Based on code ASME B31.3, flexibility analysis in the piping system needs formal analysis or does not need formal analysis. Piping system can be does not need formal analysis it meet the following requirement:
- Piping system is a duplicate of an existing piping system, which is in operation showed a satisfactory performance.
- Piping system can be judged easily that has sufficient flexibility when compared with the flexibility of existing piping system which had been analyzed before.
- Piping system with uniform size, which is supported by only two support without any restraint point between them and meet the empirical equation as following below:
(Dy / (L-U)2) ≤ K1
Where:
K1 = 208000 SA/Ea (mm/m)2
U = anchor distance, straight line between anchor, m
L = developed length of pipe between anchor, m
Y = resultant of total displacement strain to be absorbed by piping system, mm
D = outside diameter of pipe, mm
Ea = reference modulus of elasticity at 201 C (700 F), Mpa
SA = allowable displacement stress range, Mpa
While a piping system can be said require for analysis of flexibility when meeting the following requirements:
- Piping system that does not meet of the three requirements above must be analyzed by one of methods analysis of the following: simple analysis method, approximate analysis method or comprehensive analysis method.
- Comprehensive analyses that are acceptable include analysis method and method that use charts which can calculate force, moment and stress which is caused by the displacement strain.
- The factors of stress intensity in piping component except straight pipe must be taken into calculation in comprehensive analysis method.
- In the flexibility analysis, all of piping components between two anchor points must be analyzed as a complete system.