Nickel content limit from NACE0175? 6

[salmon2]

Experts, wondering why NACE0175 has a nickel limit as 1.0% on carbon or low alloy carbon steel?

For example, 4340 and 4330V are are excellent through hardening material for large diameter stuff. But they are out given the 1.0% limit on Nickel.

Thanks a lot for your any inputs in advance.

 

[redpicker]

For resistance to sulfide stress cracking (SCC)

rp

 

[salmon2]

Thank you so much, redpicker. But can you elaborate the reason a little more. Or anything you can direct me to read?

 

[blacksmith37]

I suspect Ni /Mn rich volumns retain austenite; later it forms "fresh" martensite which is prone to SCC / HSCC.
Dr Bruce Craig (Oilfield Metallurgy and Corrosion) did a lot of consulting/ publishing for Inco and NiDI (?) to get higher Ni accepted but was unsucessful. Craig has other pubs including SPE -Sour Gas Monograph.
BP had a very $$$$ riser failure (before start-up) of platform (not- Crazy Horse, cuz the indians didn't like that name) ,caused by HSCC of big (like 5") 4340 studs in riser flanges. This failure cause has not officially been resolved as far as I know.
Redpickers answer is correct but not as much fun.

 

[mcguire]

I wouldn't look for a whole lot of science on this one. Someone probably had a problem and blamed it on nickel. I have searched the entire literature on this topic and nickel is not a contributor in any way. On the other hand, it doesn't do any good, either. It's about as neutral to the issue as anything can be.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[SJones]

Seconding that. MR0175 was constructed upon empirical observation and oilfield legend with conservatism thrown on top. But now that it's ISO 15156, things are a little more scientific. There is a direct statement that more than 1 mass% nickel in deposited weld metal is acceptable if it has been successfully SSC tested. Indirectly, there can be more than 1 mass% nickel in parent material if it too has been tested. The 1 mass% limit is just a threshold for no testing - testing.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[blacksmith37]

I would say ISO is much more political than NACE / API ; Their first attempt at writing a replacement for API 5L was political BS. It took some effort to get MR01-75 adopted by ISO with out added garbage.
Inco /Dr Craig , and many others never could show that Ni (and Mn) were not a problem for HSCC ;Although there may not be a neat explanation ( literature by Treseader, Kohut, etc at Shell would be a place to start looking for history). Experienced organizations that want to minimze risk of HSCC limit Ni/Mn: So specs for high strength steels where there is a risk of HSCC limit Ni and Mn (austenitizers) ,eg. API C90, T95, C100 /110 (not official) , ASTM A387, A542, etc .(I do admit to being obsolete so there are likely newer ASTM specs.).

 

[valvesarefun]

I posed a similar question at a MR0175 class i just took at the begining of June @ NACE here in Houston. The answer given was(paraphrased of course):

MR0-175 was written using a number of different scientific and quasi-scientific sources. I wouldnt read too far into the nickel requirements other than to say that it was the observation of the researchers, and available field data, that steels with less than 1% nickel did not crack, and those with higher nickel were more prone to cracking.

As mentioned by (SJones) MR0175 does allow for you to qualify the material by a couple of different methods. Others have mentioned that Nickel content might not be that detrimental, so it might be worthwhile for you to qualify your part.

I am curious though, if you temper the 4330 back to the 22HRC requirements wouldnt that lower many of its mechanical properties that might have made it an attractive alloy in the first place?

-vrf

 

[mcguire]

The science is that alloying with nickel in martensitic steels limits the temperature at which one can temper the martensite, because it promotes re-formation of austenite at lower temperatures. Tempering reduces the dislocation density if done at a sufficiently high temperature. It also coarsens carbides. This lowers yield and tensile strength and dramatically reduces (x10)dislocation density, vastly lowering hydrogen trapping capacity.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[redpicker]

Redpickers answer is correct but not as much fun.

It's not supposed to be fun. If it was fun, they woulnd't have to pay me.

Seriously, though, blacksmith37 pretty much hit it on the head. When I first heard about the limit, over 30 years ago, I thought it had to be a mistaken cause and effect correlation. Back then, everyone was using "22 HRC max" and "< 1% Nickel" and even 80,000 psi yield material was really pushing it for sour service applications. I've developed chemistries that can now be pushed from 110,000 to nearly 120,000 PSI yeild and up to 32 HRC that will survive a Method A test at 85% SMYS for 30 days. Since that is rather common these days, they have started wanting Method D to give something like 28 KSI in^.5 or so. As soon as you crack the nut, they move the goalposts.

Anyway, you won't find anyone making any of these high strength sour service steels that doesn't limit the Nickel to 0.15% or less. It is a real effect, so don't write it off as some old-timer's blaming a failure on nickel and nobody questioning it.

rp

 

[SJones]

BP had a very $$$$ riser failure (before start-up) of platform (not- Crazy Horse, cuz the indians didn't like that name) ,caused by HSCC of big (like 5") 4340 studs in riser flanges. This failure cause has not officially been resolved as far as I know.

Was it not actually manifold welds owing to embrittlement of dissimilar metal buttering discussed in NACE 2009, Paper 09305?

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[blacksmith37]

The BP failure I had in mind (HSCC of 4340 studs) was in the (mid?) riser flange , > 5yr ago.
Agreeing with Red; the first good C 110 ( 4 mills worldwide in ca. 1992) used very high double temper of Cr :Mo conpositions. (And longer radis of the NACE 0.252" test bar). One european mill kept trying to also use Mn (+ Cr:Mo) but couldn't make good T-95 (at that time).

 

[salmon2]

To valvesarefun:

My example of using 4340 wasn't a good example. Few or nobody will try to temper it below 22HRC, even though I think it has its benefits if it is possible, such as deeper hardenability for large diameter bar stock, good low temperature toughness from higher Nickel. I admit I never seen a Q&T 4340 < 22HRC.

To redpicker:

I think your very first post meant stress corrosion cracking, a typo. Your abbrevation got it right.


Everyone, thank you so much for the input and they are indeed excellent discussions. I need time and experience to fully understand some of them though.

 

[redpicker]

To redpicker:

I think your very first post meant stress corrosion cracking, a typo. Your abbrevation got it right.

Actually, I meant Sulfide Stress Cracking, my abbreviation was incorrect, it should say SSC. Sulfied Stress Cracking is a specific sub-set of stress corrosion cracking. The specific tests and methods used to control SSC can very specific to H2S exposure and may not apply to other forms of SCC (chloride, ammonia, etc...)

rp

 

[salmon2]

Sorry playing smart pants and thanks for clarifications

 

[stanweld]

Salmon2,
Actually the 4340 is a very good example. This was tha alloy (vs 4140) which originaly exhibited the susceptibility to SCC. Additional materials testing was done and the results led to 1% max Ni limitation into MR 0175.

There was also considerable published work by others to refute the requirement in the mid to late 1970's.

 

[salmon2]

stanweld, thanks a lot for the info.