If a Vessel fabricator proposed a different Plate material to be used for Nozzle Neck ( large sizes ) would it be acceptable?

Instead of using plate similar to shell/head, Pipe or Forging .
Vessel is Code Stamp.

Thanks,
Gilbert

If nozzle neck is rolled from a plate, it is generally the same material as of Shell/ Head MOC. This is logical also since you probably have this plate/ MOC in your stock.

You can use an alternative material also if metallurgy is suitable for the required operating condition and you have established a welding procedure to weld this alternative material with shell/ dieshed end/ flange.

Regards

Sanjeev

What kind of Diff. materials are there?

_________________
Niraj

Hi Niraj,
SA-537 CL2 SHELL/HEADS, SA-516 70N FOR LARGE NOZZLES
Thanks,
Gilbert

Just from First view i think :

1- Chemical Anlysis : Critical point is Cu,Ni,Cr,Mo % contents for 516-70 sholud match SA537 Cl-2 .

2-Physical Analysis:- Critical point is MIN.Yield is 60 ksi for SA537 and for 516 it is 38 ksi -and accordingly Elongation %.

3- Manufacturing of SA-516-70 plate conditions :like Heat treated,Carbon Eq.,Killed condition, etc.

4- Others- Like NACE req..HIC req.,Amine req. Impact req. etc.

As such this is code stamp your AI will guide you better But if all above points are meting with sa-537 Cl 2 req. there won't be big issue.

_________________
Niraj

And above all

You have stated Large size is this Large opening ?
then calculation should match for Bending & Membrane stress combined load you have to calculate and shall be lower then allowable stress for 516-70 at particular temp.

_________________
Niraj

Another question is, when is the material changed?

If during the design phase, it will be adressed in drawing and calculation,no problem.
If the material is changed later, the manufactuer must inform his inspector and obtain concurrence of the AI.

The AI will request evidence that the material has the same stress properties and thermal expansion,and impact properties.

DK

Gilbert,

As such there seems to be no problem is using SA 537 Cl 2 in place of SA 516 Gr 70 or SA 106 Gr B. I am trying to clarify some of the questions raised in subsequest discussion. Any one please correct me if I am wrong;

1. Probably Gilbert does not mean large opening for design purpose. Large nozzle probably meant that nozzle neck is rolled from plate instead of using a tubular material.

2. Both the material (SA 516 and SA 537) are CS material. SA 537 is Heat Treated C-Mn-Si steel and therefore do not think that there is any problem from metallurgy/ corrosion point of view for replacing SA 516 with SA 537.

3. Carbon content of SA 537 is less that SA 516 Gr 70 and both are killed fine grain steel.

4. SA 537 is on curve D of UCS 66 where as SA 516 is on curve D only if it is normalized and therefore Impact properties should not be a problem.

5. For nozzle neck, use of SA 106 Gr B is very common which has got tensile properties (UTS & yield) less than SA 516 Gr 70 and therefore requirement of same allowable stress is not a problem. SA 537 however has got higher tensile properties as compare to SA 516 Gr 70.

6. SA 537 Cl II is high strength (UTS & YS) and therefore may not be suitable in case HIC/ SSC etc is a requirement.

7. Elongation ckeck is not a requirement for SA 537 Cl II

For a simple/ non critical application replacing SA 516 Gr 70 with SA 537 Cl II seems to be not a problem however in case of critical services such as sour application where HIC/ SSC or some special testings are required or stress critical services such as fatigue etc where ductilicity/ elongation is critical, probably you need to consult your metallurgist and AI.

Regards

i think sanjeeve gilbert wants to replace 537 and wants to use 516-70

that's what i understood
Better gilbert has to reply on this

_________________
Niraj