API Storage 650 Tanks - Nozzle Loads
API Storage 650 Tanks - Nozzle Loads
(OP)
I would be interested to hear of fellow engineers thoughts and experiences on nozzle load design / application to API 650 Storage Tanks.
I typically try to remove all nozzle loads to tanks as far as possible in agreement with our piping stress people - who are sometimes very reluctant to do so.
I advise them to ensure that piping anchors are as close as possible to the Tanks to keep loads to a minimum.
In our speciifcation we typically state the following:
****
Nozzle Loads
The Purchaser will supply details of loads resulting from connected piping. Vendor is to check these loads in accordance with API 650 - Appendix P or where tank diameter falls outside of the Appendix P limit vendor shall propose a suitable method of analysis for Purchaser approval.
Approval will only be granted where Vendor is able to demonstrate that the calculation method is appropriate to the tank and nozzle geometry, loadings and boundary conditions.
Vendor shall advise nozzle translations and rotations due to tank hydrostatic loading that shall be accommodated in Purchaser's pipng design.
*****
However Appendix P of API 650 is recommended only for tanks > 36 metres in diameter.
What happens when you have tanks < 36 metres in diameter? What would be the basis for checking nozzle loads on these smaller tanks?
Thanks
joe
I typically try to remove all nozzle loads to tanks as far as possible in agreement with our piping stress people - who are sometimes very reluctant to do so.
I advise them to ensure that piping anchors are as close as possible to the Tanks to keep loads to a minimum.
In our speciifcation we typically state the following:
****
Nozzle Loads
The Purchaser will supply details of loads resulting from connected piping. Vendor is to check these loads in accordance with API 650 - Appendix P or where tank diameter falls outside of the Appendix P limit vendor shall propose a suitable method of analysis for Purchaser approval.
Approval will only be granted where Vendor is able to demonstrate that the calculation method is appropriate to the tank and nozzle geometry, loadings and boundary conditions.
Vendor shall advise nozzle translations and rotations due to tank hydrostatic loading that shall be accommodated in Purchaser's pipng design.
*****
However Appendix P of API 650 is recommended only for tanks > 36 metres in diameter.
What happens when you have tanks < 36 metres in diameter? What would be the basis for checking nozzle loads on these smaller tanks?
Thanks
joe





RE: API Storage 650 Tanks - Nozzle Loads
interesting question....
For very small tanks, I have used WRC-107 as the basis for the check. This is limited because of the ratios between shell and nozzle diameters. You could also use FEA, I suppose, but it'll be expensive.
Although recommended for tanks>36m, I suppose one could apply the Appendix P for smaller tanks with the proviso that it is accepted by the purchaser (given that there is a potential abscence of other design rules). In any case, though, I agree wholeheartedly with your approach to eliminate as much as possible the nozzle loads on the tank wall. We have similar problems with pressure vessel design, where people will specify horrendous loads on nozzles which affect the thicknesses of the shells/heads. One then supplies a "very big, expensive pipe support-and not a vessel/heat exchanger". For some reason, though, piping & project management guys don't seem to see the humour in this statement
John
RE: API Storage 650 Tanks - Nozzle Loads
Your nozzle loading question has been around for a very long time. I remember it being raised in the early 1980s with regard to Condensate Storage tanks on a Nuclear power plant....The methodology detailed in API-650 actually only applies to a very few tank nozzles.
WRC 107/297 has been used in the past for nozzles within it's range of sizes. There are also finite element programs geared specifically for detailed nozzle evaluation (Nozzle/pro by the Paulin Research Group)
http://www.paulin.com/prg/nozzle_pro.htm
Another approach is to establish a "company wide" conservative acceptable loading chart with estimated forces/moments in three coordinates. This would only apply to API-650 tanks.
You will find that loads of about ~250D (forces) and ~300D (moments) are generally acceptable for nozzles of 4inch to 16 inch NPS ( where D is the nozzle size in inches and forces are in lbs.; moments in ft-lbs) This is just a rule of thumb....if nothing else is available
Just my opinion....
MJC
RE: API Storage 650 Tanks - Nozzle Loads
I agree with MJCronin (Mechanical) regards to WRC 107/297 has been used in the past for nozzles within it's range of sizes. There are also finite element programs geared specifically for detailed nozzle evaluation (Nozzle/pro by the Paulin Research Group)
Nozzzle PRo. , Also FE-PIPE has the API 650 TANK NOZZLE included.
Leonard@thill.biz
wwww.thill.biz
RE: API Storage 650 Tanks - Nozzle Loads
Expect to see some changes or alternatives to API 650 Appendix P sometime in the future (anyone know when the next edition is due?).
Take a look at a paper by Lengsfeld et. al. published at the 2002 Pressure Vessels and Piping conference:
PVP2002-1279
Stiffness Coefficients for Nozzles in API 650 Tanks Authors: Manfred Lengsfeld - Fluor Daniel Inc.
Kanhaiya L. Bardia - Fluor Daniel Inc.
Jan Taagepera - Valero Refining Co.
Kanajett Hathaitham - Fluor Signature Services Inc.
Donald G. LaBounty - Fluor Daniel Inc.
Mark C. Lengsfeld - Lengsfeld Crane Valves
You can purchase the entire volume, PVP-Vol. 440, or for $15 you can get a .pdf of the paper from
http://store.asme.org/product.asp?catalog%5Fname=Confer...
The paper covers nozzle loadings in tanks for 6" thru 48" nozzles in 30' to 300' diameter shells.
jt
RE: API Storage 650 Tanks - Nozzle Loads
jt