WELDED STAYS ON FIRED-PRESSURE VESSELS 1

[ichini686]

Hi,

I am currently working on fired-pressure vessels. We are currently having trouble in welding stays in the tube sheet of the vessel specially during welding. The main problem that we are having are the lack of penetration of the welding. Some of our associates suggested that we can do a partial penetration on the the stays as illustrated in ASME 2011a Sec. VIII Div. 2 - Alternative rules Part 4.9.4, Fig. 4.9.1 (d). But there is a note at the bottom indicating that the "ts is the nominal thickness of the thinner stayed plate."

Does this mean that if I have a uniform thickness tube-sheet, despite having computed for the allowable shear stress of the material and welding to get the thickness of the welding, the welding thickness required for the stays will still be equal to the thickness of the tube sheet?

 

[chicopee]

Have you checked the ASME/NB Power Boiler Code I for details? I am assuming that you are refering to diagonal stays.

 

[ichini686]

Hi Chicopee,

Yes, I'm referring to the diagonal stays attached at the tube sheet and shell of the pressure vessel. I've already checked Section I of the code and it does not show/tell any alternatives with regards to the attachment of the stays. It only tells about the typical attachment of the stays on the tube sheet that's why I've resorted into searching in the other sections of the code.

Is there any other alternatives aside from this?

Thanks so much in advance.

 

[chicopee]

I would follow the Code, however, research older codes when revited construction was prevalent.

 

[GenB]

lock of penetration is your welder not doing it right, get another welder or train your welder or find/try a different procedure.
you will not find a different edition of sect VIII or I to allow partial. there is a bolted procedure...