Buried flexible pipes: design considerations in applying AS2566 Standard

AS/NZS 2566.1 (1998) standard for buried pipes neither represents the current state of practice nor is it accurate with respect to ground parameters provided therein. The values referred to as soil modulus in this Standard provides confusion in the industry. The standard incorrectly equates an embedment modulus (which is a soil – pipe modulus reaction) and a native soil modulus. These are then combined into an effective soil modulus. Typically for flexible pipes, over 85% of its calculated performance is dependent on the installation procedure which affects the soil stiffness. The soil-pipe stiffness is secondary to the soil stiffness. The equation used in calculating the pipe deflection has limitations. The Standard is also currently dated in terms of guidance on allowable deflection and properties for the types of pipes currently available in the market.