Basic Measurements for Pipe Inspections

Transcription

1 Basic Measurements for Pipe Inspections Period 7 Basic Corrosion Course 2017 February 21-23, 2017 Mark Anderson-MTS 1

2 DOT External corrosion control: Examination of buried pipeline when exposed. Requires that the exposed surface of pipe must be examined for external corrosion February 21-23, 2017 Mark Anderson-MTS 2

3 Key for Success Consistent data gathering Type of information Measurement of conditions (good/fair/bad) Documentation A must for record keeping February 21-23, 2017 Mark Anderson-MTS 3

4 February 21-23, 2017 Mark Anderson-MTS 4

5 February 21-23, 2017 Mark Anderson-MTS 5

6 Stake the excavation site to maintain control of base measurements February 21-23, 2017 Mark Anderson-MTS 6

7 Photographic documentation Land use Foreign structures February 21-23, 2017 Mark Anderson-MTS 7

8 Photographic documentation February 21-23, 2017 Mark Anderson-MTS 8

9 GIS Geographic Information System Location Latitude / Longitude Northern / Easting Physical attributes Wall Thickness Grade of Pipe Coating Type System will improve with quality data February 21-23, 2017 Mark Anderson-MTS 9

10 GIS February 21-23, 2017 Mark Anderson-MTS 10

11 Soil Moisture February 21-23, 2017 Mark Anderson-MTS 11

12 Definitions of terms ph ph is a measure of how acidic or basic things are and is measured using a ph scale between 0 to 14 Acidic things having a ph between 0-7 Basic things having a ph from 7 to 14. For instance, lemon juice and battery acid are acidic and fall in the 0-7 range, whereas seawater and bleach are basic (also called "alkaline") and fall in the 7-14 ph range. Pure water is neutral, or 7 on the ph scale. February 21-23, 2017 Mark Anderson-MTS 12

13 Definitions of terms February 21-23, 2017 Mark Anderson-MTS 13

14 Equipment needed Soil ph High impendence meter capable of measuring DC volts. Copper / copper sulfate reference cell Antimony cell Method Insure Copper / copper sulfate reference cell is charged with copper sulfate and distilled water Check calibration of reference cell against a new cell should be with in 5 mv February 21-23, 2017 Mark Anderson-MTS 14

15 Soil ph (continued) Insure that the tip of the antimony cell is clean and shinny Connect reference cell to the negative terminal of meter Connect antimony cell to the positive terminal of meter Place tip of reference cell and antimony cell in the ground, making sure you have good contact Avoid roots and other organics Record reading IS READING REASONABLE? February 21-23, 2017 Mark Anderson-MTS 15

16 Soil ph (continued) Digging to avoid roots Cleaning tip of cell February 21-23, 2017 Mark Anderson-MTS 16

17 Soil ph (continued) Taking reading Converting mv to ph February 21-23, 2017 Mark Anderson-MTS 17

18 Definitions of terms Soil Resistivity Soil resistivity is an electric characteristic of the soil / ground water that affects the ability for currents to flow through the electrolyte (soil/groundwater) Resistivity is the inverse of conductivity February 21-23, 2017 Mark Anderson-MTS 18

19 Definitions of terms Soil Resistivity (continued) Soil resistivity ,000 1,000 2,000 2,000 10,000 Above 10,000 Degree of Corrosivity Very Corrosive Corrosive Moderately Corrosive Mildly Corrosive Negligible February 21-23, 2017 Mark Anderson-MTS 19

20 Soil Resistivity Collins Rod Equipment needed Collins rod with receiver Method Insure tip of rod is clean Connect leads from receiver to rod Drive rod into ground Connect ear phone Turn unit on February 21-23, 2017 Mark Anderson-MTS 20

21 Soil Resistivity Collins Rod (continued) Method Adjust dial from lowest reading until unit nulls Adjust dial from highest reading until unit nulls Make final reading IS READING REASONABLE? February 21-23, 2017 Mark Anderson-MTS 21

22 Soil Resistivity Collins Rod (continued) Ensure tip is clean Drive rod in ground February 21-23, 2017 Mark Anderson-MTS 22

23 Soil Resistivity Collins Rod (continued) Turn unit on Adjust dial to obtain reading February 21-23, 2017 Mark Anderson-MTS 23

24 Pipeline Outside Diameter Equipment needed Hammer, scraper and wire brush Flexible tape measurer Method Clean coating from pipe 360 deg. Measure around the pipe in inches Take measurement and dived by pi (3.142) Record If coating is not removed, measure coating thickness. Take answer and subtract twice the coating thickness IS READING REASONABLE? February 21-23, 2017 Mark Anderson-MTS 24

25 Pipeline Outside Diameter Clean and measure the pipe February 21-23, 2017 Mark Anderson-MTS 25

26 Pipeline Outside Diameter Record the measurement Calculate the outside diameter February 21-23, 2017 Mark Anderson-MTS 26

27 Definitions of terms O clock A measurement to identify the location of a area of concern on the pipe. The measurement is to document the location around the circumference of the pipe. February 21-23, 2017 Mark Anderson-MTS 27

28 Definitions of terms O clock (continued) 12:00 9:00 3:00 6:00 February 21-23, 2017 Mark Anderson-MTS 28

29 Definitions of terms O clock (continued) 3:00 3:00 February 21-23, 2017 Mark Anderson-MTS 29

30 Definitions of terms Pipe to Soil A measurement of the pipe potential versus a standard half-cell electrode The measurement is normally taken with a copper-copper sulfate reference cell A high impendence voltmeter is used with the reference cell to obtain a reading February 21-23, 2017 Mark Anderson-MTS 30

31 Definitions of terms Pipe to Soil (continued) Pipe to soil readings are normally more negative than 850 mv on pipeline with cathodic protection Unprotected steel will range from 400 mv to 800 mv February 21-23, 2017 Mark Anderson-MTS 31

32 Pipe to soil Equipment needed High impendence meter capable of measuring DC volts. Copper / copper sulfate reference cell Method Insure Copper / copper sulfate reference cell is charged with copper sulfate and distilled water Check calibration of reference cell against a new cell should be with in 5 mv February 21-23, 2017 Mark Anderson-MTS 32

33 Check for calibration February 21-23, 2017 Mark Anderson-MTS 33

34 Remove copper rod from reference cell February 21-23, 2017 Mark Anderson-MTS 34

35 Clean copper rod with sand paper February 21-23, 2017 Mark Anderson-MTS 35

36 Charge reference cell with new copper sulfate and distilled water February 21-23, 2017 Mark Anderson-MTS 36

37 Verify reading February 21-23, 2017 Mark Anderson-MTS 37

38 Pipe to soil (continued) Connect reference cell to the negative terminal of meter Connect the wire that will go to pipeline to the positive terminal of meter Place tip of reference cell in the ground, making sure you have good contact Connect the wire from the positive terminal of the meter to the pipe Record reading IS READING REASONABLE? February 21-23, 2017 Mark Anderson-MTS 38

39 Measurement of pipe-to-soil potentials At ground surface and at pipe interface Need to note location February 21-23, 2017 Mark Anderson-MTS 39

40 Pipe to Soil February 21-23, 2017 Mark Anderson-MTS 40

41 Pipe to Soil February 21-23, 2017 Mark Anderson-MTS 41

42 Coating type Shrink Sleeve and FBE February 21-23, 2017 Mark Anderson-MTS 42

43 Coating Thickness Equipment needed Wire brush Coating thickness gauge Method Clean surface of coating Place thickness gauge along longitudinal axis of the pipe Start with gauge at highest reading Push indicator of gauge in Rotate dial until indicator pops up Record If coating is thicker than range of gauge, not that coating thickness was greater than the limit (note limit) IS READING REASONABLE? February 21-23, 2017 Mark Anderson-MTS 43

44 Coating Thickness Place thickness gauge on clean pipe Turn dial until indicator pops up February 21-23, 2017 Mark Anderson-MTS 44

45 Mapping of coating degradation (blisters, disbondment, etc.) February 21-23, 2017 Mark Anderson-MTS 45

46 Measurements of under-film liquid ph February 21-23, 2017 Mark Anderson-MTS 46

47 Identification of corrosion defects February 21-23, 2017 Mark Anderson-MTS 47

48 Mapping and measurement of corrosion defects February 21-23, 2017 Mark Anderson-MTS 48

49 Simple Pit Equipment needed Hammer, scraper and wire brush Pit gauge Method Clean coating from pipe in the pit area Outline pit area Place pit gauge edge along longitudinal axis of the pipe Measure depth of pit Measure length of the pit along longitudinal axis of the pipe Record measurements IS READING REASONABLE? February 21-23, 2017 Mark Anderson-MTS 49

50 Simple Pit Clean pit and pipe Outline pit area February 21-23, 2017 Mark Anderson-MTS 50

51 Simple Pit Measure pit depth Measure pit length February 21-23, 2017 Mark Anderson-MTS 51

52 Complex Pit Equipment needed Hammer, scraper and wire brush Pit gauge Straight edge, ruler, wax pencil Method Clean coating from pipe in the pit area Outline pit area Grid pit Place pit gauge edge along longitudinal axis of the pipe Measure depth of pit in each grid (max pit depth for each grid) Record measurements IS READING REASONABLE? February 21-23, 2017 Mark Anderson-MTS 52

53 Complex Pit Clean pipe Outline pit February 21-23, 2017 Mark Anderson-MTS 53

54 Complex Pit Grid pit Measure and record February 21-23, 2017 Mark Anderson-MTS 54

55 Complex Pit Grid pit Measure and record February 21-23, 2017 Mark Anderson-MTS 55

56 Internal Corrosion Mapping Figure 2 -- Radiograph Setup (Cont.) NOTE: Do NOT Radiograph any girth weld. With "Shallow" Slope Change Due to Pipe Bend -- Inclusive Angle > 120 deg Single Film 6:00 FLOW End Point of Half Ponding Minimum of the Least of Half Ponding Point or 10'-0" Minimum of the Least of Projected End Point of Ponding End Point of Half Ponding February 21-23, 2017 Mark Anderson-MTS 56

57 Internal Corrosion Mapping February 21-23, 2017 Mark Anderson-MTS 57

58 Internal Corrosion Mapping February 21-23, 2017 Mark Anderson-MTS 58

59 Internal Corrosion Mapping February 21-23, 2017 Mark Anderson-MTS 59

60 Internal Corrosion Mapping February 21-23, 2017 Mark Anderson-MTS 60

61 Dent Equipment needed Hammer, scraper and wire brush Rigid straight edge Small ruler Method Clean coating from pipe in the dent area and down the pipe Place Rigid straight edge along longitudinal axis of the pipe Measure depth of dent at the deepest section Measure length of dent along longitudinal axis of the pipe Record measurements IS READING REASONABLE? February 21-23, 2017 Mark Anderson-MTS 61

62 Dent Clean pipe Measure depth of dent February 21-23, 2017 Mark Anderson-MTS 62

63 Definitions of terms (continued) MIC Microbiologically Induced Corrosion Caused by Sulfur Reducing Bacteria (SRB) Once a suspected area of MIC has been located, the presence of bacteria can be confirmed by means culture methods and antibody analyses or a field test using dilute hydrochloric acid. Detection of SRB or other bacteria in deposits associated with corrosion does not conclusively establish a casual relationship between the bacteria and the observed corrosion. of February 21-23, 2017 Mark Anderson-MTS 63

64 Definitions of terms (continued) MIC (continued) Metal loss due to MIC can not be established with just a positive test showing the presence of bacteria. Visual testing must be conducted to verify the cause of the metal loss. February 21-23, 2017 Mark Anderson-MTS 64

65 Key to Success Consistent data gathering February 21-23, 2017 Mark Anderson-MTS 65

66 Question When should you be called to evaluate the pipe? February 21-23, 2017 Mark Anderson-MTS 66

67 Sample Log for Shipping February 21-23, 2017 Mark Anderson-MTS 67

68 Remaining Strength Evaluate or calculate the remaining strength at locations where corrosion defects are found using one of the following methods. ASME B31G RSTRENG DNV Standard RP-F101 February 21-23, 2017 Mark Anderson-MTS 68

69 ASME B31G Remaining Strength Must use calculations NOT tables Most conservative RSTRENG The smaller the increments, the higher the predicated failure pressure Interaction rules DNV Standard RP-F101 February 21-23, 2017 Mark Anderson-MTS 69

70 Definitions of terms Calculated Failure Pressure The calculated pressure at which a pipe will fail due to metal loss. This is a calculation can be done by using any of the following methods. ASME B31G ASME Modified B31G Effective Areas February 21-23, 2017 Mark Anderson-MTS 70

71 Definitions of terms (continued) Calculated Failure Pressure (continued) ASME B31G Lowest Pressure Modified ASME B31G Higher Pressure Effective Area Highest Pressure February 21-23, 2017 Mark Anderson-MTS 71

72 Thank You! Questions? February 21-23, 2017 Mark Anderson-MTS 72