Nozzle loads consideration in Vessel Support / Bracket Design

[DK44]

Dears.
1. In the Design of Horizontal / Vertical Vessels and Heat Exchangers is it required to consider Nozzles loads for the design of supports / Brackets. This will tend to increase Vessel Thickness / Anchor Bolt Diameter / Foundation loads etc.

2. For Heat Exchangers, TEMA-10 Has certain guidelines at RGP-G 7.12. Are these mandatory?

3. PV Elite has an optional input for such forces and moments if one wishes. It gives a message non mandatorily.

4. What are the ASME Sec VIII Div 1 requirements in this instance. Does UG22 loadings imply this requirement?

5. At the proposal stage generally above requirements are overlooked which cause surprises after order.

 

[r6155]

1) YES
2) TEMA is clear: read again
3) I don't use PV Elite. I use my own computer program.
4) ASME is clear: read again
5) The proposal must be clear.

Regards

 

[DK44]

Thank you r6155 for your remarks.
Kindly advise:

2) TEMA at RGP-G 7.1.2 for Vertical vessels, indicates consideration of Applied Moments at the supports due to external loads. Is this RGP mandatory in all cases?

4) ASME Sec VIII Div 1, UG-22 includes super imposed piping loadings but do not appear to require Vessel Supports ( Horizontal / Vertical) to be checked for super imposed piping loads.
4.1 At APP-G4, it does not include to check the superimposed loads for Vertical Leg/Lug supports on Shell.
4.2 However, at App-G5, for skirt supported Vertical vessel, Check of super imposed loads is indicated.
4.3 Is it construed that this check is also requited for G-4?

 

[r6155]

@ DK44
As an engineer, you will need to use your best judgment.
I suggest you read some Pressure Vessels Handbooks (Bednard, D. Moss, .......

Regards

 

[mechengineer]

@DK44,
1. The nozzle loads should not be taken into account for the design of the vessel support . It is the internal forces and moments that is a equilibrium internal force system as long as the structure/component(nozzle/piping) is not failed or break. The external forces to design the supports are only the vessel weight and wind/seismic loads. In additional, those nozzles may help to support the vessel. To simplidy the support design, normally those additional supports would not be considered, that is conservative.
2. Those applicable loads mentioned in pressure vessel codes shall be applied to pressure parts only. For example, the loacal stresses analysis at the pressure part in connections of nozzle to shell or support to shell/head where th external loads applied. Theose stresses are derived from the internal pressure, internal forces and moments.
To understand the above may need a knowledge of mechanical statics.
Regards,

 

[KevinNZ]

@mechengineer

I disagree. The net effect of the loads from attached piping on nozzles must be applied to the design of the vessel supports. Vessel are often the anchor point for the piping. Piping loads (EQ wind thermal) pass through the vessel supports to the foundations.

 

[r6155]

I agree 100% with KevinNZ

Regards

 

[mechengineer]

@KevinNZ,
Nozzle loading as the internal force and moment defined in statics is not possible to make the vessel movement at all except buckling failed of the shell or deforming of piping line due to overloading. Thus the design shall ensure the nozzle load within the allowable range by control the stress and strain at the nozzle and shell within the allowable reange by code. That is all for the nozzle loads consideration.
If the nozzle (as supports) is very strong, that will not require the vessel support. For example, the reboiler attached to column.
Again, the considerable loads of the EXTERNAL force and momnet on the skirt support/saddle support is only wind/seimic/weight. The interal force and momnet would not become the external force and moment in statics analysis.
Regards,

 

[r6155]

@ DK44

See PD 5500:2018 Section 3

3.7 Supports, attachments and internal structures
3.7.1 General
Supports, attachments and internal structures shall be designed to withstand all
loadings likely to be imposed in service due to pressure, weight of vessel and
contents, machinery and piping loads, wind, earthquake, etc.

Regards

 

[r6155]

More
PIP VESV1002
Design and Fabrication Specification for Vessels - January 2019

8. Piping and Superimposed Equipment Loads [pre](L8)[/pre]
Loads caused by piping (other than the Dead Load), and loads
caused by superimposed equipment

4.2.3.2 Load Conditions
Unless other conditions are specified by the Purchaser, vessels and their
supports shall be designed to satisfy the most severe (i.e., controlling) of
the following load conditions, and the controlling load condition shall be
identified in the design calculations:
a. L1+L6
Operating Dead Load with full Wind Load

b. L1+L2+L3+L4+L6+[pre]L8[/pre]

Design Condition with full Wind Load. Both full and zero pressure
loads (L3) shall be included for check of maximum longitudinal
tensile and compressive stress.

c. L1+L2+L3+L4+L7+[pre]L8[/pre]
Design Condition with Seismic Load. Both full and zero pressure
loads (L3) shall be included for check of maximum longitudinal
tensile and compressive stress.

Regards

 

[DriveMeNuts]

There seems to be a lot of theoretical bureaucratic ideological answers above.
If the nozzle is small and flexible then use your judgement and ignore the effect of the loading on the supports (ASME does allow the use of judgement.)
If the nozzle is large then its effects on supports need to be considered. It is a requirement of good engineering practice. There is no need for there to be an ASME clause for this, even of there is one.

From the OP, it looks like the loads from the nozzle in question does cause large loads and stress, requiring that the supports and shell need to be beefed up.
I don't understand why the question is being asked. It is like the OP is asking if someone knows how to defy the laws of nature, or, "Do we really need to follow good engineering practice?"

 

[Trestala]

You have to understand what the nozzle load values represent before superimposing it to the support. Part of these loads will not be transferred to the support while the other part, such as dead weight, will be transferred to the support. The other component of these nozzle loads such as those due to pressure thrust or thermal expansion, those may or may not be transferred to the support depending on how the attached piping is supported. There is a lot of discussion regarding this topic.