think the cost may force you to say with the CCRES.
RE: Bolting 316L to inconel 625 ?
As stated above you shouldn't have any trouble with 625 with 316 fasteners. We used a similar combination, 600 and 316 for many years without any problems in a extremely corrosive service. This process required that the equipment be steam cleaned about every 72 hrs, so the fasteners would see a different corrosive environment for about 8 hours. There was never any corrosion noted in the system over many years operation.
We use both 304SS and 316SS fasteners by the ton in contact
with our process.
RE: Bolting 316L to inconel 625 ?
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdo/
RE: Bolting 316L to inconel 625 ?
Steve
The Client specified the material for the vessel and the internals.
The internals are designed to be removable and therefore replacable.
There life span is considered to be less than that of a vessel regardless of material, as they will most probably be optimised during the lifetime of the well to accomodate changes in production.
For this reason clients tend to opt for them to be made from a less resistant material than they would accept for the vessel.
Thanks Scott.
RE: Bolting 316L to inconel 625 ?
I've seen it in many of our vessel in oil & gas production.
S.
http://www.corrosionist.com
RE: Bolting 316L to inconel 625 ?
I have no experience with it myself.