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Question about Dilution of P1, P4, P5A and P7 material - ASME Sec. VIII Div. 1 Vessel

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m4metz

Mechanical
Feb 21, 2017
1
HI all experts,
I have a question about the dilution, procedure qualification, and process impacts on the Vessel
I have Vessel with SA 516 Gr 70 (P1) material, The tangential nozzles on the vessels are of SA 3355 P11 (P4) and SA 335 P22(P5A). Inside the vessel is wear plate on tangential nozzles. Wear plate is of material SA 240, Type 409. The vessel is being PWHT at 690 + or - 10 degree centigrade. The designer has given 5mm gap between wear plate and tangential nozzle welds. But physically When the welding will be performed there are two possibilities in hand,
One possibility is that the desired gap between the welds of P7+P1 and P1 and P4 ... P7+P1 and P1 and P5A will be more than is mentioned in the drawing in that case there will be space between these two welds and some area of P1 material of PV shell will not be covered in the welding, hence will not have any wear resistance.
Second possibility is that the area between P7+P1 and P1 and P4 ... P7+P1 and P1 and P5A which will be left un welded will be covered with the ENiCrFe-3. All of the combination has been qualified with PWHT already i-e. P1 to P7, P4, P5A, P4 and P5A to P7.

My Questions are:
Whether the un-welded area which is covered by deposition of metal ENiCrFe-3 will be covered by the already qualified PQR or it will be considered the Hard surfacing/Surfacing as per ASME Sec. IX.
What will be the effect of Dilution? Is there a possibility of Crack on the said area?
What will be the metallurgy of the weld metal in the said area.
For details please see the attached Picture.
 
 http://files.engineering.com/getfile.aspx?folder=b2f8bfee-e725-46f3-91fa-bf08e7a88510&file=P1,_P4,_P5A_and_P7_Dilution_case_drawing.png
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I am not sure why they left the gap but technically speaking the bare area should be qualified as a corrosion resistant overlay or hard surfacing. Two layers will provide a chemistry near that of the ENiCrFe-3. A single layer will have lower chemistry and that will be determined by welding process and heat input.

 
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