HDPE Pressure Pipe Occasional and Recurring

Surge Design ConsiderationsMark Knight PhD, P. Eng.

University of Waterloo

Camille George Rubeiz, P.E.Plastics Pipe Institute

Larry Petroff, P.E.Plastic Pipe Consultant

1

Developers of Industry Leading Design Tools• BOREAID –

• Full commercial licenced HDD design tool – Fall 2013 a Vermeer Product

• free web based HDD PE pipe design tool – limited version of BOREAID

• free web based HDPE and PVC pressure pipe calculator that follows ASTM and AWWA standards

2

Disclaimers

• I am a product independent academic and researcher

• I am not paid to represent any pipe manufacturers or suppliers

3

Confused Plastic Pipe Industry

Different terminology for HDPE and PVCPressure Class (PC) vs Pressure Rating (PR)DIOD, CIOD, IPS, DIPS

HDPE vs PVC marketing

Lack of industry understanding of ASTM and AWWA design methods

4

HDPE and PVC Pressure Pipe Design Standards

ASTM F714

AWWA C901 AWWA C906

AWWAC900/C905

PE3608 PE3608 PE3608 PVC12454PE 4710

@ 1000 psiPE 4710

@1000 psiPE4710 @800 psi

PVC12454@ 2000 psiPVC12454

HDPE Pipe Resin = PE3608 and PE4710PVC Pipe Resin = PVC12454

5

Plastic Pressure Pipe Design

Complete Life Cycle Design Analysis

Fatigue – Determine No. of cycles to failure over design life

Complete Operational Design

Working and Surge Pressure Analysis

PIPE Design Input Properties

Velocity Min ID Flow Pressure Disinfectant

6

Working Pressure Design

7

Hydrostatic Design Stress (HDS)

HDPE PVCASTMF714

AWWAC901

AWWAC906

AWWAC900/C905

PE4710 1000psi 800psi

PE3608 800psi

PVC12454 2000psi

8

Pressure Class (PC) @ 73oF

PC = 2 HDS/(DR-1)

HDS = Hydrostatic Design StressDR = Dimension Ratio = OD/tmin

9

Allowable Pressure Design

HDPEAWWA M55

PVC AWWA

C900/C905WPR PC x FT

WPR + Pos 2.0 x PC x FT 1.6 x PC x FT

WPR + PRS 1.5 x PC x FT PC x FT

WPR = Working Pressure RatingPOS = Occasional SurgePRS = Recurring Surge Temperature Factors (FT)

10

Temperature Factors (FT)

HDPEAWWA M55

PVC AWWA

C900/C905FT

Continuous Long-Term Temperature FT

1.0 < 81oF 80oF 0.880.9 81 – 90oF 90oF 0.750.8 91-100oF 100oF 0.62

11

Allowable Design Pressure ExamplePC = 2 HDS/(DR-1)

HDPE DR-17

PVC DR-18

ASTM F714

AWWA C901

AWWA C906

AWWA C900C905

PE 4710 125 psi 100 psi

PE 3608 100 psiPVC

12454 235 psi

12

Surge Design (Wing Flex Design)

What are the major design Issues for Wing design?

13

Typical Pressure Fluctuation from Sudden Valve Closure in DR 11 Pipe

Load Rate ~ 120 psig/sec

G.P. Marshall, S. Brogden, M.A. Shepherd (1998) “Evaluation of the Surge and Fatigue Resistance of PVC and PE Pipeline Materials for use in the U.K. Water Industry”, 

Plastics Pipe X, Goteburg, Sweden

Time (seconds) 

Pressure (bar) 

14

Surge Design

Design system such that it can withstand the highest expected surge load event over its

design life

While a full transient analysis is recommended, a full flow stoppage at the max. flow velocity provides a good basis for considering surge

events.

15

Surge - Analysis

Joukowsky Equation: Ps = a(ΔV/2.31g)

Ps = surge (psi)a = wave velocity (ft/s)ΔV = change in velocity (fps)g = acceleration due to gravity (32 ft/sec2)

16

What are Typical Network Water Velocities?

Jana Lab survey of 51 water utilities determined: Average Maximum Design Velocities for Normal Flow

Average Maximum Design Velocities for Fire Flow

17

Jana Lab Water Velocity Survey

0

5

10

15

20

25

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51

Maximum Design Velocity for Normal Flow

(fps)

Average = 6.7 fps

http://plasticpipe.org/pdf/mid-fatigue-plastic-water-pipe-01-12-12

Fatigue Design

Recurring surges:

frequently occurring surges caused by normal pipe operations like opening and closing of pumps and valves, … AWWA PE M55

“may occur up to millions of times in a piping system’s lifetime” AWWA PVC C905-10

19

Fatigue Design

Occasional surges:

Caused by emergency operations

Often “the result of a malfunction, such as a power failure or system component failure …” AWWA PE M55

20

PVC Fatigue Design

PVC design fatigue life is determined using AWWA C900 and C905 Appendix B.

Well established method but not well understood in the industry.

Often not performed due to analysis complexity and lack of industry understanding

21

PVC Fatigue Design

22

HDPE Fatigue Design Fatigue surge pressure analysis in AWWA M55

Fatigue life method is not in current AWWA M55 (typically, not a limiting factor)

Fatigue life method will be implemented in revised AWWA M55

PE 3608 / PE 4710 design fatigue life can be determined using fatigue curves provided in Marshall, G.P., Brogden, S: Final report of Pipeline Innovation Contract to UKWIR, 1997.

23

HDPE Fatigue DesignPPI-PACE methodology implemented from:• AWWA M55-2005, “PE Pipe – Design and Installation”• Jana Lab, 2012, “Fatigue of Plastic Water Pipe: A

Technical Review with Recommendations for PE4710 Pipe Design Fatigue”

PE4710 fatigue S-N curves data from: • Resistance of PE4710 Piping to Pressure Surge Events

in Force Main Applications, PP XVI, Barcelona, 2012

• UK Water Industry IGN 4-37-02 “Design Against Surge and Fatigue Conditions for Thermoplastic Pipes”

24

Test Specimens Cycles at 1.5 x PC(Recurring Surge)

Status

Straight Pipe11,213,023

NoFailures

10,038,073

6,754,833

Pipe with butt-fused joint

10,952,363

11,017,153Tests conducted by Jana Labs See Crabtree et al., PPXVI, 2012

After completion pipes cycled from 0 to 2 x PC for 2739 to 6665 cycles no failures – Shows lots of life remaining

PE4710 Recurring Surge Pipe Tests( cycles 0 to 1.5 x PC)

25

Jana 4 testsat 1500 psi

G.P. Marshall, S. Brogden, M.A. Shepherd (1998) “Evaluation of the Surge and Fatigue Resistance of PVC and PE Pipeline Materials for use in the U.K. Water Industry”, 

Plastics Pipe X, Goteburg, Sweden

Stress for PE4710 at 1.5 x PC = 1500 psi (10.34 MPa)

1450 psi

Number of Cycles to Failure

1st Generation PE

4th Generation PE

26

http://ppipace.com/

27

PPI-PACE: Purpose

1. Develop  a user friendly, free & online pipe software

2. Provide prelim. calculations for operating pressure, surge pressure and fatigue design life. 

3. Assist designers and owners in the evaluation of plastic pipe for water distribution, transmission and forcemains

4. Implement existing standards and methods: AWWA C900/C901/C905/C906,M55 and ASTM F714/D2241. 

28

PPI-PACE Defaults

Default Allowable RangeRecurring Surge Velocity

5 fps 4 – 8 fps

Occasional Surge velocity

8 fps 5 - 15 fps

Working Pressure

70 psi 40 psi (min.)

Anticipated Surges per day

55 cycles

Temperature 57 oF 40-100 oFMin. Design Life 100 years 50 (min.)

29

UNI-BELL and PPI-PACE

30

Design Example

18 inch DIPS/CIOD 160 psi Operating Pressures 4.0 fps Recurring Flow Velocity 7 fps Occasional Flow Velocity 57oF Temperature 100 Year Design Life 55 cycles/day = approx. 2 million cycles/100 yrs

31

Uni-Bell Design Example

1. Why HDPE DR 7.3? DR 13.5 (PC 160) is OK

32

33

34

35

• PE 4710 DR 13.5 (PC 160) OK

• PE 3608 DR 13.5 (PC 128) NG

• PVC DR 14 (PC 305) NG

36

• PE 4710 DR 13.5 (PC 160) OK• PE 3608 DR 13.5 (PC 128) NG

• PVC DR 14 (PC 305) NG

37

38

Summary• HDPE and PVC are both good materials

• According to existing approved design standards HDPE has much fatigue life than PVC

• PPI-PACE provides a simple, easy to use plastic pipe design tool that follows existing design standard methodologies

39