Hi again @fplatteau,
I am not an expert in this but could you not just use this formula:
Rho = Density of the fluid [kg/m³],
K_f = Bulk Modulus of the fluid [N/m²],
E_R = Young’s Modulus of the pipe [N/m²],
d_i = Inner diameter of the pipe [m],
s = Thickness of the pipe [m]
mu = Poisson’s ratio of the material
Assuming that the Bulk Modulus is the unknown you could simply rearrange the formula, can’t you?
Tell me if I am mistaken.
Source of the formula: Druckstoß - Wikipedia