Diagnostic Method on Cast Iron Pipes JWRC

Transcription

1 Diagnostic Method on Cast Iron Pipes JWRC Japan Water Research Center

2 1.Introduction

3 Proportion to total length of pipes for water supply ( ) DIP CIP SP ACP VP Others % 12% 3% 18% 28% 3% % 32% 5% 3% 3% 3% DIP 306,324km CIP 26,648km ACP 18,692km SP 16,324km Others VP 183,486km 568,210 km(2003) 3

4 Study Results of Pipeline Engineering Department (1989~) Epoch Project (2002~2004) SP The diagnostic, rehabilitation and replacement manual on steel pipes VP The diagnostic, rehabilitation and replacement manual on PVC pipes CIP The diagnostic, rehabilitation and replacement manual on cast iron pipes ACP The diagnostic manual on asbestos cement pipes

5 2.Diagnostic Method on Cast Iron Pipes for Water Distribution Network

6 The History of Cast Iron Pipes in Japan 1885 CIPs were first introduced in Yokohama City CIPs were started to spread DIPs were produced CIPs have discontinued. It has been more than 40 years since CIPs were installed and they are aging. 6

7 Photomicrograph of Cast Iron Cast Iron Pipe Production Period 1890~1940 Tensile Strength 12.5kgf/mm 2 ( 123 N/mm 2 ) High Quality Cast Iron Pipe Production Period 1930~1970 Tensile Strength 25.0kgf/mm 2 ( 245 N/mm 2 ) Ductile Iron Pipe Production Period about 1954 ~ Tensile Strength 420 N/mm 2 Elongation 10% 7

8 Required functions for pipelines 1) Sufficient water quantity and pressure 2) Maintaining water quality 3) Effective utilization of water resources 4) Securing water for fire fighting 5) As an essential service in case of disaster It is important to perform these functions appropriately. 8

9 Damage by Hyogo-ken Nambu Earthquake (1995) 9

10 Damage by Hyogo-ken Nambu Earthquake (1995) 10

11 Hyogo-ken Nambu Earthquake ~ Damage of Cast Iron Pipes~ 1) 11

12 Hyogo-ken Nambu Earthquake ~ Damage of Cast Iron Pipes~ 2) 12

13 Function of pipeline and its deterioration Function of pipeline Deterioration of aged pipes Due to Changes of Installation Environments Trouble Level of Required Function Year 13

14 Vertical crack Crease Damage of Cast Iron Pipe 14

15 Tuberculation in Pipe 15

16 Accident rate (number/km/year) Cast Iron Pipe Ductile Pipe average Fiscal year Accident rate (Tokyo) 16

17 Target setup Standard diagnosis Prioritized plan Importance of the pipelines Financial situation Restrictions on construction No Necessity for detailed diagnosis Yes Detailed diagnosis Comprehensive evaluation Renewal and regeneration plans The procedure of diagnosis and evaluation 17

18 1) The Standard Diagnosis

19 Information obtained by daily maintenance Maintenance works Information Maintenance Operation Inspection Preparation Water volume management Water quality management Point of pipeline, Pipe size Laying date, Standard Accident rate Leakage Volume Distributions of Water pressure Location and time of occurrence of red water 19

20 Extraction of cast iron pipes An example of mapping system 20

21 Pipes Laying environment Accident s records Measured records Information of Cast Iron Pipeline Classifications Pipe size Type of joint Mortar lining (in pipe) Laying date Laying depth Surface load Water pressure Property of soil Erosiveness of soil N-value Possibility of liquefaction Existence of irregular sinking Complaint rate on water quality Water Leakage records Damaged pipeline records Water passage, Pressure, Quality, etc. Date, Standard Contents Lange, Medium, Small Sand, Silt, Clay, Others Evaluation standard of soil (ANSI) Date of boring, FL-value Settlement, Possibility of sinking Complaint records ( e.g. red water, poor water flow) 21

22 The standard diagnosis Diagnosis item Agreement rate (Measured value / Target value) Complaint rate (number/km/year) Accident rate (number/km/year) Leakage volume Damaged rate by earthquake (number/km) Contents Water pressure Water quality Poor water flow Red water Water leakage Damaged pipes Leakage Volume Earthquake-proof 22

23 Flow of diagnosis method for Cast Iron Pipes Report of the Cast Iron Pipeline Item of diagnosis Evaluation <Classification> <Item> (Aging Degree) Pipes Laying environment Obstruction record Measurement record Pipe size Coating method Laying date Laying depth Type of pipe Surface load Water pressure Property of soil Possibility of liquefaction Complaint to water quality Water Leakage record Water pressure Water quality Assumption of damage by earthquake Complaint rate (Poor water flow, Red water etc ) Accident history Leakage Volume Agreement rate Comprehensive evaluation 23

24 Aging level based on accident rates of Cast Iron Pipelines Aging Level Accident rate :a (number/km/year) Evaluation (Possibility of accident) Ⅰ a 2.8 High Ⅱ 2.8 >a 1.4 Middle Ⅲ 1.4 >a > 0 Low Ⅳ a = 0 None 24

25 Score table by Cast Iron Pipeline s condition Items Conditions Points Pipe size (mm) Mortar lining (in pipe) Laying date Laying depth (m) Surface load Water pressure (kgf/cm 2 ) Property of soil ~ ~ ~ ~ ~ ~ w/ large vehicles w/o large vehicles ~5.0 0~2.0 Gravel Others

26 2) The Detailed Diagnosis

27 Detailed Investigation Physical method Analytic method The future estimate Continuous detailed investigation Statistical diagnosis method Appraise State of malfunction State of malfunction and influence over the time Measures against malfunction The Detailed Diagnosis 27

28 Example of Physical method Investigation targets Inner pipe wall Rust Lining Corrosion of outer pipe Remaining thickness Investigation method Non-open cut Nonsuspension water Suspension cut Endoscope Inner pipe investigation robot Investigation of inner pipe operation Measurement using γ- ray Measurement using ultrasound Open cut Nonsuspension water Suspension cut Investigation corrosion of outer pipe operation Investigation of dug out pipes :Effective method :Reference method 28

29 Insert an endoscope from hydrant and observe inside the pipe 29

30 Insert an investigation robot from hydrant and examine 30

31 Head Water source Consideration (Pipe size) Solve the poor water flow An example of analytic methods (Water pressure distribution) 31

32 Area where concentration of residual chlorine is low Concentration 残留塩素濃度 of residual Chlorine 0.6 ~ 0.9 mg/l 0.3 ~ 0.6 mg/l 0 ~ 0.3 mg/l Candidate pipeline for improvement (Bold line) Area where concentration of residual chlorine is high Water source An example of analytic methods (Water quality analysis) 32

33 Detailed Investigation Physical method Analytic method The future estimate Continuous detailed investigation Statistical diagnosis method Appraise State of malfunction State of malfunction and influence over the time Measures against malfunction The Detailed Diagnosis 33

34 The Function of pipeline Diagnosis (accumulation of data) The future estimate Present Future Time The future estimate 34

35 Detailed Investigation Physical method Analytic method The future estimate Continuous detailed investigation Statistical diagnosis method Appraise State of malfunction State of malfunction and influence over the time Measures of malfunction The Detailed Diagnosis 35

36 1Water pressure and quality Disagreement rate High 2Leakage rate High 3Complaint rate High Aging degree Low 4Damage rate by earthquake High Aging degree High 5Accident rate High 2 Low 1 Low 3 Low 4 Low 5 Low Evaluation image of aging function 36

37 Standard diagnosis Importance of the pipelines Financial situation Diagnosis of aging pipes comprehensive evaluation Renewal and regeneration plans Detailed diagnosis Prioritized plan Restrictions on construction Comprehensive evaluation 37

38 Thank you for your attention.