1ANTICIPATED SUSTAINED CONDITIONS CONSIDERING PIPE LIFT-OFF

1.1 Problem definition

As same as in the first ASME-example (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 B31.3-2008 Process Piping (ASME Code for Pressure Piping, B31)

Revision of ASME B31.3-2006, The American Society of Mechanical Engineers, New York, NY, Appendix S, pg. 286-289

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	mm²	9933,15
	Section Modulus	mm³	970567,7
	Nominal wall thickness	mm	9,53
	Insulation thickness	mm	127
	Insulation density	kg/m³	176

	Corrosion allowance	mm	1,59
	Bend radius	mm	609,5
	Pipe density	kg/m³	7833,4
	Unit weight	kg/m	248,3
	Fluid specific gravity	kg/m³	1000
	Number of cycles	---	< 7000
	Stress range factor	---	1
	Installation temperature	°C	21
	Modulus of Elasticity	N/mm²	203010
	Poisson's ratio	---	0,3
	Design pressure	bar ü	39,68
	Design temperature	°C	302
	Operating pressure1	bar ü	37,95
	Operating temperature1	°C	288
	Operating pressure2	bar ü	0
	Operating temperature2	°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 (In-Plane)	Nm	---
	Bending moment (Out-Plane)	Nm	---
	Torsional moment	Nm	0
	Longitudinal stress	N/mm²	---
	Pressure induced stress	N/mm²	45,76
	Allowable stress at maximum metal temp.	N/mm²	130
	stress intensification factor (Out-Plane) for branch	---	2,14
	stress intensification factor (In-Plane) 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 ASME-Code 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 out-plane moments of node 30n, 40m

Figure 11: ROHR2 model with SL-stresses

Point	Value	Reference (ASME) [N/mm²]	Rohr2 [N/mm²]	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

SL-Ber.Pkt.10.mcd

SL-Ber.Pkt.20.mcd

SL-Ber.Pkt.30n.mcd

SL-Ber.Pkt.40m.mcd

SL-Ber.Pkt.50.mcd