Numerical simulations for calculating the insertion loss of pipeline insulation

ISO 15665:2003 defines the acoustic performance of three classes (classes A, B and C) of pipe insulation. Furthermore, it defines a standardized test method for measuring the acoustic performance of any type of construction, thereby allowing existing and new insulation constructions to be rated against the three classes. At the same time the understanding of all physical mechanisms that occur during the wave propagation in such a kind of multilayer structures is not complete yet. As general rule in a correct sound insulation design for piping applications, the configuration must comprise three different mechanisms: sound barrier, de coupling and absorption/dissipation. It is thus of fundamental importance to find the best compromise among the above mentioned mechanisms in order to fulfill and optimize any acoustical and thermal requirements in real applications. Aim of the present work is to define a fully numerical procedure (transfer matrix approach) for simulating and optimize the insertion loss of such a kind of piping systems once mechanical and physical properties of any single layer have been experimentally measured. Special attention will be paid to analysis of mechanical behavior of open and closed cell materials and cladding materials largely utilized for increasing the insertion loss of a bare pipe. Results will be presented and discussed for several multilayer lay-outs and compared with experimental tests carried out according the above mentioned ISO standard.