Applies To Product(s): AutoPIPE Version(s): V8i Environment: N/A Area: Modeling Subarea: Original Author: Darius Rimasauskas, Bentley Technical Support Group Error or Warning Message 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? Answer One should understand the limitations of the WRC codes: WRC107: 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 WRC297: a. d/D = 0.50 b. 20 = D/T = 2500 where: d = outside dia of nozzle D = outside dia of shell T = shell thickness 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. API650 method 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 LOCATION ABOVE GROUND LEVEL/(2*NozzleRadius) 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. WRC297 method Autopipe is considering limits of the WRC297 stiffness curves on Fig 59 and 60 (Copies attached) 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 mean diameter t - nozzle thickness Longitudinal stiffness T/t 0.2 or T/t 10 Circumferential stiffness 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. Bijlaard method Bijlaard Nozzle limits Cylindrical 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 Spherical 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)
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