ASME Section VIII, UG-36 etal provisions for openings in Pressure Vessels seem confusing. Is it possible to have an opening diameter as large as the pressure vessel diameter? For instance, if one were to have a cylindrical pressure vessel having a diameter of 18", can you weld a nozzle having a diameter of 18" perpendicular to the vessel and conform to the Code? I say that you can not. There would be no room for providing cover fillet welds and or reinforcing pads which would probably be required under the code formulas and Appendix 1-7.
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Max Size of Openings in Pressure Vessels 1
- Thread starter spike
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The APIGUY....I don't find ASME VIII confusing about size of openings: UG-36 to Ug-43 apply with some limitations (UG-36(b)) and 1-7 requires for much care when higher sizes are required.
In your limit condition I think that proof testing (e.g. strain gauges) would be required to satisfy code rules. prex
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In your limit condition I think that proof testing (e.g. strain gauges) would be required to satisfy code rules. prex
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Outside nozzle’s diameter shall not exceed inside shell’s diameter.
The solution ‘apiguy’ suggests is correct to my opinion. I suppose you are using 18” pipe for vessel’s shell. You may place a standard 18” Tee as a part of the shell (UCS-27: Shells Made from Pipe).
The solution ‘apiguy’ suggests is correct to my opinion. I suppose you are using 18” pipe for vessel’s shell. You may place a standard 18” Tee as a part of the shell (UCS-27: Shells Made from Pipe).
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Per 1-7(c), "appropriate proof testing may be advisable in extreme cases of large openings approaching full vessel diameter, openings of unusual shape, etc."
Per U-2(g, the Code acknowledges that it does not contain rules to cover all details of design & construction. Where details & design are not given, the Manufacturer, with acceptance of the inspector, may provide design details which will be as safe as those provided by the rules of the Code.
Design methods from other Codes or accepted engineering practice may be used where Section VII does not provide rules, with necessary adjustments to the factors of safety.
AWWA M11 provides rules for very large opening, approaching & equal to the shell diameter.
B31.1 & other B31 piping codes provide rules for large openings. Use of a tee is an option, using B31.1 rules.
Per U-2(g, the Code acknowledges that it does not contain rules to cover all details of design & construction. Where details & design are not given, the Manufacturer, with acceptance of the inspector, may provide design details which will be as safe as those provided by the rules of the Code.
Design methods from other Codes or accepted engineering practice may be used where Section VII does not provide rules, with necessary adjustments to the factors of safety.
AWWA M11 provides rules for very large opening, approaching & equal to the shell diameter.
B31.1 & other B31 piping codes provide rules for large openings. Use of a tee is an option, using B31.1 rules.
- Thread starter
- #10
Spike thanks everyone for the replies. The use of tee fittings is not possible. The concept is how to weld a nozzle having the same diameter as the vessel and still comply with the Code. A full penetration weld would be used, but additional reinforcement would not be possible because the diameters are the same.
Note that the addition of separate reinforcement plates is not impossible, but useless, as they would have to be formed with the shape of the tee: much simpler to increase the thickness of both shells to provide the required reinforcement. prex
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deanc,
You are correct. The design package must be accepted by the AIA. This includes design methods within the Code, & those offered based upon good engineering practice where the Code does not offer methods or formulas.
Use of methods not contained in the Code must be adjusted to Code allowable stresses
You are correct. The design package must be accepted by the AIA. This includes design methods within the Code, & those offered based upon good engineering practice where the Code does not offer methods or formulas.
Use of methods not contained in the Code must be adjusted to Code allowable stresses
hockchong
Mechanical
- Dec 9, 2002
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Hi Everyone,
Is there any limit specified in PD5500? I have a case here where the OD of nozzle 1110mm and the vessel OD 1170mm. I need a clause stated in the PD5500 code that mention that the size is violating the code as they don't accept my explanation on practical fabrication issue. Thanks and I need this urgently.
Thanks again.
Regards,
Lee
Is there any limit specified in PD5500? I have a case here where the OD of nozzle 1110mm and the vessel OD 1170mm. I need a clause stated in the PD5500 code that mention that the size is violating the code as they don't accept my explanation on practical fabrication issue. Thanks and I need this urgently.
Thanks again.
Regards,
Lee
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