Compressor piping is a dominant noise source in petrochemical plants with large centrifugal compressors. Acoustic insulation is used on compressor suction, discharge and recycle lines as a measure to mitigate noise radiating from compressor piping. This paper will demonstrate using case studies the importance of acoustic insulation on compressor piping as the primary and most cost effective noise control method for both community and in-plant noise. Case studies include the predicted and measured noise levels obtained during post startup noise surveys. This paper will also illustrate that to obtain good agreement with measured noise levels it is imperative to accurately model the piping sources following the actual piping layout and account for distance attenuation. A cost-benefit analysis of using complete compressor houses and/or acoustic blankets will be presented along with the efficacy of various types of acoustic insulation including elastomeric foam and aerogel based insulation systems. Different acoustic requirements for hot and cold insulation systems will also be presented.