Welding inconel 800 ring to 516gr70 body flange

[Aloni]

Dear expert
I need to design a pressure vessel
Design pressure is 13.5 barg @ 350°c (195 psig@650°f)
My main concern is the body flange connection.
I have 2 option..
one :
is the to do an overlay with alloy 82 to the body flange 115 mm thk (about 5 mm thk overlay)
Second:
is to weld inconel 800 ring ,8 mm thk( kind of a stub end) with alloy 82 the body flange 115 mm thk.

The first option is more complicated due to the distortion on the 115 thk flange and due to the PWHT - that I won't to avoid.

The second option seems to be more practical but I am not sure if I need to perform PWHT also?
regarding the thermal expansion between the two materials, The weld in zone 1 will hold acc to the calculation ( the difference in expansion between the 2 material is 0.056 mm)
Please share your opinions

See the attach file.

Regards
aloni

 

[weldstan]

There is no PWHT requirement for the Alloy 800 to SA-516 70 welds under ASME VIII, Div.1.

 

[Aloni]

Thanks

 

[pvros]

Hi,
I would not accept a proposal per your sketch.
Typically, flange type, gasket, material are all decisions taken by client.

Generally speaking, what is the internal diameter? Is the shell integral in alloy or CS+CRA? Is really not economical provide an integral flange base on flange dimension?

I would choose between the following options and probably decision shall be based on client requirements.
1 - solid flange in alloy if shell is integral in alloy
2 - lap joint flange (sometimes not accepted by clients)
3 - CS flange with WO. Distortion is not an issue as long as you follow the correct fabrication sequence -> flange machining after WO and preferable seating surface machining after welding the flange to the shell.

 

[Aloni]

Hi thaks for your answer.
The skatch is only to illustrate
The conection of the flange to the shell and to the stubend
From the point of view thermal stress in zone1.
Regarding the id of the shell,
It equals to the id of the inconel 800 ring 1114 mm.
The client accept the two option
1. Cs flange with alloy 82 overlay
2. ⁠cs flange with stub end ring alloy 800
The cs flange is not a lap joint
Because of the weld in zone 1&3
But calculate as lap jont.
The propers of the weld in zone 1 is to allow proper machining.

My qwestion is regarding pwht
Deu weld zone 1
Regard
Aloni

 

[pvros]

Check table UCS-56-1

 

[Aloni]

Thaks pvros
Regard
Aloni

 

[r6155]

For 350 °C it must be integral flange, full penetration weld.

Regards

 

[CuMo]

Just do a LAP Joint flange design if allowed. Then no PWHT would be required. (Do not weld the Inconel to the C/ST whatsoever).

You can weld the lap to neck followed by a face skim, something like this:

https://ibb.co/WDx8Sts

By the way, if your design code is PD5500 -> the lap must be checked separately as a flange on its own for shear and bending stresses. ASME VIII-1 is more friendly in this case.