Surges [per day] |
Surges [per hr] |
Surges [per 50 years] |
Surges [per 100 years] |
---|---|---|---|
1 | 0.04 | 18,263 | 36,525 |
10 | 0.42 | 182,500 | 365,00 |
40 | 2 | 730,000 | 1,460,000 |
75 | 3 | 1,368,750 | 2,737,000 |
150 | 6 | 2,637,500 | 5,475,000 |
250 | 10 | 4,562,500 | 9,125,000 |
300 | 13 | 5,478,750 | 10,957,500 |
The design of a piping systems requires engineers and systems owners to set an acceptable design pipe life. Typically a water pipe design life is set between 50 to 100 years. For PVC and PE pipes the cumulative number of fatigue cycles will determine the pipe design life. PPI-PACE defaults to 55 cycles per day and allow values greater than and equal to 55 cycles per day. PPI-PACE defaults values are reasonable and realistic for most watermain and forcemain designs.
Datum | Source | Reference | Comments |
---|---|---|---|
55 cycles/day | ANSI/AWWA C900-07 | Polyvinyl Chloride (PVC) Pressure Pipe and Fabricated Fittings, 4in. Through 12In. (100mm through 300 mm), for Water Transmission and Distribution Appendix B Recurring (Cyclic) Surge-Figure and Design Example Page 23 | Section B.2: Design Example Anticipated cycles per day = 55 |
54 cycles/day | AWWA C905-10 | Appendix B Recurring (cyclic) Surge - Figures and Design Examples Section B.2: Design Example | Page 27 Total # of cycles = factor of safey *(# cycles per day) * (365 days/year) = 2 *54*(365*50) = 2 million cycles in 50 years Note: 54 cycles per day |
48 - 192 cycles/day | Charlotte Mecklenburg Utilities | Wastewater Pumping Station Standard Specifications Section 2.04 Cycle and Pump Run Times A 2 page 6 | Pumps shall be designed to operate between two and eight times per hour at a design daily flow |
96 - 120 cycles/day | Charlotte Mecklenburg Utilities | Wastewater Pumping Station Standard Specifications Section 2.04 Cycle and Pump Run Times A 2 page 6 | with a strong preference for 4 to 5 cycles per hour |
116 cycles/day | Uni-Bell 2012 | Fifth Edition Handbook of PVC Pipe Design and Construction Page 5.44 | Example 5.5 14in. AWWA Force main page 5.47 N=58 starts+ 58 stops = 116 cycles/day |
96 cycles/day | Performance Pipe | Bulletin PP402-4710 | 1 cycle every 15 minutes = 96 cycles/day |
The design of PVC and PE pressure pipe requires the system recurring surge flow velocity or normal systems operational flow. The design Recurring Surge pressure is estimated using the change in water velocity resulting from sudden stoppage of the operational (normal) design flow. Graphs and Tables below summarize available water design guides and reports, water design standards, and utility and forcemain specifications, which provide guidance on realistic recurring surge flow velocities.
The design of PVC and PE pressure pipe requires the system Occasional surge flow velocity. The design Occasional Surge pressure is estimated using the change in water velocity resulting from sudden stoppage of the design flow. Graphs and charts below summarize available water standards, design guides, design reports and water utility specifications, which provide guidance on realistic occasional surge flow velocities.