Multiple Heat Treatment 2

[RiyadhBPV]

Dear all,
A pressure vessel to be designed acc. to the following conditions:
- Design Pressure: 600 psig
- Max Design Temperature: 240 F
- Min Design Temperature: 32 F
- Internal Diameter: 144 in
- Corrosion Allowance: 0.125 in
- Material: SA 516 Gr. 70
- Design Code: ASME BPV, SEC. VIII DIV 1
I select 2.375 in thickness for the elliptical head (After Forming) to satisfy internal pressure design.
Now:
- To satisfy MDT the material shall be Normalized.
- As per UCS-56, Table UCS-56-1 & since the welded joints over 1 1/2 in nominal thickness, PWHT is MANDATORY.
- As per UG-79, The calculated extreme fiber elongation percent exceeds 5%
- As per UCS-79 and since extreme fiber elongation percent exceeds 5%, the head shall be Post Forming Heat Treated (PFHT)
My question is:
Is it practical to apply 3 stages of heat treatment (Normalizing, PFHT and PWHT) for my pressure part?
Thank you all from heart

 

[david339933]

You can, or just do two...normalizing and PWHT. PWHT is the same as PFHT.

 

[david339933]

Standard Designation:

BPV Section VIII Div 1

Edition/Addenda:

Para./Fig./Table No:

Subject Description:

Section VIII-1, UCS-79(d)

Date Issued:

03/04/1983

Record Number:

BC82-798

Interpretation Number :

VIII-1-83-105

Question(s) and Reply(ies):

Question: Does heat treatment per UCS-56 satisfy the requirements of UCS-79(d) of Section VIII, Division 1, when the extreme fiber elongation is considerably more than 5% and any of conditions (1) through (5) exist?

Reply: Yes.

 

[david339933]

Standard Designation:

BPV Section VIII Div 1

Edition/Addenda:

Para./Fig./Table No:

Subject Description:

Section VIII, Division 1 (1992 Edition, 1993 Addenda); UCS-79(d)

Date Issued:

03/13/1995

Record Number:

BC94-684

Interpretation Number :

VIII-1-95-50

Question(s) and Reply(ies):

Question (1): A cold formed head has to be heat treated to fulfill the requirements of UCS-79(d) in Section VIII, Division 1. Does the term "heat treated subsequently" mean just after forming and prior to any other operation?

Reply (1): No.

Question (2): If Reply (1) is no, then will PWHT in accordance with UCS-56 satisfy the requirements of UCS-79(d) following welding of the head to the vessel?

Reply (2): Yes.