Minimum Shell Course for Pressure Vessel 4

[azmirosman]

Dear All,

I would like to seek your help regarding the minimum shell course width of pressure vessel (horizontal).

My pressure vessel fabricator has prepared drawing according to ASME Sec VIII Div.1 for 7400mm length of pressure vessel which are having 4 shell courses with 4 different length which are 2430mm,2340mm,1630mm and 1000mm.

I would like to know if there is any restriction by ASME on the minimum shell course length.

For this case,minimum course length provided is 1000mm.

Appreciate if anybody can advise.

Thank you

 

[r6155]

No restrictions in ASME.
Regards

 

[MooreHolmes]

A general piece of advice is to have the minimum number of strakes as it results in less welding and less possibility for defects and less testing.
However this will be governed by the capability of the fabricator and not always practicable.
4 seams (no pun intended) quite a lot for a 7.4m length vessel.

 

[saplanti]

And, nozzle and support saddle distribution should also be considered for the strake lengths. None likes weld intersecting nozzles and reinforcement pads. Supporting saddles should be kept out of circumferential and horizontal welds.

 

[MJCronin]

Carefully review the drawings that you will receive from the fabricator showing all weld seams and the location of all nozzles, lift lugs, legs, feet and saddles !!!

Is there any conflict ? ... Are you reviewing these vendor supplied contract drawings carefully ?

Yes, yes I am aware that drawing development and ASME compliance is the vendor responsibility, however

You should carefully review all vendor drawings in light of the recent wave of STEM incompetence in the past few years..

My opinion only ...

MJCronin
Sr. Process Engineer

 

[Christine74]

4 shell courses is basically what you would expect for a vessel that's slightly over 24 ft long because plate material is typically limited to 96 inches wide (at least it is in the US). Sometimes 120 inch or wider plate can be sourced but it's more difficult to transport and to form.

Worth paying attention to up front, for example a vessel that's specified as being 104 inches long from tangent to tangent and has semi-ellipsoidal heads might be substantially more expensive than a similar vessel that's 100 inches from tangent to tangent because you would need 2 shell courses and 3 circumferential weld seams rather than 1 course and 2 circumferential seams (ellipsoidal heads typically have 2 inch long straight flanges).

There are no restrictions on the minimum cylinder length in ASME Section VIII.


-Christine

 

[azmirosman]

Thank you all for the reply and information shared.

Really appreciate it

 

[agit]

To my knowledge ASME Sec 8 doesn't regulate "dimension of course", but it will became cutting plan issue, waste material equal to additional manufacture cost