standarizing nozzle loads for vessels

mahsud44 · Dec 13, 2010

Hi all,

We are a pressure vessel manufacturing company, I want to standardize the nozzle loads for our steam drums for a range of pressure and temperatures.
Can you guys please tell me what is the procedure to standarize the nozzle allowable loads for the nozzles of a vessel so that when piping team designs piping they can use those allowable loads and do the piping at their end.

C2it · Dec 14, 2010

Pressure vessel design codes don't normally address this. Most lists of allowable nozzle loads originate from design or construction companies. An exception is Norsok Standard R-001, available free from Norsok's website. It has equations limiting loads according to size and pressure class, but does not consider temperature. Look at section 5.1.5 in the 1997 edition.

saplanti · Dec 14, 2010

It may be too difficult to standardise the nozzle loads on the drums due to the variations on the pressure (LP, HP drums) and thicknesses. Mainly LP drums are the most disadventages due to the less thickness.

If HP drum thickness was selected for the tube efficiencies you may not have too much problem in getting the piping loads by the shell wall if you select the location of the nozzle on the untubed side.

In case the HP drum wall thickness was welected for internal pressure only (no tubing), you may need to assume some pre-loads and check by calculation (WRC 297, PD5500 or FE-Pipe),and assign the acceptable & reasonable loads to the piping section.

Mainly the drum nozzle acceptable loads are very limited, and pipe should have sufficient flexibility.

Most of the large nozzle loads come from the inproper pipe/tube arrangement. I guess working on that side will eliminate large loads on the nozzles.

Ibrahim Demir

saplanti · Dec 14, 2010

I would like to add the variation on the materials and their properties as well for the drum construction.

Ibrahim Demir

MrBTU · Dec 15, 2010

API 662 gives a method for assigning loads for general and severe duty based on nozzle diameters. You may find this useful. I've used it in the past when customers ask for loads but do not know what they want.
TEMA says that laods will be assumed at zero for design unless the customer gives us values.

SnTMan · Dec 15, 2010

mahsud44, HEI Standards for Powerplant Heat Exchanges contains a simplified method for finding the allowable resultant moment and shear load for a given geometry and material.

Practically speaking it is of little use, but it might meet your needs.

Nozzle loads can (and usually do) consist of three loads and three moments applied simultaneously, see WRC 107 for example, and you can only evaluate particular load cases, not determine allowables.

Regards,

Mike