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3.5% Ni

3.5% Ni


Mounded Bullet
DP = 17.5 barg
DT = -46 / 80 deg C

Based on the above design conditions I have selected MOC for Shell/Dish plate SA 350 LF3 and same is procured by vendor. Now client is not accepting this material because of Ni content of 3.5% as it is specified in the client specification that 3.5% Ni shall not be used and asking me to go with SA 350 LF2 cl.1.

Since the material has already been procured, client is asking me to give proper justification to take deviation to specification for using SA 350 LF3 instead of SA 350 F2 Cl.1 material.

Please let me know if any other information is required

kindly help me to solve this issue.


RE: 3.5% Ni

You may have had some responses to this by now if this was posted under materials engineering. I'd be interested in the feedback you get also. Maybe delete this and repost in materials engineering.

RE: 3.5% Ni

We have also a processfluid that reacts with the nickel.
We absolutely don't want Ni in the fluid.

RE: 3.5% Ni

DP = 17.5 barg
DT = -46 / 80 deg C
Hi Arvind,

For the above design condition 3.5% Nickel Steel is grossly over designed. 350 LF2,cL-1 materials with guaranteed impact @-46 Deg C would meet your design requirements. If the process fluid is LPG or other compressed gases you should not have concerns with respect to impact with SA 350 LF2 cl.1 steel down upto -46 deg C.

If you choose 3.55 Nickel steel for D.E then all welding on this material has to be done with matching 3.5% steel welding consumable, which involves extra money. If the design conditions are such that it could go well below -46 Deg C, say -60 Deg C or still below then I've seen designers opting for 2.5% Nickel steel.But choosing 3.5%nickel steel is grossly overspending.

You certainly don't want your client to pay the bronze and you deliver him something made of gold.


Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
All provided answer are personal opinions or personal judgements only. It's not connected with any employers by any means.

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