Horizontal shell with a tangent manway

[eng741]

Hello all,

I am trying to find documentation/limitations about a manway being tangent to a horizontal shell.
I found some documentation and formulas for the manway and how far it can be from the center of the elliptical head but nothing about being tangent to the shell.

Thanks in advance

 

[TGS4]

I know of no reasons that such an arrangement would not be acceptable. Evaluating the stresses at the opening may be challenging. Assuming VIII-1 construction (BTW, it would be very helpful for you to mention the Code of Construction in your original post), you may be able to use UG-37 with some conservative assumptions. Otherwise - U-2(g).

 

[nickelkid]

The documentation/limitations should be the same as a nozzle. I imagine you have some good reasons for this, but I am at a loss for tangential manway specific documentation.

 

[eng741]

Thank you for the quick reply

The tangential nozzle is just for maintenance purposes. They are wanting to attach the manway tangent to the shell for ease of cleaning.

Would there not be limitations on how far the nozzle can be parallel/tangent to the shell since they would have to cut the edge of the head. The vessel is in service with 40 psi internal and 10 psi external pressure.

Thank you,

 

[nickelkid]

If you are cutting through the shell/head seam I would avoid that

 

[TGS4]

There are no specific limitations. However, if there are not rules available in (again, assuming) VIII-1, then you would U-2(g).

 

[eng741]

Thanks again

I will look more into it

 

[SnTMan]

eng741, tangent nozzles are not all that uncommon. As TGS4 has stated UG-37 rules may be used. A practical difficulty is presented by the limits of reinforcement in the main shell. A way around this without going thru an advanced U-2(g) analysis is to consider there is no excess thickness in the shell therefore it does not contribute to reinforcement. Most software permits this. Of course then all reinforcement is provided by the nozzle.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[chicopee]

Now, I am confused; are we talking about manways(or commonly known as manholes) or about nozzles?

 

[jte]

Now, I am confused; are we talking about manways(or commonly known as manholes) or about nozzles?

Well, a manway (aka manhole, accessway, etc.) is physically and design wise about the same as a process nozzle, isn't it? With the exception of imposed piping loads and the UG-45 minimum thicknesses being a tad thinner in a small number of cases, the only difference between a 24" tangential process nozzle (e.g. feed inlet on a rather small refinery vacuum distillation column or a cyclonic separator) and a 24" tangential manway is the blind flange and manway davit or hinge. Of course, in the case of the manway, the Section VIII Div. 1 scope is extended a bit to include the blind, whereas with a process connection the scope is typically limited to the face of the vessel flange.

What, specifically, do you find confusing?

 

[chicopee]

jte, I could call a mule a horse but it ain't. Also the ASME code design procedure for manholes or manways is different than the procedure for nozzles.

 

[SnTMan]

Regarding UG-37 reinforcement calculations, no difference between the two.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[SnTMan]

Its just an opening in a vessel.

The problem with sloppy work is that the supply FAR EXCEEDS the demand