01 12 15 afd transverse flux technology paper release

New Transverse Flux Technology For

On-Line Inspection

Chris F Yoxall General Manager

ROSEN Australia Pty Ltd A ROSEN Group Company

(Inspection services for pipelines and hydrocarbon production facilities)

Traditional inspection technology for On-Line Inspection of Pipelines has difficulties detecting narrow longitudinal shaped defects. These types of defects are usually too narrow to be detected by normal Ultrasonic Technology or by Magnetic Flux Leakage Technology. ROSEN has developed Transverse Flux Technology and this induces the magnetic field in transverse direction, perpendicular to the longitudinal axis of the pipeline. Narrowly shaped longitudinal type defects are now clearly detected and can be sized accurately. This development is a step closer to the ultimate ability to detect and size all possible pipeline defects economically.

ROSEN 16inch size (AFD) Axial Flaw Detection tool.

New Transverse Flux Technology For

On-Line Inspection Table of contents 1 Introduction 2 Which defects can hardly be detected presently and threaten the

pipeline integrity 3 Why can these longitudinally shaped defects not be detected by

traditional Ultrasonic technology or by Magnetic Flux Leakage technology

4 Explain the virtues of the new Transverse Magnetic Flux Leakage

technology 5 Inspection results of ROSEN Axial Flaw Detection (AFD) tool 6 Conclusion

By Chris F Yoxall General Manager

ROSEN Australia Pty Ltd (A ROSEN group company)

At the occasion of the

Australia Pipeline Industry Association Convention

New Transverse Flux Technology For On-Line Inspection

1. Introduction Traditional inspection technology for On-Line Inspection of Pipelines has difficulties detecting narrow longitudinal shaped defects. These types of defects are usually too narrow to be detected by normal Ultrasonic Technology or by Magnetic Flux Leakage Technology. This new Transverse Flux Technology induces the magnetic field in transverse direction, perpendicular to the longitudinal axis of the pipeline. Narrowly shaped longitudinal type defects are now clearly detected and can be sized accurately. The development of Transverse Flux Technology is a step closer to the ultimate ability to detect and size all possible pipeline defects economically. ROSEN applied Transverse Flux Technology commercially with great success and we want to share this information as follows:

Which defects can hardly be detected presently and threaten the pipeline integrity.

Why can these longitudinally shaped defects not be detected by traditional

Ultrasonic technology or by Magnetic Flux Leakage technology.

Explain the virtues of the new Transverse Magnetic Flux Leakage technology.

Share the inspection results using our new Axial Flaw Detection (AFD)

tool.

Conclusions.


2. Which defects can hardly be detected presently and

threaten the pipeline integrity The type of defects consist of:

Long axial defects Longitudinal seam weld defects Cracks

Any of these longitudinal defects are particularly a threat to the integrity of the pipeline for two reasons: they are in longitudinal direction and they are long. The hoop stress in the pipeline wall is twice the longitudinal stress due to internal pressure (neglecting external loads).

The full thickness pipe wall material around shorter corroded defects compensate for the localized metal loss. This effect limits the risk of pipe wall failure to a workable level. Longer defects lack that compensating effect and the risk of pipe wall rupture increases to beyond acceptable levels. Pipe wall rupture is usually the failure. Pipe rupture has a very dangerous propagating effect in gas lines particularly.



threaten the pipeline integrity (Continued)

Long axial defects Examples of presently known long axial defects are so called channel type corrosion and faulty coating application type corrosion. Channel type corrosion is internal pipe wall surface corrosion in the bottom part of the pipeline typically caused by aggressive components in liquid pipelines operating at low flow velocity (< 0.8meters per second / < 3feet per second). Under these conditions, corrosion may generate long and narrow channels along the internal surface of the 6 oclock position in the pipe bottom. These can be as long as 3 meters and as narrow as 3 5 millimeters. NOTE Terminology on pipe wall defects:

Internal pipe wall surface defects External pipe wall surface defects Mid wall defects

Channel corrosion can hence be predicted when the conditions are right. It starts usually at the lower areas just upstream of upwards inclines, exceeding a 10% clime. Traditional Magnetic Flux Leakage inspection tools can indicate this phenomenon as they can usually detect the beginning and the end of these channels. These detected defects combined with the knowledge of the right ingredients of this phenomenon (being: low flow, aggressive components and low areas in the topographic profile of the pipeline routing) can be further investigated by digging up an expected location. Faulty coating application type corrosion may occur when coating is wrinkling around the pipe, causing improper bonding. This can cause long and narrow corrosion along these wrinkles at the external surface of the pipe wall. These type of defects are usually found when the traditional Magnetic Flux tool reports external pipe wall surface corrosion at random orientation around.

New Transverse Flux Technology For On-Line Inspection.



Longitudinal seam weld defects

These defects can be: Long single defect in the middle of the seam weld

Many short defects near to the seam weld grouped together

Long single weld defects are most probably manufacturers faults that have slipped through the QC system. Being subject to pressure and temperature cycles, they may lead ultimately to pipeline failures. As such, they must be found and monitored/repaired.




Improper bonding of the coating in the weld area can cause multiple defects in the heat-affected zone. It is more often seen when the coating is a tape wrapping application. This is a progressing condition and must be found.

Cracks Cracks are also limited to certain conditions only.

Fatigue cracking in dent areas

Fatigue cracking in corroded areas Lack of bonding in welds HIC cracking SCC related circular or longitudinal cracking

In summary:

Long axial defects Longitudinal seam weld defects Cracks

Almost all of the above-mentioned defects can be either predicted or their existence can be found (but not sized) by traditional inspection methods.


3. Why can these longitudinally shaped defects not be

detected by traditional Ultrasonic technology or by Magnetic Flux Leakage technology

The pipeline inspection industry has presently two main inspection methods; Ultrasonic and Magnetic Flux Leakage. Both of these standard methods can normally not detect defects with a long and narrow shape in longitudinal direction reliably. Pipeline inspection tools operating Ultrasonic technology lacks either the resolution or the sensor diameter is too large to detect very narrow or small defects. Ultrasonic technology can only be used in slow-speed pipelines (>1.2meters per second) and in liquid pipelines. ROSEN uses Magnetic Flux Leakage type technology. This technology is applicable to all pipeline services without any major limitation. It detects all defects as long as they generate a disturbance in the longitudinal induced magnetic field. This is positively the case with defects from pitting corrosion as small as 3mm of only 10% deep to any corrosions of larger and deeper size. The reason, why these narrow longitudinal type defects are difficult to detect with this MFL standard technology, is that the pipeline wall is magnetized in longitudinal direction. Any defects in the longitudinal direction that are narrow do not generate sufficient disturbance to the magnetic flux field to be noticed positively. This is particularly the case for straight cracks in true longitudinal direction. As mentioned earlier, channel type corrosion may be concluded from deduced information on the phenomenon knowledge and detection information.


4. Explain the virtues of the new Transverse Magnetic Flux

Leakage technology The Transverse Magnetic Flux Leakage technology is based on magnetizing the pipe wall in circumferential direction rather than in the traditional longitudinal direction. Narrow defects in longitudinal direction create a very visible disturbance to the circumferential induced magnetic field. They are now very easily detected and sized.

As in the longitudinal induced magnetic field tool, it can be seen that the effect on the magnetic flux disturbance is about three bigger than the actual defect. It is almost as if the defect is magnified. This is the result of very high resolution in both directions. Initial development tests indicated the absolute necessity for very high-resolution type technology.



Leakage technology (Continued)

Transverse Magnetic Flux Leakage (TMFL) Service is provided by: Data collection tool (AFD) Axial Flaw Detection Data processing Reporting Specifications data collection tool AFD: Very high resolution, full 360 degrees circumferential sensor spacing 2.9 mm (576 sensors for 16inch size tool) Pipeline Products: Any Max Pipeline Pressure: 15 MPa Pipeline Temperature: 0 - 65C Tool Velocity: 0.5 - 3.0 m/s Minimum Pipeline Bend Radius: 1.5 D Wall Thickness (for 16): 4 - 13 mm Maximum Run time (for 16): 116 h Maximum Inspection length (for 16): 280 km Sensitive to find small dents.

Handling specifications for a 16inch size tool: Tool Length: 2.77 m Tool Weight: 400 kg Transport Weight: 1,010 kg. the circumference of the pipe. Dig up information confirms the wrinkle type coating defects.



Leakage technology (Continued)

Data processing and evaluation Processing and evaluation of recorded data are essential elements for successful inspection services and require sophisticated software Basic design requirement: Inspection services must produce reliable and accurate information about the defects location, type and size. Important programs for enhancing the collected data: (FEM) Finite Element Method calculations Digital Mock up New consolidated findings in materials technology Equally important, it must be designed for possible future developments. The service cannot yet be called a crack detection service, as we have no proof presently that it can detect closed cracks reliably but we have successfully detected cracks with a 0.1millimeter opening. The software is capable of sizing also closed cracks and we will keep you up to date on the developments in this field. Reporting Minimum detection level for Axial defects: Length 25mm Depth 20% of wall thickness Width 0.1mm Minimum detection level for other defects: Pits and general corrosion 20% of wall thickness (POD) Probability of Detection 90% Sizing accuracy: Length +/- 25mm Depth +/- 15% of wall thickness Width (narrow defects) +/- 0.2mm Width (Pits, etc.) +/- 25mm.



Leakage technology (Continued) In hard copy and in the client friendly software format of ROSOFT ROSOFT for AFD is completely compatible and interchangeable with all inspection services information: Electronic Geometry Inspection Corrosion Inspection XYZ mapping services


5. Inspection results of ROSEN Axial Flaw Detection (AFD) tool

We have tested our equipment in pull tests and we have performed slightly under 1,000kms of runs under commercial conditions successfully. The reason why we were so instantly successful is that there is no significant change in the inspection tool with the traditional Magnetic Flux Leakage inspection tool other than the transverse placed magnet unit. This means that running performance of the tool is similar to the traditional design. These running conditions are very important for the performance quality of the inspection. We drew a lot of experience from the 100,000 plus kilometers that we run with the traditional longitudinal induced magnetic flux tools. The pull tests are particularly interesting as they were compared with results by High Resolution Traditional MFL tools. The following pictures show achieved inspection results:


5. Share the inspection results using our new Axial Flaw Detection (AFD) tool (Continued)

AFD capability can be included on other inspection service tools (Traditional MFL and XYZ Mapping Tools) The decision to combine should be based on careful technical and commercial considerations. Stand alone AFD service is usually the most economical and practical solution after earlier inspections. We have simulated a number of crack type defects, as they are most interesting to the industry. The following pages contain pictures of the inspection and sizing results of those types of defects. The top picture on each following page shows the line plot of the signal strengths while the bottom picture is a color representation of the magnetic flux level behavior.

New Transverse Flux Technology For On-Line Inspection.




When is it most practical to use TMFL?


6. Conclusion This transverse technology (TMFL) adds a very useful service to the available standard technology of using longitudinal induced Magnetic Flux Leakage (MFL) method. The Axial Flaw Detection (AFD) service is an economic addition and could be used in addition to the traditional inspection method but only however when it is absolutely necessary. This new technology is again a step closer to the ultimate ability to detect and size all possible pipeline defects economically.

It further reduces the risk of leaving un-detected

pipeline integrity threatening defects.

On-Line InspectionTable of contents

01 12 15 afd transverse flux technology paper release

Documents

longitudinal defects

type of defects

possible pipeline defects

types of defects

normal ultrasonic technology

transverse direction

pipeline integrity

longitudinal direction