Internal Pressure Design Calculator

This calculator enables engineers to determine PVC pipe pressure class and wall thickness for various internal pressure limit states. The user inputs values for the three pressure design checks found in Chapter 5 of the Handbook of PVC Pipe Design and Construction and the acceptance test requirement in accordance with AWWA C605. Designers are responsible for the proper use of this program for all projects. The design checks are as follows:

• WP ≤ PC x F_T
• WP + P_RS ≤ PC x F_T
• WP + P_OS ≤ 1.6 x PC x F_T
• P_ft ≤ PC x F_T

Where :

• WP = Working Pressure, Maximum Steady State Operating Pressure
• PC = Pressure Class
• P_RS = Recurring Surge
• P_OS = Occasional Surge
• P_ft = Field Hydrostatic Test Pressure
• F_T = Temperature Coefficient

Recurring surges occur during a pump station’s normal on-off operations and are typically considered for sewer force main or water transmission main applications. Pumps with variable-frequency drives as well as other transient control devices can reduce recurring surge pressures. Water distribution mains do not usually consider recurring surge events for their design (therefore, P_RS would equal 0).

Occasional surges occur during a worst-case scenario (such as a component power failure) that leads to a sudden stoppage of maximum flow velocity.

NOTE: This calculator only checks PVC pressure pipe capacity for the above limit states. It does NOT check for design life from cyclic pressures. To check for cyclic design life, use the online cyclic calculator (coming soon). Please contact Uni-Bell for more information.