development indigenous instrumented pig – a success story

Development Indigenous instrumented Pig – A Success

Story

Overview of Presentation

Introduction

Development of Instrumented Pig

Development of Testing Infrastructure

Evaluation of IPIG in Wet test loop and pipelines

Lesson Learning and successful development

Inspection of Pipelines

Conclusions

Introduction

Above 40,000 km pipeline network is existing in India to transport

petroleum products, crude oils and natural gas

It is Immensely important to maintain the pipelines in healthy

condition for safe operation over a long period

Pipelines are protected by using good quality coatings to avoid direct

contact with surrounding soil supplemented by CP system to protect

from corrosion

Pipelines are also Inspected using inline inspection tools, popularly

known as instrumented pig (IPIG), to monitor their health

Instrumented Pigs

Widely used for inline inspection of cross country pipelines for

monitoring their health.

IPIG travels through pipeline with the propelling force of the

fluid being transported

After the inspection run, data is downloaded and interpreted

using the closely guarded data analysis software package

Analysis provides information of all pipeline features such as

valves, fittings, weld and metal loss with fairly good level of

defect sizing and within ± 1 to 5 meter of locational accuracy

Indigenous Development

IndianOil-R&D, in association with BARC, developed MFL based

Instrumented Pig Technology for the first time in the country.

Extensive research work carried out in designing, development of

components, modules and integrated tools and evaluation facilities

Exhaustive evaluations of IPIG for negotiability, endurance, wear and tear,

shock, vibration and data acquisition capability

Instrumented Pigs of 12” & 14” size commercialized. Development of

18” & 24” IPIG completed and is under testing and evaluation.

Technology and tools for inspection of other sizes and applications are

planned for development.

12” Instrumented Pig

00225222

12” Caliper Pig (CPIG)

14” Instrumented Pig (IPIG)

24” Caliper pig (CPIG)

24” Instrumented pig (IPIG)

P

P

P

N S

Basic Principle of operation of IPIG

Hall Sensor

Pipeline Wall Thickness

External Metal LossMagnetic flux lines

Strong permanent magnets (NdFeB) are used to magnetize the pipe wall

Magnetic flux leaks due to: • Presence of metal loss on the pipe

wall.• Existence of extra ferrous material

near the pipe wall.• Any change in properties of the pipe

wall material Primary sensors and secondary sensors

sense magnetic flux leakage. Secondary sensors detect internal defects

Specification of Indigenous IPIGs

Sr. No Description Remarks

1. Axial sampling (mm) 2.32 mm (changeable w.r.t. flow rate)

2. Continuous recording 350km

3. Primary & Secondary sensors (Nos.) 72 & 56 for 12” and 84 & 72 for 14”

4. Odometers 3 Nos.

5. Location accuracy (meters from nearest marker) 0.1%

6. Minimum detectable defect (Length X Width X %WL) 2t X 2t X 10% TH, t = 6mm

7. Confidence of detection (% of total defects) 90

8. Confidence of characterization (% of detected defects) 90

9. Confidence of differentiating internal and external defects (% of detected defects)

80

10. Minimum detectable defect in thicker pipe 3t X 3t X 20% TH, t = 9, 12 mm

11. Minimum pipe bend (radius) 5D, D = Nom. Dia.

Defect Sizing and Location Accuracy

Types of metal loss Definition

Minimum Sizing

Accuracy

Depth Sizing

Accuracy

Length Sizing

Accuracy

Width Sizing

Accuracy

Pitting Corrosion < 3tx3t +0.15t +0.15t +12mm + 12mm

General Corrosion > 3tx3t +0.1t +0.10t +15mm + 20mm

Axial Grooving +0.20t +0.20t +15mm + 12mm

Circum. Grooving + 0.15t +0.15t ±12mm + 20mm

Locational and Orientation Accuracy

Axial position accuracy from reference marker 1:1000 mts.

Circumferential position accuracy ±150

Evaluation facilities

Need of Evaluation Facilities

Development of inspection technology

To generate design data for components

To carry out functional tests on mechanical and electronic components

Carrying out Pre and Post inspection activities

Functional check

Data check

Data completeness

Data quality etc.

Validation to qualify for inspection

Verification of results obtained from testing based on full scale data bank

Continuous improvement in capabilities of tools

Evaluation Infrastructure

Facilities to generate design data :

Static rig

Rotary rig

Facilities to evaluate functional checks such as negotiability,

endurance & data acquisition capability:

Linear Pull through rig

Hydrostatic testing rig

Wet test loops of various sizes

Static Test Rig

Purpose: Designed to study MFL levels around a

test section made of pipe material of dimension of 320 mm (length) x 125 mm (width).

Details: One sub-assembly of magnetic module

consisting of backing iron, brushes, test section and two NdFeB magnets are fixed on the table.

Hall sensors are used to detect the leakage flux.

The entire area over the test section is scanned and deformity data is captured.

Rotary Test Rig

Purpose: Rotary test rig is used to study the

effect of velocity on metal defect signal in the laboratory.

Dynamic testing of sensors and its repeatability can also be checked.

Details: The 28” drum is rotated on four

wheels. The speed of drum can be changed.

Two sub-assembly of magnetic module having four sensor modules in each, is placed on the drum.

The data is acquired Defects of different sizes are made

to generate databank.

Linear Pull - Through Rig

Purpose: Dry evaluation of mechanical

components and module of prototype IPIG

Generation of database for defect characterization (studying the electronics and data acquisition system)

Details: The rig consists of 25 mtrs. length of

actual field pipelines. A semi cylindrical SS launching/

retrieving trays are connected to a reducer at either end of the rig to retrieve the pig.

A motor drive gearbox assembly winches the pig through the linear pull through rig with the help of a wire rope.

12” Wet Test Loop

Purpose :Proving mechanical negotiability of various types of PIGs, through pipe fittings Mechanical endurance testing on mechanical componentsGenerating signatures of various pipe fittings and metal loss defects under simulated field pipeline conditionDetails:Length -120mFlow rate 0 – 200m3/h5D and 6D bends

When PIG passes PS1Valves V1, V3 & V2 openedValves V4, V6 & V5 closed

When PIG passes PS2Valves V4, V6 & V5 openedValves V1, V3 & V2 closed

12” Wet Test Loop – Flow Scheme

24” Wet Test Loop

Purpose:Proving mechanical negotiability through pipe fittings Endurance testing on mechanical componentsGenerating signatures of various pipe fittings and metal loss defects under simulated field pipeline conditionDetails:Length - 444mFlow rate 0 – 2400m3/h5D bends

Spools for Negotiability

311-275-311

12 mm Protrusion

Pipe Spool with External defects

Defect Creation Machine

Creation of defects on 12”, 14”, 18” and 24” pipes

Defect on external surface of any size and shape

Hydro Test Facility

Purpose For pressure testing

of Data Acquisition system and other modules

Details: Length – 3m Sizes and thickness

of vessel – 24” (OD) x 0.375”(WT)

Max. test pressure – 100kg/cm2

Evaluation in Wet Test Loop and Actual

Pipelines

Gauge Pig Run

Improvements in Compressibility of Magnetic module Development of 12” IPIG

Gauge plate launched in Pipeline section with geometry of 12” pipelines: OD: 324mm ID: 311mm (for 6mm WT) ID: 298 mm (for 12mm WT)

Gauge Plates Size275mm, 280mm, 285mm

Plate received like Saucer shapeProject abandoned and magnetic module was redesigned

Gauge Pig Run in WTL

Gauge Pig Run – Run in HM section

Gauge Pig Run – Run in DP section

Mechanical Negotiability

Mechanical Components Such as:

Poly Urethane Cups

Brushes

Sensor Mounting arms

Odometer wheels

Tow Links

Endurance Testing to Check Wear and tear

Success after Few Failures in Wet test loop

and Pipeline runs

Evaluation of IPIG with Dummy Sensors

Evaluation of IPIG in WTL

Dummy IPIG fitted with PU cups tested

in Wet Test Loop for ascertaining

behavior of cups, sealing and wear &

tear.

Based on testing, performance

specifications of PU cups drawn.

During initial trial runs, wear & tear of

cups was excessive.

Material properties like type of

material, hardness, tear resistance,

abrasion loss etc improved.

Improvements in Mechanical components – PU Cups

Side View of Retrieved IPIG (after wash) showing damage to Cups

PU Cups of IPIG (During evaluation in AB section)

Initially, potted wire brush were

used for directing the magnetic

field to the pip wall.

Performance of Wire brush was

studied in Wet Test Loop and field

pipelines.

Poor negotiability was observed at

weld protrusions, bends and heavy

wall thick pipe regions.

Material properties like type of

material, hardness, tear resistance,

etc improved.

Improvements in Mechanical components – Wire Brush

Brushes after Testing (During Evaluation in MA section)

Brushes and Primary Sensor Arms(During evaluation in MA section)

PIG locator Module(Failure of Tow Link and PU CUP)

IPIG stuck at the Insulating flange (During Evaluation in MA section)

Close up of IPIG front after Close up of IPIG front after dismantling of scrapper Barrel.dismantling of scrapper Barrel.

Retrieval of IPIG Tool with help of Retrieval of IPIG Tool with help of Chain Pulley BlockChain Pulley Block

Retrieval of IPIG (During evaluation in AB section)

Swiveling action at odometer base was

removed

Odometers of large wheel diameter were

employed to reduce slippage Mounting of odometer assembly at the rear of pig

locator module to avoid fouling/ obstruction

Employing double sided support arm for odometer

wheel to have better stability and strength Adopting different method of sensing distance by

employing inductive type proximity switch (better

sensing, less muck deposition so less tendency to

jamming)

Improvements in Mechanical components - Odometers

Uniformity in spacing between sensors

Mounting of sensor assembly on SS

mounting ring between centre of backing

iron assembly employed to achieve full

periphery coverage

Non magnetic high spring steel sensor

mounting plate used to have 100%

contact with pipe wall

Sensor wear plate modified to

withstand high wear

Improvements in Mechanical components –Primary Sensor Assembly

First generation single board computer based DAS –

Pentium based CPU card with 16 channel data acquisition

card, multiplexer & flash disk

Second generation Digital Signal Processing (DSP)

system with 02 nos. DSP processor based 80 channel data

acquisition card for data storage & Flash disk for storage

Third generation Microcontroller based data

acquisition card with on board storage on flash chips(ICs) &

flange mounted cards for cleaner interconnections and to put

DAS and battery in a single module reducing IPIG to 3

modules pigable distance ~400kms

Developments in Electronics

Comparison of Results (Static, LPT Rig & WTL)

Notch Size, mm

Radial F. D. P-P Gauss - SR

Radial F. D. P-P Gauss - LPT

Radial F,. D. P-P Gauss - WTL

Span(mm)

18 x 18 x 2 230 128 67 18/24/18

18 x 18 x 3 235 176 - 18/20/-

18 x 18 x 4 - - 119 16

24 x 24 x 2 235 176 104 24/45/28

24 x 24 x 3 295 224 - 24/45/-

24 x 24 x 4 - 496 173 -/26/22

24 x 24 x 5 - 576 - -/26/-

Summary of Field Trial Runs

Sr. No. Date Summary/modifications carried out after field trial

1. Sept. – Oct’

2000

Switch over to time sampling in case all the odometers fail to work

Tow-links, cups strengthened

2. 1st week

Jun’ 01

No damage to tow – links and PU cups

1.6 GB data acquired

Sensor shorted causing power supply to trip

Irregular odometer pulses

3. 2nd week of

Jun’ 01

3.7 GB data acquired for 47 kms

Sensor shorting due to sensor wear

Stuck at Allahabad pump station on weld protrusion at isolation

flange. Magnetic brushes re-engineered

Fuses provided to sensors to prevent trip of power supply due to

sensor shorting


4. Feb –

Mar’ 02

IPIG was launched and retrieved without mechanical

damage. No data acquired.

DAS failed to record due to excessive vibrations.

New Hard Disk mounting designed

5. Sept –

Oct’ 02

No data acquired. No mechanical damage to IPIG.

Hard disk is vulnerable to failure during vibration

Hard disk was replaced by Flash Disk and operating

system was housed in Disk-on-Chip.

6. Jun’ 03 4GB data was acquired in 74.6 kms

IPIG was retrieved without mechanical damage

Odometers improved after inconsistence performance.



7. Jun’ 04 No mechanical damage to IPIG modules

IPIG acquired 8 GB data

8. Dec’ 04 Consistent performance of all the three odometers

observed.

IPIG acquired approximately 8 GB data during the run

of 54.5 hrs and a travel of 140.2 kms approximately.

9. Jun’ 05 IPIG acquired 10GB data.

All odometers rotating freely.

The performance of IPIG run was satisfactory.

03 nos. of defects verified through dig site.


S. No. Section (km) Date of Inspection

1 Mugalsarai – Allahabad (147) December 2004

2 Patna – Mugalsarai (152) March 2006

3 Barauni – Patna (103) November 2007

4 Asansol – Barauni (100) April 2008

5 Mourigram – Rajbandh (110) 14th February 2009

6 Allahabad – Kanpur (196)8th-11th December

009

TOTAL = 808km

Inspection runs of 12” IPIG

S. No. Section (km) Date of Inspection

1 Patna-Mugalsarai (210) Nov’2006

2 Barauni-Patna (103) Nov’2007

3 Haldia-Mourigram (118) Feb’2009

TOTAL = 431km

Inspection Runs of 12” CPIG (2006-10)

MFL Signatures acquired by IPIG

General Features & Installations

Field Pipeline Wet Test Loop

Markers Markers

Welds Welds

Flanges Flanges

Area Starts Raised section

Area Ends Raised section

Supports Supports

Sleeves --

Clamps --

Taps --

Tees Tees

Attachments Attachments

Valves Valves

Metal Loss Metal Loss

Marker MFL Signature

Weld MFL Signature

Weld

Flange MFL signature

Valve MFL signature

Valve

Area End with weld

Weld

Area Start with weld

Weld

FlangeFlange

Sleeve MFL Signature

Sleeve Start

Sleeve End

Attachment MFL Signature

Area Start MFL Signature

Area Start of Bend

Area End MFL Signature

Area End of Bend

External Metal Loss

Results and Discussions

(Digsite Verification of Metal Loss defects)

Dig-site Verification

Tool validation is carried out by carrying out dig-site

verifications

Common method for evaluating in-line inspection results NACE Standard RP0102

API Standard 1163

Results of dig-site verifications confirms the capability of

tool and these results are also used for continuously

refining the data analysis procedures

Emphasis is given on physical dig-site verification and

taking measurements.

Defect Dimension Classification

Source: Specification & requirements for intelligent pig inspection of pipeline, Version 3.2, January 2005

A = Wall thickness or 10 mm (0.39”) whichever is greater

Basic Procedure(Verification Measurements)

1. Length and width of defect measured using Vernier scale of least count 0.02 mm

2. Depth (%WL) of defect measured using pit gauge of least count 0.1mm

3. O’clock position of defect is measured by eye estimation

4. Defect distance from nearest weld is measured using tape.

Conformable Eddy Current ArrayInspection system

Basic Procedure Corrosion depth adjustment

Depth adjustment for defects with background corrosion

Chainage (m)

Reported Actual

Length

(mm)

Width

(mm)

%

WL

Clock Length

(mm)

Width

(mm)

%

WL

Clock

73328.5 18 31 35 5:05 38 36 35 5:00

7334.87 9 20 42 5:25 9 18 40 5:30

130706.2 13 18 45 7:40 14 14 42 7:45

One mismatch in length observed

Digsite Verification (M-A section)

Defects Between Sleeves (Additional verification)

• A severe defect detected between sleeves at 73223.48m from Mughalsarai pump station.

• Defect: Length: 22 mmWidth: 20 mm%WL : 77% O’clock: 6:45

Metal Loss

1st Sleeve End 2nd Sleeve Start

2nd Sleeve End

1st Sleeve Start


FEATURE AT:130706.15 m

MM64 at 130178.22 527.93 1475.99 MM65 at 132182.14

10.70 11.42 11.10 2.85 9.16 11.39 11.25 11.36

11.1 2.9 9.14 11.4upstream downstreamLength 13.00 14.00 Width 18.00 14.00 %WL 44.00 41.7

Position 7:40 7:45

Note: Measured quantities are are indicated in colour.1. Figures in blue are pipe lengths measured by tape.2. Figures in green are defect dimensions measured by vernier scale.3. Figure in red is % depth of defect measured by pit gauge.4. Figure in orange is is an eye estimate of the o'clock position of defect.5. Very acurate log distance could not be acertained.

14

14

20 deg2.5

FEATURE AT:73334.33 m

MM36 at 73150.43 183.90 1814.75 MM37 at 75149.08

11.48 10.85 11.22 5.41 5.10 10.71 11.72 10.89

11.25 5.61 4.94 10.45upstream downstream

Length 9.00 9.00 Width 20.00 18.00 %WL 42.00 40.00

Position 5:25 5:30

Note: Measured quantities are indicated in colour.1. Figures in blue are pipe lengths measured by tape.2. Figures in green are defect dimensions measured by vernier scale.3. Figure in yellow is % depth of defect measured by pit gauge.4. Figure in red is is an eye estimate of the o'clock position of defect.5. Very acurate log distance could not be acertained.

80 degree

2.3718.00

9.00

Corroded pipe surface



Chainage (m)

Reported Actual

Length(mm)

Width(mm)

%WL

Clock Length(mm)

Width(mm)

%WL

Clock

120.07(u/s MM 308)

27 43 49 6:00 40 42 34 05:40

121.83(u/s MM 308)

22 35 47 4:05 20 50 32 3:30

202.94(u/s MM 312)

23 42 54 7:30 28 42 47 8:00

203.75(u/s MM 312)

25 39 58 7:30 25 38 42 7:55

Results within the tolerance limits

Dig-site Verification (P-M section)

Type of data Reported Max. value of parameter

Desired Accuracy

Distance from U/S girth weld

5.362 m 5.362 m

Distance from D/S girth weld

3.826 m 3.826 m

External / Internal External External

Length 31 mm 57 mm ±15 mm

Width 51 mm 136 mm ±15 mm

Depth 81% (5.14 mm)

68.3%(4.34 mm)

±10%

O’clock 11:15 10:00 - 12:00 ± 150 (30 min)

Remarks: The data in respect of depth, length and o’clock position are within the accepted limits. However there is variation in width

Defect at Ch. 175604.8m

Dig-site Verification (A-K section)


Desired Accuracy


5.156 m 5.156 m


4.032 m 4.032 m

External / Internal

External External



Depth 57% (3.62 mm)

64.09 %(4.07 mm)

±10%

O’clock 10:30 10:00 ± 150 (30 min)

Remarks: The data in respect of depth, width and o’clock position are within the accepted limits. However there is variation in length.




Desired Accuracy


4.532 m 4.532 m


4.656 m 4.656 m

External/ Internal

External External



Depth 54% (3.43 mm)

44.33%(2.81 mm)

±10%

O’clock 10:52 10:00 - 11:00 ± 150 (30 min)

Remarks: The data in respect of depth, length are within the accepted limits. However, there is variation in width



Dig-site Verification (D-P section)

Critical defect above 80% wall thickness loss reported at ch 5343.441m between major road crossing.

However, the metal loss was not observed during the dig-site verification.

The error in prediction was attributed to the sub surface defect and the pipeline was protected by providing sleeve.


Desired Accuracy


5.037 m 5.003 m


6.167 m 6.200 m


Length 15 mm 16.5 mm ±15 mm


Depth 32% (2.28 mm)

29 % ±10%

O’clock 10:20 06:50 ± 150 (30 min)

Remarks: The data in respect of depth, width & length are within the accepted limits. However, there is variation in o’clock position




Desired Accuracy


11.012 m 11.140 m


0.411 m 0.410 m




Depth 37% (2.642 mm)

21.33 % ±10%

O’clock 04:43 01:00 - 02:00 ± 150 (30 min)

Remarks: The data in respect of depth & length are within the accepted limits. However there is variation in width and o’clock position



Activity completed and major pilferage point at 37.580 km from Bijwasan has been identified & located.

Dig-site Verification (D-P section)Pilferage located by 14” IPIG in 2008

Activity completed and major pilferage point at 16.65 km from Bijwasan has been identified & located.

Dig-site Verification (D-P section)Pilferage located by 14” IPIG in 2009

Dig-site Verification (D-P section)Pilferage located by 14” IPIG in 20.05.2010

A major pilferage point at 94.40km from Bijwasan has been identified


Critical defect above 57% wall thickness loss reported at ch 98623m.

However, mill defect was (44-48%) observed during the dig-site verification.

The error in prediction was attributed to the sub surface defect

Site Verification ResultsChainage Length (mm) Width (mm) Depth (%)

ROSEN(2001)

IPIG A* ROSEN(2001)

IPIG A* ROSEN(2001)

IPIG A*

I (IPIG in 2005) Site verification results of M’ sarai – A’bad PL on the basis of IPIG data

73334.87 10 9 9 13 20 18 42 42 40

73328.5 18 18 38 27 31 36 38 35 35

130706.15 13 13 14 14 18 14 45 45 42

II (IPIG in 2007) Site verification results of Patna – M’sarai PL on the basis of IPIG data

121.83 (MM 308) 15 22 20 61 35 50 21 47 32

120.07 (MM 308) 21 27 40 27 43 42 32 49 34

202.94 (MM 312) 32 23 28 43 42 42 20 54 47

203.75 (MM 312) 22 25 25 36 39 38 22 58 45

III (IPIG in 2007) Site verification results of BRN – Patna PL on the basis of IPIG data

28033.921 46 29 20 58 76 55 41 73 72.8

28908.817 27 23 20 32 50 38 40 57 59.6

28932.797 27 22 25 32 49 35 36 60 66

A*: Actual results are within acceptable limits. Quality of data depends on the cleanliness of pipeline which affect the MFL singals.



Variation in Depth (Reported – Actual) - ROSEN Variation in Depth (Reported – Actual) - IPIG

Variation in Length (Reported – Actual) - IPIGVariation in Length (Reported – Actual) - ROSEN

Summary

IndianOil in association with BARC, have developed IPIG technology for the

first time in the country.

The developmental process has undergone various phases like

conceptualization, designing, fabrication, testing, improvements after failures

The 12” and 14” size tools used for inspection of 1000 km of liquid pipelines.

The 24” and 18” size IPIG and CPIG are under evaluation

IndianOil has also created full-fledged testing infrastructure for evaluation of

IPIG components and modules of various sizes

Development of newer technology and IPIGs and CPIGs of other sizes for

liquid and gas lines are being taken up

Acknowledgments

Thanks to Dr. R K Malhotra, Director (R&D) for continuous

support

Thanks to BARC- CnID team to provide development support to

IndianOil

Our Thanks to our Pipeline Division for providing Pipeline for

testing and evaluation

Thanks to Pipeline R&D Team :

For helping in preparing the paper

development indigenous instrumented pig – a success story

Documents

instrumented pig technology

instrumented pig00225222

pipe wall magnetic flux

inline inspection tools

detected defects

ipig travels

development of components

inspection run