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The following warning appears when inserting Nozzle, how to resolve?
---------------------------Warning ---------------------------W41-27: Parameters are outside the applicable range---------------------------OK ---------------------------
What should I do to avoid this warning message?
One should understand the limitations of the codes:Each method has a limited applicability based on certain parameters. Unfortunately AutoPIPE does not mention which limit caused the message. Values shown may still be reasonable outside the range. You may try other methods such as ASME or Bijlaard.
a. d/D <= 0=0.33 (subsequent revisions extend d/D <= 0.50) b. D/T <= 600 c. Spherical shell limit: d/D = 0.33
API 650 Method is limited to horizontal nozzles on vertical tanks of diameters in the order of approximately 100 ft (large tanks). For nozzles on the spherical or torispherical head, you need to use "Spherical" nozzle option. As ASME method is typically meant for reducing tee branches.
You would need to check the code to see the formulas. Actually they are plots.
There are limits on these 3 ratios for API 650:
ALFA = Vessel radius / Vessel thickness BETA = Nozzle radius / Vessel radius GAMA = Nozzle center line above Tanks Bottom (L) / (2 * Nozzle Radius)
Limits are exceeded if:
1 = ALFA > 2300 2 = ALFA < 400 3 = BETA > 0.04 4 = BETA < 0.005 5 = GAMA > 1.5 6 = GAMA < 1.0
For those who do not have a reinforcement pad for the nozzle, try other options (WRC297 or Bijlaard) or use larger stiffness to be conservative.
a. d/D <= 0.50 b. 20 <= D/T <= 2500
where: d = outside dia of nozzle D = outside dia of shell T = shell thickness
AutoPIPE also considers limits of the WRC297 stiffness curves on Fig 59 and 60 and giving a warning if any of these limits is exceeded. The program proceeds to calculate stiffnesses at the last known curve value which may or may not be valid.
Radial, longitudinal and circumferential stiffness
Lambda < 0.1
Lambda > upper limit of curves
where: Lambda = (d/D).SQRT(D/T)
D - vessel mean diameter T - thickness of shell <<<<< Is this including or not including re-pad thickness if there is one? d - nozzle diameter t - nozzle thickness
T/t <0.2 or T/t > 10
Delta > 100 or Delta < 14 T/t < 1.0 or T/t > 10
delta = L/sqrt(DT)
L = length of vessel L = 8L1L2/((sqrt(L1) + sqrt(L2))^2) - for off-center nozzle
Note: WRC297 has no concept of reinforcing pads, the thickness field in the dialog is for shell only (i.e. uniform shell thickness). If you enter shell + pad thickness, this would be stiffer and more conservative to calculate the nozzle flexibility.
gama > 15 (murad and sun limits 10-150, 15-300 in bijlaard figs) beta < 0.55 (0.55 in murad and sun paper, 0.25 in bijlaard figs)
Where: gama = rad / th beta = c / rad
c = nozzle outside radius rad = vessel outside radius th = vessel thickness
1. u < 20 curve values 2. r/t > 15 page 3 of paper 3. ro/r < 0.55 (murad and sun curves - cylindrical)
rad = outside radius t = thick `vessel thickness <<<<< Is this including or not including re-pad thickness if there is one? r = rad - 0.5*t `mean radius of vessel ro = piprad/2.0 nu = poison e = ymod c1 = (12.0*(1.0-nu^2))^0.25 ! c1=1.81784 for nu=0.3 u = c1*ro/sqrt(r*t)
Warnings Messages displayed in AutoPIPE