Vessel Opening 1

[Aconnell]

Hello,

I am looking at laying out a vessel prior to sending it out for budget pricing. For our layout we are potentially looking at having two 20" opening in a 2:1 semi head for an agitator mount and a manhole entrance. To prevent interference of the nozzles the manhole opening would have to pass through the knuckle region of the head. UG-37 gives instruction for reinforcement of openings within 80% of the head diameter, and from what I can see there is no guidance for openings encroaching outside of this area. This leads me to the conclusion that having an opening encroach on the knuckle region is bad design practice. Is this the case and does the PRV code provide direction for this. Any insights would be greatly appreciated.

Thanks in Advance

Alex

 

[TGS4]

I take it that you are using ASME Section VIII, Division 1 for your vessel - is that correct? See the rule in U-2(g). Not that it's necessarily bad practice, only that there are no rules given.

 

[Aconnell]

Thanks TGS4,

Yes I am using Section VIII, Div 1. Thanks for answering my question.

Regards,

 

[jamesl]

It is a bad practice, but it is not prohibited by ASME code, and UG-37 is still applicable. You just misread the code paragraph regarding 80% diameter. If the nozzle is outside of 80% limit, tr should be calculated by code rule for 2:1 head thickness, not seamless sphere.

See code interpretation VIII-1-98-117.