ANTICIPATED SUSTAINED CONDITIONS CONSIDERING PIPE LIFTOFF
1ANTICIPATED SUSTAINED CONDITIONS CONSIDERING PIPE LIFTOFF
1.1 Problem definition
As same as in the first ASMEexample (Chapter Fehler: Referenz nicht gefunden) a code complient analysis of a piping system is to be performed. Special consideration has to be given to the fact that one support lifts up during operation.
Figure 2: Rohr2 Model
Figure 1: Model by ASME
1.2 References (ASME B31.3)
ASME B31.32008 Process Piping (ASME Code for Pressure Piping, B31)
Revision of ASME B31.32006, The American Society of Mechanical Engineers, New York, NY, Appendix S, pg. 286289
A beam system with design and operating conditions under the effect of gravity. The pipe components are defined by ASME. The following listed values are used:
Where:
Variable 
Description 
Unit 
Used Value 
Pipe material 
 
ASTM A 106 Grade B 

Outside diameter (NPS) 
mm 
406,4 

Inside diameter 
mm 
390.54 

Cross section 
mmÂ² 
9933,15 

Section Modulus 
mmÂ³ 
970567,7 

Nominal wall thickness 
mm 
9,53 

Insulation thickness 
mm 
127 

Insulation density 
kg/mÂ³ 
176 
Corrosion allowance 
mm 
1,59 

Bend radius 
mm 
609,5 

Pipe density 
kg/mÂ³ 
7833,4 

Unit weight 
kg/m 
248,3 

Fluid specific gravity 
kg/mÂ³ 
1000 

Number of cycles 
 
< 7000 

Stress range factor 
 
1 

Installation temperature 
Â°C 
21 

Modulus of Elasticity 
N/mmÂ² 
203010 

Poisson's ratio 
 
0,3 

Design pressure 
bar Ã¼ 
39,68 

Design temperature 
Â°C 
302 

Operating pressure1 
bar Ã¼ 
37,95 

Operating temperature1 
Â°C 
288 

Operating pressure2 
bar Ã¼ 
0 

Operating temperature2 
Â°C 
1 

Horizontal support loads 
N 
 

Vertical support loads 
N 
 

Moments at supports 
Nm 
 

Axial section force 
N 
 

Vertical section force 
N 
 

Bending moment 
Nm 
 

Axial force 
N 
 

Bending moment (InPlane) 
Nm 
 

Bending moment (OutPlane) 
Nm 
 

Torsional moment 
Nm 
0 

Longitudinal stress 
N/mmÂ² 
 

Pressure induced stress 
N/mmÂ² 
45,76 

Allowable stress at maximum metal temp. 
N/mmÂ² 
130 

stress intensification factor (OutPlane) for branch 
 
2,14 

stress intensification factor (InPlane) for branch 
 
2,57 
Table 1: Overview of the used variables
1.3 Model description (ROHR2)
The known system geometry from the previous example is used. A few modifications must be taken into account. The this example consists of the same geometry as in the eleventh, but it is mirrored at the vertical axis. Hence of this, the calculated system is symmetric. The example has a total length of 61 meters. It consists of steel pipes (ASTM A 106 Grade B). The calculation model has four rigid anchors and two sliding supports. All supports have indefinite stiffness. The ASME example contaons a slide support at node 50 which lifts up. The ASMECode regards several listed sustained load conditions, but it evaluates just one of them. In this case, the support at node 50 mustn't be attached. The following specific parameter are equal to the previous example:

Characteristic material values

Pipe density, Poisson's ratio, modulus of elasticity, mean coefficient of linear thermal expansion and basic allowable stresses


Dimensions

Corrosion allowances

Insulation parameters

Load cases and their properties

Stress analysis conditions
A detailed list of the input parameters of the model is given in the table above.
1.4 Result comparisons
The following tables compare only two adequately points of each verification value. These results apply to the sustained load condition 3 (Appendix S, page 289) where the support status of node 50 had to be deactivated.All results are given in a global coordinate system. The whole comparison is shown in the document R2_stresses12.ods.
1.4.1 Results for operating case 1
Figure 4: ROHR2 model (detail) with force
Figure 3: Support loads, node 10
Figure 6: ROHR2 model (detail) with force
Figure 5: Support loads, node 20
Point 
Value 
Reference (ASME) [N] 
Rohr2 [N] 
Difference [%] 
10 
26600 
26590 
<0,04 
Table 2: Comparison of the horizontal support load for node 10
Point 
Value 
Reference (ASME) [N] 
Rohr2 [N] 
Difference [%] 
10 
14050 
14058 
<0,06 

20 
58900 
58966 
<0,12 
Table 3: Comparison of the vertical support load for node 10, 20
Point 
Value 
Reference (ASME) [Nm] 
Rohr2 [Nm] 
Difference [%] 
10 
27000 
26967 
<0,13 
Table 12.4.1.3: Comparison of the moments at supports for node 10
1.4.2 Sustained load case results 1
Figure 7: sectional results, node 40m
Figure 8: sectional results of node 30n
Point 
Value 
Reference (ASME) [N] 
Rohr2 [N] 
Difference [%] 
30n 
12575 
12595 
<0,16 

40m 
12575 
12595 
<0,16 
Table 4: Comparison of the axial section force for node 30n, 40m
Point 
Value 
Reference (ASME) [N] 
Rohr2 [N] 
Difference [%] 
30n 
34985 
35027 
<0,12 

40m 
21952 
21971 
<0.09 
Table 5: Comparison of the vertical section force for node 30n, 40m
Point 
Value 
Reference (ASME) [Nm] 
Rohr2 [Nm] 
Difference [%] 
30n 
29985 
30062 
<0,26 

40m 
32770 
32850 
<0.25 
Table 6: Comparison of the Bending Moment for node 30n, 40m
1.4.3 Sustained load case results 2
Figure 9: SL results at node 30n
Figure 10: SL results at node 40m
Point 
Value 
Rohr2 [N] 
30n 
35027 

40m 
24442 
Table 7: Converted axial force of node 30n, 40m
Point 
Value 
Rohr2 [N] 
30n 
30062 

40m 
32850 
Table 8: Converted in or outplane moments of node 30n, 40m
Figure 11: ROHR2 model with SLstresses
Point 
Value 
Reference (ASME) [N/mmÂ²] 
Rohr2 [N/mmÂ²] 
Difference [%] 
30n 
101,920 
109,000 
<6.5 

40m 
108,525 
113,500 
<4.4 
Table 9: Comparison of the longitudinal stresses for node 30n, 40m
1.5 Conclusion
The results for all points are listed in the R2_stresses12.ods document. Only one half of the system was documented because of the pipe and load symmetry. The results are close to the reference. The reasons for the differences are the same as in the previous example.
1.6Files
R012_inch.r2w
R012_mm.r2w
R2_stresses12.ods
MATDAT.r2u
SLBer.Pkt.10.mcd
SLBer.Pkt.20.mcd
SLBer.Pkt.30n.mcd
SLBer.Pkt.40m.mcd
SLBer.Pkt.50.mcd
SIGMA Ingenieurgesellschaft mbH www.rohr2.com