Condition Assessment of Large Diameter Mains

Transcription

1 Condition Assessment of Large Diameter Mains Bethany McDonald Northern California Pipe Users Group December 14, 2010 Solutions for Sustainable Infrastructure

2 Outline Pipe materials PCCP Metallic Leak detection in large mains PCCP assessment Focus on PipeDiver Condition assessment of metallic mains

3 Prestressed Concrete Cylinder Pipe Cross Section Mortar Steel Wires Concrete Core Steel Cylinder

4 The Problem - Corrosion

5 Failure Modes of Metallic Mains Blow-out A Longitudinal Cracking Circumferential Crack C D Blow-out Wall Corrosion Split Bell B Leadite Joint Seal

6 Multiple Cause Failure Need a broad tool box to identify various warning signs Bell Splitting Longitudinal crack Wall Corrosion

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8 Leak Detection in Large Mains

9 Leak Detection Credentials Over 12 years of experience including successful PPIC program ~2,900 leaks identified to date representing estimated 142 MGD in water saving Significant field experience with over 360 inspection projects completed In house decision support service capability Specialize in large diameter pipelines >12 Experience with multiple pipe materials

10 Why Look for Leaks? Knowledge about condition of pipeline Minimize risk Optimize repair & replace programs Reduction of emergency response costs Water production cost savings physical treatment and distribution Environmental sustainability conservation of a natural resource

11 Summary of Inspection Data Region Miles Inspected # Leaks Leaks/ mile Worldwide 2,009 2, North America Europe 991 2, Asia Pacific Africa & Middle East Material Miles Inspected # Leaks Leaks/ mile Concrete Cast Iron 708 1, Ductile Iron Steel Fiberglass

12 These are High Value Leaks Typically have a volume loss 20 times greater than small diameter mains Estimated to leak for an average of 10 years prior to surfacing AWWARF concludes average cost of a distribution main break is $5,000 to $10,000. The typical cost of a large diameter main rupture is $500,000 Large diameter main ruptures have significantly more impact on the community and environment

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14 Leak Detection Methods

15 Internal Leak Detection Options SmartBall Long point-to-point transmission pipelines Minimal laterals Sahara Complex interconnecting networks Urban centers The noise of flowing water in a large diameter pipe masks the sound of small/medium sized leaks making them harder to find with external tools Internal tools pass right over the leak

16 SmartBall Description Power Supply On-Board Memory Microprocessor Pinger Temperature Sensor Acoustic Sensor Rotation Sensor The protective foam ball cancels apparatus noises & provides a slightly negative floatability with direct water absorption Aluminum core contains data acquisition system Data is logged on a 4 GB, security digital card

17 SmartBall Inspection Process Retrieval Tracking Airdrie approach and departure from MH# Insertion Distance (m) Vel = 0.33 m/s Vel = 0.33 m/s Run time (min)

18 SmartBall Inspection Process

19 Sahara Description Surface Technology first introduced in 1995 by WRC in London. Significant experience gained in urban environments Tethered cable provides high degree of operator control Inspection results are provided in real time Platform technology offers leak & gas pocket detection, video inspection, wall thickness

20 Sahara Equipment Overview Electronics Stack Cable Drum Insertion Tube Cable Winch Sensor and Parachute Tracking Device

21 Project Deliverables Surface locations during/post survey Summary table in report Survey map in report, and GIS file with GPS data

22 Philadelphia, PA Pilot project using tethered inline leak location started in 2007 Included two leaks on 48 lines deep underground, crossing underneath a major highway. These leaks could not be located with traditional leak location equipment. One large leak turned into a break the day before it was scheduled for repair. Unfortunate, but confirms that leaks precede breaks Distance Surveyed 19.5 miles Leaks Located 47 leaks Average Size TBD50,000 gallons per day Leak Frequency 2.4 leaks / mile

23 More Applications In line Video Inspection Odessa, TX Inspection of a 14 PCCP line Line remained in service Tuberculation build up discovered and joints inspected Sewer Force Main Inspection Grand Forks, ND Inspection of 30 and 36 PCCP and PVC lines over 8 miles Two day inspection 10.5 hrs Two leaks and six air pockets identified

24 PCCP Assessment

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26 PCCP Assessment Methods Visual & Sounding Electromagnetics Acoustic Fiber Optics

27 Electromagnetic Inspections P Wave and RFTC Detects and quantifies wire break damage Provides estimate of wire breaks in each pipe section Provides location of wire breaks

28 Typical Inspection Results

29 External Verification Pipe 105

30 Engineering Evaluation Determine repair needs How many wire breaks is too many? Perform risk evaluation Rehabilitation

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33 Validation: Pipe 32

34 Validation: Pipe 6

35 Large Diameter Long Distance Live Inspection TANK 37 km TANK

36 PipeDiver Launch

37 Retrieval

38 Condition Assessment of Metallic Mains

39 Condition Assessment of Metallic Mains Leak Detection Sahara SmartBall Average Wall Thickness Using Sahara and SmartBall Platforms Pipe Wall Defects and Anomalies Using the PipeDiver Platform

40 PWA Average Wall Stiffness/Thickness Relies on the measurement of acoustic pulses as they propagate along the pipe Propagation velocity of an acoustic pulse is directly proportional to the stiffness of the medium that it travels through Higher propagation velocity indicates higher wall stiffness Stiffness of the pipe wall reflects the condition of the pipe

41 SmartBall PWA Acoustic pulses are induced into the pipe A receiver records the acoustic pulses as they propagate along the pipeline 3 inch interval (0.25s) Acoustic Pulsers SmartBall

42 SmartBall PWA Results Relative Stiffness vs. Distance v.s. Distance from Insertion From Location Insertion Location 2 Anomaly Joints Anomaly Relative Stiffness Relative Stiffness Distance from Insertion Location [m] Distance From Insertion Location [m]

43 Remote Field Eddy Current (RFEC) Emitter sends signal into pipe wall Signal travels through pipe wall Detector receives signals Defects appear twice: once as each of emitter and detector pass by

44 Identification of corrosion pits Corrosion Pit Dual detection as exciter & detector pass pit

45 Results: Leak Detection & Acoustic Wall Thickness Testing Legend: Negligible Wall Thickness Loss Light Wall Thickness Loss Moderate Wall Thickness Loss Heavy Wall Thickness Loss Nominal pipe Pipe data N/A Small leak pinpointed Large leak pinpointed Upstream direction, distance in meters

46 Thank you Solutions for Sustainable Infrastructure

47 Corrosion Blow-Out Warning signs Outer coating damaged or lost External corrosion pitting Pinhole leaks in barrel Heavy corrosion throughout pipe wall Bedding loss from long term leakage

48 Joint Failure (Bell Splitting) Warning signs Use of Leadite joint sealer Cracks at bell end Leaking joints Longitudinal cracks Bedding loss from long term leakage

49 Cracking Failure Warning signs Hairline cracks in pipe Circumferential (mostly small diameter) Longitudinal (mostly large diameter) Spiral (mostly medium diameter) Pressure-dependent leaks Severe, visible cracking Bedding loss from long term leakage

50 SmartBall Performance Leak location accuracy (within 3 feet) Highly sensitive to leak noise (0.25 gpm) Operates in all kinds of pressure pipes (DI, Steel, GRP, PVC...) Applicable to diameter 12 and above Inspects up to 9 miles per day from a single deployment Operates through 4 valve openings Complies with usual water quality standards

51 Sahara Specifications Insertion: 2 tap (1 7/8 opening) Diameters: 12 and up (4 to 10 in special cases) Pressures: 5 to 200 psi Flow Rates: 2 to 12 ft/s (1 ft/s for very short distances) Distances: ½ mile (6,000 ft in ideal conditions) Bends: 135 total bends (270 for very short distances) Line Valves: Cannot survey past inline butterfly valves Laterals: Should be closed as sensor passes by, but sensor can generally be withdrawn if it goes down one

52 Information Obtained Exact leak position Approximate leak size Direction of main Depth of main (SmartBall) Location of main Spectrogram Power Cure

53 Spartanburg Water System, SC 15,000 ft 14 Cast Iron Pipe High risk line Two leaks were found, one small and one medium sized. The larger one had already eroded away a void 7 x 5 x 3 deep under this pipe in a main thoroughfare that carries heavy traffic. Bobby Walden Ops/Maint Mgr: It was remarkably accurate, within inches Rebecca West Tech Srvcs Mgr savings of $2 to $4MM by not having to replace a critical line

54 GIS Pipe Mapping Web based interface Visual consequence of failure and risk management Accurate asset monitoring for repair and replace programs Data inputs: manual inspections, electromagnetic inspections, leak identification, fiber optic monitoring

55 Visual & Sounding Internal inspection Distance measurements and pipeline features recorded Immediate identification of pipes in a state of incipient failure

56 RFTC Data AMPLITUDE PHASE

57 Data Analysis Distress Man Hole

58 Fingerprint + = DISTANCE NO DISTANCE

59 Interpreting the Signal CYLINDER VARIATIONS MIDDLE BREAKS NO BREAKS JOINT DISCONTINUITY END BREAKS

60 Quantification - Measurement DISTRESS LOCATION SIGNAL LENGTH BASELINE

61 Distressed pipe signal No breaks signal used to establish a baseline Superimpose the 2 signals when making the measurement

62 Factors Affecting RFEC/TC Signal Wire Anchoring Variation in Wire Spacing Diameter Variations Wire Sp lice Joint Configuration Material Properties Thickness Variations Sho rting Stra p s Installation

63 Acoustic Monitoring Recorded Wire Break

64 Data Acquisition Unit Acquires acoustic data Filters noise Transmits wire break information Unfiltered Filtered

65 VALUE ADDED SERVICES Acoustic fiber optic (AFO) monitoring Wire break notifications

66 SAMPLE WIRE BREAK NOTIFICATION

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69 Pipeline Selection: SmartBall Most efficient for use on long mains Frequent laterals with unknown locations bring some risk Long cross country mains: SmartBall s Sweet Spot More complex network = increasing risk SmartBall Maximum Value Longer pipeline length = increasing ease of use

70 Pipeline Selection: Sahara Long cross country mains may lack existing taps Small diameter mains often have too many bends Urban transmission mains: Sahara s Sweet Spot More complex network = decreasing ease of use Sahara Maximum Value SmartBall Maximum Value Longer pipeline length = increasing ease of use

71 Pipeline Selection: External Tools When more sensitive inline tools are not feasible Hydrant access on small mains offers improved sensitivity Can be used to fill in gaps between inline inspections More complex network = increasing sensitivity External Tool Maximum Value Sahara Maximum Value SmartBall Maximum Value Larger pipeline diameter = decreasing sensitivity