For ISO 14692 2017, specifies a factor for design life, A0, for FRP pipe. The software uses A0 as a multiplier for the expected lifetime value of the pipe. For example, an A0 value of 1 with expected lifetime at the typical default value of 20 years results in a design lifetime of 20 years.
If you want a longer lifetime, then use a smaller value of A0 to reduce the allowable stress limits. A smaller value of A0 creates a smaller operating envelope, making it harder for the pipe system to pass requirements imposed by the modified envelope and extending the design lifetime. You must separately calculate the value of A0 as defined by the code.
If you do not define this value, the software uses the default value of 1.0. The maximum value is 1.0.
Example
Determine A0 to achieve a design lifetime of 30 years for GRE pipe operating at the default temperature of 149° F (65° C).
According to the code:
A0 = (20 yrs/30 yrs)^Gxx
where
Gxx = a parameter depending on the resin system and operating temperature
From Table A.1 in ISO 14692-2:2017, Gxx = 0.065
thus
A0 = 0.974