weld joint catagory.

[RAJU KUMAR]

 elipsoidal/torispherical dish to shell joint come under "A" catagory while the same joint with hemispherical dish to shell come under "B" catagory. Why????????

[raj vikhar]

Dear Mr Raju - Good quetion

First of all If I understand correctly Catagory A refres to Hemisperical and B for other Dish end

 

The only reason I could understand is criticality of service . As Hemisperiacal Dish are use when there is high pressure. Hence this joint also consider as critical joint .

 

Trust this calrifies.

 

( As per EN 13445- Page no 24 this covers under catagory 5 Joints )

 

Regards

Vikhar Rajesh

Lead Mechanical

Aibel Singapoore

www.aibel.com

 

On Sun, Mar 10, 2013 at 6:11 PM, RAJU KUMAR <raju149...@gmail.com> wrote:

 elipsoidal/torispherical dish to shell joint come under "A" catagory while the same joint with hemispherical dish to shell come under "B" catagory. Why????????

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[royster cabral]

Raju.

The reason for using Hemispherical head is that in comparison to ellipsoidal head it required a considerably lower thickness.
Due to this there a major thickness difference between the shell and hemispherical head thickness and we have to provide a joint as per detail FIG. UW-9 (ASME Div-1).
As per this joint design we consider a portion of the hemispherical head to be located in the shell , hence the tan line being located on the shell for hemispherical heads.

Since this portion that is located in the shell is effectively a part of the hemispherical head and all joints in heads are category "A".
Hence Hemispherical-Shell C.S joint are category "A".
Hope this helps

Regards
Royster Cabral
Mechanical Design Engineer.
Dubai.

[raj vikhar]

NB!

Shell Cirseams joints are category B

--

[royster cabral]

Rajesh,

For hemispherical dish ends, the shell-dish end joint are considered as a part of the head itself and hence the head-shell joint being "A".

On Sunday, 10 March 2013 14:11:21 UTC+4, RAJU KUMAR wrote:

[Rajesh]

Reason is simple. Ellipsoidal & torisperical head as Straight face while Spherical don't have.

[Rajesh]

Agreed