Exploring the Direct Relationship Between Transients and Wire Breaks. February 9 2pm EST

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1 Exploring the Direct Relationship Between Transients and Wire Breaks February 9 2pm EST

2 Do you have PCCP lines? Poll Question

3 Poll Question Do you have a budget to repair or replace or do condition assessment of your transmission line (in the next 2 years)?

4 Reduction of Failure Risk of Prestressed Concrete Cylinder Pipe (PCCP) by Reduction in Maximum Pressure Rasko Ojdrovic Simpson Gumpertz & Heger Webinar Direct Relationship Between Transients and Wire Breaks 9 February

Simpson Gumpertz & Heger PCCP Pipeline Experience More than 25 years of research, analysis, design, condition assessment, failure investigation and repair of all kinds of pipelines Developed AWWA

5 Simpson Gumpertz & Heger PCCP Pipeline Experience More than 25 years of research, analysis, design, condition assessment, failure investigation and repair of all kinds of pipelines Developed AWWA C304 standard for design of PCCP Developed AWWA C305 standard for CFRP repair design of PCCP Developed thrust restraint design procedure in AWWA M9 Manual Developed procedure for risk assessment of PCCP with broken wires Developed Best Practices Manual for WRF Developed concrete pipeline risk ranking for EPRI 100 s of projects for pipe investigation, condition assessment, failure risk analysis, repair prioritization and repair

6 Prestressed Concrete Cylinder Pipe (PCCP) Embedded Cylinder Pipe (ECP) and Lined Cylinder Pipe (LCP)

7 PCCP Failure Risk Reduction This presentation will discuss failure risk reduction of PCCP lines by reduction of maximum transient pressures. Background on PCCP Structural Analysis of PCCP Failure risk analysis (fitness-for-service) Repair prioritization and repair options

8 Value PCCP lines can last a design life with high reliability if properly designed for loads and environment, manufactured, installed and operated One prevented pipe failure saves $$$$$$$ Rupture repair cost Business interruption Loss of production and revenue Collateral damages Environmental pollution Litigation Proactive preventive maintenance of pipelines extends the life of these major assets

9 Risk of Pipe Failure Likelihood of pipe failure depends on: Design adequacy (hoop and longitudainal effects) Manufactured quality of pipe and constitutive materials (Class IV wire, mortar coating, concrete core, etc.) Transportation and handling (damage) Installation (damage, poor bedding, etc.) Corrosivity of environment (Chlorides, ph, etc.) Third party damage Operation loads higher than design loads (soil cover height, live load, transient pressures) Higher than design pressures may cause cracking of mortar coating and other damage that may affect pipe durability, need for repair, and failure.

10 Solution Perform Failure Risk Analysis to determine benefits of pressure reduction Reduce maximum transient pressure Strength with contribution of soil RP1 RP3 Strength without contribution of soil + Serviceability RP4 Damage RP2 Length of Distress

Longitudinal cracks in inner core Hollow sounding inner

11 PCCP Distress Signs Coating cracks and delaminations Corrosion of prestressing wires Broken prestressing wires Longitudinal cracks in inner core Hollow sounding inner core Corrosion of steel cylinder Leak (through joints or steel cylinder)

12 Mortar Coating Petrographic analysis of polished and thin sections, SEM Chloride ion concentration in the coating Unit weight, absorption and porosity Cracking significantly reduces protection provided by mortar coating

13 Prestressing Wire Breakage Corrosion Embrittlement

14 Corrosive Environment Chlorides Sulfates Acids Carbonation Stray currents Coating cracking exposes wires to corrosive environment

15 Installation and Damage

16 Structural Analysis of PCCP AWWA C304 Standard Limit state design procedure Validation testing of PCCP State of stress of PCCP accounting for creep, shrinkage and wire relaxation UDP program used for analysis and design of PCCP since 1992

17 Structural Analysis of PCCP Combined Loads Limit State Curves for Class 100 psi Pipe Core Microcracking Coating Microcracking Cylinder Yield Earth Load (lb/ft) Wire fsg Wire yield 0.75 f'c Envelope We Pressure (psi) Core Cracking Coating Cracking Pw Pw + Pt

18 Limit State Curves for Class 75 psi Pipe Core Microcracking Coating Microcracking Cylinder Yield Earth Load (lb/ft) We Pipe Rupture Wire fsg Wire yield 0.75 f'c Envelope Core Cracking Pressure (psi) Coating Cracking Pw Pw + Pt

19 Mortar Coating Cracking from High Transient Pressures

20 Hydraulic Transient Analysis Calculate maximum working and working plus transient pressure Essential for determining risk of pipe failure Measure pressures to verify analysis

21 PCCP Asset Management - Failure Risk Analysis Approximately 3.7% of pipes have broken wires, and vast majority can continue to provide reliable service over time Typically, a fraction of pipes with broken wires need to be repaired within 5 years How to prioritize pipe repairs? Use Failure Risk Analysis to determine margin to failure, benefits of reduction in transient pressures, and to prioritize pipe repairs: Repair immediately, Repair within 5 years (or by next available outage), and No need for repair; monitor periodically

Failure Risk Analysis Developed by SGH in early 2000 s and

Non-linear and linear finite-element models of the failure of

condition near broken wire zones Model of pipe failure

22 Failure Risk Analysis Developed by SGH in early 2000 s and based on: Hydrostatic pressure tests of pipe with broken wires Non-linear and linear finite-element models of the failure of PCCP Field inspection of distressed pipe to characterize pipe condition near broken wire zones Model of pipe failure incorporating the results of all studies Risk curves technology (US Patent )

23 Failure Risk Curves Consider three limit states on internal pressure: Serviceability Limit State onset of visible cracking of concrete core Damage Limit State core structural cracking and increase in wire stress adjacent to BWZ Strength Limit State pipe failure

24 Risk Curves - Repair Priority 1 RP3 + Serviceability RP4 Strength with contribution of soil Strength without contribution of soil Damage RP1 RP2 Repair Priority 1: Exceeds strength limit state Indicates imminent rupture Pipe should be repaired as soon as possible

25 Risk Curves - Repair Priority 2 Strength with contribution of soil RP1 Repair Priority 2: RP3 + Serviceability RP4 Strength without contribution of soil Damage RP2 Exceeds the damage limit state Failure occurs with time Pipe should be repaired soon

26 Risk Curves - Repair Priority 3 RP3 Strength with contribution of soil RP1 Strength without contribution of soil Repair Priority 3: Exceeds the serviceability limit state Failure occurs after a much longer time No repair required Inspect periodically Serviceability RP4 Damage RP2

1B 90 Serviceability 60 1C 30 4B 3B 2B 0 0 20 40 60 80 100 120 140 160

Damage limit state Strength limit state without soil resistance Strength

27 Verification of Risk Curves in. ECP 270 Strength Damage 1A Pressure (psi) A 3A 2A 1B 90 Serviceability 60 1C 30 4B 3B 2B Number of Broken Wires Servic eability lim it state Damage limit state Strength limit state without soil resistance Strength limit state with soil resistance Cylinder ultim ate strength Cylinder yield strength Pipe No. 5BH Failed Pipe

28 Verification of Risk Curves 48 in. LCP

29 Failure Risk Reduction Transient Pressure RP3 Strength with contribution of soil Strength without contribution of soil RP1 Reduction in pressure reduces failure risk as it increases the tolerable length of prestress loss Serviceability + RP4 Damage RP2 Pipe may leak before rupture

30 Summary PCCP and other lines can be damaged by high transient pressures Perform hydraulic transient analysis and transient pressure monitoring to determine magnitude of the problem Perform failure risk analysis to determine the benefits of reduction in maximum transient pressures and failure risk of pipe Modify system for surge protection and pipeline operation as needed Identify distressed pipes, evaluate their risk of failure at maximum pressure, and determine repair priority Repair pipes with unacceptable failure risk to maintain acceptable pipeline reliability at least cost

31 Repair and Rehabilitation Options Repair distressed pipe so that the repair pipe would have the desired strength, durability, reliability, and hydraulic performance Evaluate repair options including External Post-tensioning Pipe replacement with closure piece Replacement of a portion of the pipeline Concrete encasement External FRP repair Internal CFRP hand lay-up repair Steel or FRP liner HDPE slip-lining repair

32 Questions? Rasko Ojdrovic Questions? Simpson Gumpertz & Heger

33 Poll Question Do you currently monitor pressure transients on your transmissions mains?

34 Transients Are they real? And so what? Cliff Jones, SVP Syrinix Inc

35 Syrinix Inc Subsidiary of UK Company North American offices with strong client base

36 Agenda The impact of transients Why you need high sample data to detect transients How you can detect them and locate the cause The benefits of smart monitoring

37 Pressure Transients in Networks So What? There is a direct relationship between pressure and burst and leakage rates. Eliminate pressure surges to reduce breaks and leakage. Reduce pressure to reduce leakage.

38 What About Transmission Mains? The issue is not necessarily leakage, but whether transients increase the risk of catastrophic failure

39 What Effects do Transients Have? The Proper opening and closing of valves is fundamental to safe pipeline operation An example: 800 ft long pipeline, water flowing at 4 ft per second The pressure in the line at the downstream valve is 60psi If the valve is closed over a 10 second period, the pressure increases to 82psi, i.e. water hammer increased pressure by 22 psi Pf = ((0.070VL)/t)+Pi Pf = Pressure resulting from transient (water hammer) V = Change of velocity of liquid L = upstream pipe length t = Valve closing time Pi = inlet pressure (before transient) (Source: Baker Corp white paper, May 2016)

What if the Same Valve is Changed in 1 Second? Pf = ((0.070VL)/t)+Pi Pf = Pressure resulting from transient (water hammer) V = 4 ft/second L = 800 ft t = 1 sec Pi = 60 psi Pf = ((0.

40 What if the Same Valve is Changed in 1 Second? Pf = ((0.070VL)/t)+Pi Pf = Pressure resulting from transient (water hammer) V = 4 ft/second L = 800 ft t = 1 sec Pi = 60 psi Pf = ((0.070*4*800)/1)+60 Pf = 284 psi Water hammer increases the pressure by 224psi NB: If flow rate is higher the transient is greater.. If HDPE DR17 pipe rated at 100 psi was used, it would operate within specifications under normal conditions. If you had the transient situation failure would result

41 What Causes Transients/Water Hammer/Surges? The impact of transients includes: Worst Case: destroys pipelines, tunnels, valves, pumps, and potential for loss of life Less Severe: crack internal lining, damage connections and flanges between pipe sections, cause deformations to equipment such as valves, air valves, and surge protection devices. Transients will Cause wire breaks on PCCP

42 Do Transients Cause Wire Breaks? We have seen that a rise in pressure can increase the risk of failure (SGH). Pure Technologieshave done work comparing pressure transients to wire break activity; a lot of this study was conducted on WSSC pipelines. Paper presented at AWWA Infrastructure Conference in Phoenix, November Transient Pressure Monitoring: Real World Applications by Brian Gresehover and Travis Wagner. Compared incidences of wire breaks with transient events. Other anecdotal examples of transients or pressure surges causing wire breaks and PCCP failures: something has to cause the pipe to suddenly fail

43 The PURE Technologies Study Detected recurring transient event with negative pressures to -9 psi, at frequency of 6 pump cycles / hour. New ARV installed and amplitude of recurring pressure cycle reduced significantly. Resulted in an estimated change in expected useful life, based on structural fatigue of 30 years to 118 years (note other factors that are typically considered in design life would reduce this estimation further).

44 Reference: Pure Technologies. AWWA Infrastructure Conference, Phoenix 2016 Transient Pressure Monitoring: Real World Applications Case Study at WSSC

45 Poll Question Have you seen PCCP failures caused by transients or pressure surges?

46 How Do you Detect Transients? Transient Pressure Monitoring System Traditional loggers will not detect transients Must have a High sample rate 128x per second Sample rates of 1 s/s, 16 s/s or 32 s/s are inadequate

47 Collecting data at 32s/s means you miss damaging transients and have a distorted, optimistic view of pipe behaviour

48 How do you detect Transients? Transient Pressure Monitoring System Traditional loggers will not detect transients Must have a High Sample Rate 128x per second Must always be on at that rate no accelerating only once transient detected Must have real time event notification Units must be synchronised to support transient tracking Must be battery operated with up to 5 years at the high sample rate Must be Waterproof/ Rugged/ Field ready Must work on all pipe sizes Needs to be easy to install Must have easy communications not drive by

notification Units synchronised to support transient tracking Lithium Battery operated with up to 5 years at

49 PIPEMINDER-S Transient Pressure Monitoring System Monitors pressure and transients on a pipe or network High sample rate 128x per second Is always on not simply accelerating once transient is detected Real-Time event notification Units synchronised to support transient tracking Lithium Battery operated with up to 5 years at high sample rate Waterproof/ rugged/ field ready Works on all pipe sizes Is easy to install Built in 3G SIM card

50 Deployment

51 Standard Pressure Monitoring System designed for pressure variances of 100 psi IMAGE WITH BORDER

52 High Frequency Pressure Monitoring System designed for pressure variances of 100 psi

53 This is what Standard Pressure Monitoring Misses! 327 psi change in.008 seconds

54 Data Resulted in Improved Operations Corrections made to PLC programming

55 Case Study Monitoring systems installed at 3 locations identified as: - Site A - Site B - Site C Different pipelines Several miles apart Site A Site B Site C

56 Transients Source and Impact

57 Ability to Time Stamp Events

59 Time elapsed from start of event: 8.42 min 40 psi pressure range

60 Another example of how transients travel round a system: This client has 75 miles of transmission main (PCCP and DI) 10 monitoring units deployed Transients can be tracked around the entire system Emergency pump shut down

61 Pump start up: 15 min sample data

62 Add High Sample Monitoring Data:

63 Drill down into the Data:

64 Second Transient Lasted seconds:

65 Assessing Risk on Several Transmission Mains:

66 Adding High Sample Data:

67 Pressure Drop Lasted Seconds:

68 Making the Best Use of the Data Time stamp the transients Overlay data onto GIS map Triangulate back to identify the cause of the transient Take proactive action to avoid transients in future Identify the location of bursts on river crossings or remote pipelines Justify the replacement of valves

69 Network Calming Works Graph explains why replacing valve was justified:

Benefits of transient monitoring and network calming: Reduce Risk of Failure Increased asset life Reduce capital costs Reduce O&M costs Reduce Non revenue water Reduce Break/leak

70 Benefits of transient monitoring and network calming: Reduce Risk of Failure Increased asset life Reduce capital costs Reduce O&M costs Reduce Non revenue water Reduce Break/leak frequency Improved Water Quality Increased network knowledge provides current, relevant information to actively assist in making better strategic decisions. Immediate and future cost saving.

71 Conclusions Transients They do occur on your systems You can detect them with high sample monitoring If you know they are there and what is causing them, you can do something about it.. Reducing or Removing Transients Reduces leakage and breaks Reduces the risk of wire breaks in PCCP Extends life of your infrastructure Reduces operational costs Reduces water loss Allows you to focus resources elsewhere

72 Smart Systems Are cost efficient Provide useful information Can be selective/ appropriate Can tell you what is going to break, before its too late Will bring to light where it s best to focus your time, energy and resources and most importantly, money

73 Introducing - PIPEMINDER-T Leak and Pressure Monitoring for Transmission Mains

74 PIPEMINDER-T Cost effective alternative to leak detection inspection Detects emerging leaks on large, critical transmission mains Continuous leak detection every day, all the time as well as continuously monitoring pressure transients Can monitor continuously for three years for same price as a single leak detection inspection Ideal for sections with difficult access Installed on PCCP, Steel, DI, CI lines Lines 12 to 99 Mexico, Atlanta, WaterOne, PG&E, EBMUD, Singapore. 100 s of systems installed within the UK (Thames Water)

75 Poll Question Would you now consider monitoring pressure transients on a transmissions main?

76 Questions? Cliff Jones Senior Vice President, Syrinix Inc E cliff.jones@syrinix.com M

VERIFICATION OF PCCP FAILURE MARGIN AND RISK CURVES

1413 VERIFICATION OF PCCP FAILURE MARGIN AND RISK CURVES Rasko P. Ojdrovic *, Peter D. Nardini, and Mehdi S. Zarghamee * Ph.D., P.E., M. ASCE, Principal, rpojdrovic@sgh.com, (781) 907-9231 P.E., A.M. ASCE,