Dear all,

Vessel thickness is 6.35mm.
Reinforcement pad thickness is 8mm.
My weld size shall be 4mm.

Is it possible to weld 8mm reinforcement pad on vessel?.

Hello Shabeer

It depends on the pressure vessel code. The European codes do not like pads that are thicker than the shell, to which they are attached or exceed 40 mm thickness. However, if the code is ASME Section VIII, Division 1, the code does not say how thick the pad has to be. The weld size is determined from formulae in the code. I suggest you refer to section UW-16 and Figure UW-16.1 of the code for weld details.

It is not recommended as you are creating a stiff spot (with high stress concentration) on the vessel, you have to worry about the fatigue failure.

In my opinion, avoid using a pad thicker than the shell.

Shabeer,

It is good practice to use pad of same thickness that of shell/dished end on which it is attached. ASME has not specified maximum pad thickness but it shall be withing reinforcement limit in that direction.

Yes you can use 8 mm thick pad on 6.35 mm shell thickness. Some books has shown maximum limit up to 1.5 times the shell/dish thickness for good engineering.

Mukesh Chopra
www.theculminates.com
M: +91-9428500192

There is one sobering thought on the use of pads. Formerly in the nuclear code, pads were not allowed. Nozzles had to be self reinforcing. This was for precisely the reason outlined by Mandeep - they were a fatigue hazard. Anywhere you have an abrupt change of section; fatigue is waiting in the wings.

HELLO SHABBIR,

i m not able to understand frm where r u getting 6.35 mm thk of plate.It is what obvious 7 mm is also not available in markket so will procure 8 mm thk plate for shell.

Now the question is can i weld 8mm thk plate on 6. 35 mm palte thortically.. then i will say yes. Because ASME code do not prohibit to use more thk of pad rather than shell.

Now just leave the code now think about engineering point of view & i agree with MR. RAY VIEWS also.

One more ting if your nozzle is pass under reinforcement condition but failing under local loads then will u increase the thickness of local shell or RF PAD . sometimes economy of job also matter.

REGARDS
MUKESH KALRA

7 mm thick available.

In some countries plate are procured with thicknesses in inch not in mm.So 6.35 is possible.

8mm pad is ok as fillet size is less (4mm).

I THINK,

only shabbir can tell what the thickness he is getting 6.35 , 7 or 8.

as i assume shabbir is an indian & he will get 8mm only. SOMETIMES PRACTICAL APPROACH ONLY WORK OUT.

SO SHABIR NOW U PLEASE TELL US WHAT THICKNESS YOU R GETTING.

Mr. Kalra,

Yes. you are correct, I am an indian. But we are doing foreign projects only. 1/4" thickness plate is available in foreign market.

THEN GOOD , GO AHEAD WITH 8 MM THK PAD

ASME DOES NOT RESTRICT YOU. But most of client specification does allow to
use higher thickness of pad w.r.t to shell or dish.

shabbir,
you can also get 7 mm in some countires.

Hi Kalra/ise12345,

Thanks for your response