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Numerical examples given below illustrate both these algorithms for design of spring hanger supports. A first example (Figure 3) is a fragment of the conventional power plant Main Steam Line located between two fix points: boiler header and turbine stop valve. This system, designed more than 20 years ago, has a typical floating design: heavy and flexible pipe is suspended between two anchor points by spring hangers only.

Figure 3 Numerical examples given below illustrate both these algorithms for design of spring hanger supports. A first example (Figure 3) is a fragment of the conventional power plant Main Steam Line located between two fix points: boiler header and turbine stop valve. This system, designed more than 20 years ago, has a typical floating design: heavy and flexible pipe is suspended between two anchor points by spring hangers only.

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Tables given in Annex A demonstrate results of spring's selection procedure performed according to the above algorithms. Springs were selected from LISEGA 2010 Catalogue. In both cases a target load variation criteria was set to 25%. Each selected spring is designated as “X/Y”, where X — spring size, Y —travel range (1.e. designation “4/3” corresponds to LISEGA type number “214328”).
Tables given in Annex A demonstrate results of spring's selection procedure performed according to the above algorithms. Springs were selected from LISEGA 2010 Catalogue. In both cases a target load variation criteria was set to 25%. Each selected spring is designated as “X/Y”, where X — spring size, Y —travel range (1.e. designation “4/3” corresponds to LISEGA type number “214328”).
Iterative algorithm (Table 2) in contrast to the traditional one utilizes real values of load variation and problems described above are not appear. Although the theoretical variability var(Ro) is much higher than 25%, the actual variability is in the specified limits. Moreover, comparison of results from Tables 1 and 2 leads to conclusion that iterative algorithm provides more compact and economic springs for hanger supports.
Iterative algorithm (Table 2) in contrast to the traditional one utilizes real values of load variation and problems described above are not appear. Although the theoretical variability var(Ro) is much higher than 25%, the actual variability is in the specified limits. Moreover, comparison of results from Tables 1 and 2 leads to conclusion that iterative algorithm provides more compact and economic springs for hanger supports.
As the next step of this study influence of the above effects on the calculation of sustained stresses is considered. Before Table 5
As the next step of this study influence of the above effects on the calculation of sustained stresses is considered. Before Table 5
Unlike first example influence of spring stiffness on the vertical movements is significantly less. Same piping system but with changed support configuration is considered in Example 2. Rigid hanger supports are installed instead of spring hangers NN 07, 10, 13 and support N 06 is excluded as shown in Figure 4.
Unlike first example influence of spring stiffness on the vertical movements is significantly less. Same piping system but with changed support configuration is considered in Example 2. Rigid hanger supports are installed instead of spring hangers NN 07, 10, 13 and support N 06 is excluded as shown in Figure 4.
Modified Hot support configuration algorithm This algorithm is used in Russia for the design of power piping since middle seventies [3]. Analysis starts from the hot This algorithm performs first two load cases for cold (LC1) and hot (LC2) loads. Then, additional "free thermal case" is executed (LC3). This load case assumes weightless piping. Sustained stresses (LC4) are calculated as difference between LC2 and LC3. And simultaneously expansion stresses (LCS) are calculated as difference between hot and cold loads.
Modified Hot support configuration algorithm This algorithm is used in Russia for the design of power piping since middle seventies [3]. Analysis starts from the hot This algorithm performs first two load cases for cold (LC1) and hot (LC2) loads. Then, additional "free thermal case" is executed (LC3). This load case assumes weightless piping. Sustained stresses (LC4) are calculated as difference between LC2 and LC3. And simultaneously expansion stresses (LCS) are calculated as difference between hot and cold loads.
Example 1. Selection of springs according to iterative algorithm (floating design).
Example 1. Selection of springs according to iterative algorithm (floating design).
Example 1. Selection of springs according to one step algorithm (floating design). Table 2
Example 1. Selection of springs according to one step algorithm (floating design). Table 2
Example 2. Selection of springs according to one step algorithm (rigid design).
Example 2. Selection of springs according to one step algorithm (rigid design).
Example 2. Selection of springs according to iterative algorithm (rigid design).
Example 2. Selection of springs according to iterative algorithm (rigid design).
Related topics:
Piping Flexibility and Stress Analysis
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