Proposed Pipe Size To Be Used :

SURE-LINE High Density Polyethylene Pipe (HDPE):

Other Properties :

Wall Thickness 0.3125 inches
Outside Diameter (O.D.) SURE-LINE 7.8280 inches
Inside Diameter (I.D.) SURE-LINE 7.2030 inches

Existing Steel Pipe :

Original Wall Thickness 0.331 inches
Weight of Pipe 26.68 lbs/lf
Strength 145.00 psi
Outside Diameter (O.D.) 8.740 inches
Inside Diameter ( I.D.) 8.079 inches
Modulus of elasticity:    
  tension 15,000,000 psi
  Compression 6,000,000 psi

Calculation of Design Pressure:

The maximum pressure determined by 49 CFR 192.123 for a single plastic pipe is:
100 psi
The lowest operating temperature for plastic pipe as per code is:
-29 ° C, -20 ° F

Maximum operating temperature at 100 psi pressure class for Thermoplastic (DOT limits) ; wall thickness minimum 1.57mm (0.062 inches) is:

60 ° C, 140 ° F

The design pressure for gas lines is determined According to AGA formula as follows:

P= 2*S*F/(R-1) – 2*S*t*F/ (D-t)
T= PD/(P+2*S*F)  
Design Pressure P = ? psi
Outside Diameter D= 7.828 inches
The Long Term Hydrostatic Strength S= 1.600 psi
The Wall Thickness t= 0.313 inches

The design factor used to compensate for stresses other than internal pressure, such as bending in installation, earth loading, subsidence, temperature changes and fitting compressions, all applicable to freely buried plastic pipe, is allocated to be 0.32 by GA CFR 192.121.

In absence of the factor determined for SURE-LINE pipe, which is restrained pipe, the design factor will be:

F= 0.50