you ca follow the following references for detailed procedure to control noise leves in piping sysem used for industrial purposes
A licensee shall operate pipeline facilities and conduct pipeline construction and operations in accordance with the maximum noise level limitations specified by the Regulator in Directive 038.
Abstract from PIPELINE ACT; PIPELINE RULES;Alberta Regulation 91/2005
With amendments up to and including Alberta Regulation 159/2013
Pipeline Rules of Thumb Handbook: A Manual of Quick, Accurate Solutions to ...
By E.W. McAllister
ISO/FDIS 15664; Acoustics-Noise control design procedures for open plant, 2001
Grannerman J.H., Jansen RPM., Sound power deterimination of large open plants, comparison of alternative methods, Internoise, 99, 1999.
Guide for measuring and calculatig insdustrial noise guideline issused by Dutch mininstry of envirnoment, April, 1999.