READING A SELECTION TABLE FOR VARIABLE SPRINGS
A pipe has a hot load of 636 Kg with pipe movement limited to 20mm (from cold to hot load) and a maximum variability of 25%. Which hanger is appropriate for this piping system?6
1. The actual load 636Kg lies within the size 10 variable spring support on the table above.
2. The next step is to confirm the variability.
3. From the AG680 working range, the lowest spring rate is 9.2 Kg/mm
4. Variability (%) = Movement X Spring rate / Hot Load X 100
20 * 9.2 / 636 * 100 = 29.3%
Which means the variability is beyond the allowable limit of 25%
5. The next working range on the table is the AG700, and the spring rate is 4.6Kg/mm
Variability = 14.5%, which lies within the acceptable limit. Therefore, the right variable spring support size is AG700, size 10.
6. The cold load for the system will be Cold Load = 636 – 20 * 4.6= 544
7. The actual (hot load) is 636Kg and the cold load is 544Kg