PipeWIZARD

Automated ultrasonic phased array pipeline girth welds inspection system

• Fast scanning speed: 100 mm/s
• Weld-to-weld inspection time of less than four minutes for 36-inch pipe
• Very flexible for different pipe diameters, wall thicknesses, and weld profiles
• Low operating costs
• High reliability
• Great for special scans

PipeWIZARD®
Girth Weld Inspection System Overview

Gas pipelines are made of high-strength steel and operate at a significant percentage of their yield strength. Pipes are girth-welded on site, typically using automated welding systems. They are then rapidly inspected, coated, and buried. Due to the demanding construction cycle, it is important that weld defect be detected and analyzed very quickly.

In the last several years, automated ultrasonic testing (AUT) has begun overtaking traditional radiography as the choice pipeline weld inspection method throughout the world. This gain in popularity is mainly because AUT offers better detection and sizing accuracy, leading to lower rejection rates.

There are a number of specific constraints related to the gas pipeline construction cycle:

1. Time: Onshore, the inspection cycle (mounting the scanner, scanning, returning, removing the scanner, driving to next weld) is under four minutes.
2. Offshore, the time can only be two minutes, but moving is not required.
   Data analysis: Data must be analyzed before moving to the next weld. This means characterizing the weld as accept/reject almost in real time.
3. Data storage: It is essential to store the data during the inspection cycle for regulatory purposes.

All these specific constraints are addressed by AUT.

Codes

Calibration block containing flat-bottom holes (FBH) and other reference reflectors (ASTM 1997).

In 1998, the ASTM published the E-1961-98 code, which covers key elements of automated ultrasonic testing of girth welds-zone discrimination, rapid data interpretation, specialized calibration blocks, and configuration procedures. The E-1961 code is designed for engineering critical analysis (ECA). Similarly, in 1999, the American Petroleum Institute (API) published the 19th edition of Standard 1104, which covers mechanized ultrasonic testing and radiography of girth welds.

All PipeWIZARD® products comply with the ASTM E-1961 code, and by inference, with the API 1104 standard. As well, PipeWIZARD products also comply with the DNV2000 OS-F101 standard, the offshore AUT code. Under some circumstances, company specifications may override the codes, typically by asking for improved sizing or better resolution.

Advantages and Key Features of AUT

AUT is gradually replacing radiography for pipeline girth weld inspections worldwide. The advantages of conventional AUT are clear:

• No radiation hazard.
• Better process control of welding, yielding lower rejection rates.
• Larger defect acceptance using ECA, also giving lower reject rates.
• Faster inspections.
• Rapid and reliable data interpretation from special output display.
• Overall, onshore mechanized ultrasonics offer a better inspection solution with lower rejection rates than radiography.

Advantages of Phased Arrays for Girth Weld Inspections

Phased arrays offer major advantages over conventional AUT.

• Smaller and lighter probe pans with potentially reduced cutbacks (down to 2 in.).
• One PipeWIZARD® can scan pipes ranging in diameter from 2 in. to 56 in. while only changing the band, setup file, and wedge.
• The standard PipeWIZARD can scan pipe walls from 6 mm to 50 mm (0.25 in. to 2 in.).
• Increased number of zones for better detection and vertical sizing.
• The scan time is reduced by several seconds due to the narrower probe pan.
• Any weld profile, pipe diameter, and wall thickness can be accommodated by recalling the appropriate setup files.
• Arrays can be programmed to perform real coupling checks using the back wall.
• The setup wizard enables automatic setups.
• Special applications (see next page).

Near Real-Time Output Display

• The scrolling display is designed for rapid interpretation and analysis by operator.
• Welds are "opened out" to display upstream and downstream sides.
• Each zone is displayed as a twin-gate strip chart, with the amplitude and time of flight (TOF).
• B-scans display and characterize porosity of root and cap regions.
• The optional time-of-flight (TOFD) display improves misoriented defect detection and sizing.
• Colored strip charts on the right side of the screen show coupling status.
• Up to 128 channels are possible.

Zone discrimination of a J-bevel type weld profile in a 19.1-mm calibration block.

What Are Phased Arrays?
Phased arrays use electronic beamforming to generate and receive ultrasound. Each element in the array is individually pulsed and delayed to create a wide range of beam angles and focal distances.

A series of focal laws are developed, enabling weld scanning in a manner similar to conventional ultrasonics, but with only two arrays and with much greater flexibility. Setups are performed by loading a file, not by adjusting transducer positions. Electronic scanning permits customized weld inspections, including multiangle TOFD, advanced imaging, and detailed inspections.

Automatic interpretation software.

Output display from weld with defects.

Defect Analysis

• Amplitude data is color coded to alert the operator when a signal crosses the rejection threshold.
• Defects can be rapidly sized by counting the number of zones where the signal is detected.
• Defect length can be measured directly from the screen.
• Defect location in the weld can be determined from the time-of-flight information (colored bar).
• Characterization is performed using amplitude, zones, and TOF data from the appropriate zone(s) and TOFD.

Complete zone discrimination can be performed with two 60-element arrays, one on each side of the weld. TOFD and other scans can be performed using the same arrays, or dedicated probes. The probe pan is designed to accommodate the additional probes required to perform transverse inspections. Additional sizing techniques can be used, such as TOFD or amplitude weighted techniques.

Welds to Inspect

Ring-type scanner covers a range from 2 in. to 16 in.

Calibration
The calibration block is complex -it contains reflectors to simulate defects expected in the field. For a CRC-Evans profile:

• Notches used for root and cap
• Angled FBHs used for LCP, fills, and hot passes
• Vertical through-wall holes used for positioning

Ultrasonic Zone Discrimination

• The weld is divided into zones, each 1 mm to 3 mm deep, for root, LCP, fills, and hot passes.
• Welds are inspected from the upstream and downstream sides for 100% coverage.
• Each weld zone is inspected in pulse-echo or tandem modes.
• The beam overlap from zone to zone is minimal.
• Reflectors detected in a single zone can be accurately sized as 2 mm or less.
• Twin gates are used for each channel for amplitude and TOF

Typical Defects to Be Detected

• Lack of fusion (surface or subsurface)
• Incomplete penetration
• Centerline solidification cracking
• Cap and fill porosity
• Hi-low
• Misfire
• Burn through
• Root porosity
• Root undercut

Special Applications

• Thick pipes
• Small-diameter pipes
• Cladding
• Seamless pipes
• Tendons
• Risers
• Double jointing
• Challenging weld profiles

In-Service Applications
PipeWIZARD® is used in a number of onshore and offshore applications and has completed over 200,000 welds and scans to date. The largest applications where PipeWIZARD was used was the Blue Stream project with Saipem, for which 65,000 welds and 130,000 scans were performed, and the 4000-km Chinese WEPP project.

For Blue Stream, PipeWIZARD ran for several months with no downtime. PipeWIZARD operated flawlessly in hot and cold climates; in humid, salty, and dry conditions.

PipeWIZARD® Delivers

• Real-time display and data analysis
• Automatic data recording
• TOFD scans for improved detection and sizing
• Accurate defect sizing to the depth of one zone (1 mm to 3 mm) or better using TOFD
• Precise measurement of defect length
• Defect location in weld fusion line or centerline
• Correct defect characterization
• Special scans for specific defects: B-scans for porosity and tandem probes for centerline cracking
• Optional top, side, and end views, or alternative
  displays

PipeWIZARD® System Specifications

System Description

• Downsized probe pan containing two linear arrays
• Mechanized drive clamping onto welding band
• Large umbilical cable connecting probes, encoder, power, and couplant lines to instrumentation
• Instrumentation console including computer, pulsers, and motor drive
• Couplant containers, pump, and reclamation unit

Probe Pan

• Probe pan contains two linear arrays.
• Extra modules are available for transverse and TOFD inspections.
• Couplant is pumped water or water-methanol in cold climates.
• Lifting lever allows rapid rotation and minimizes possible damage.
• Encoder running on welding band gives
  circumferential position.

Instrumentation
The instrumentation consists of:

• Motor drive unit
• Tomoscan FOCUS™ 32:128 phased-array unit
• Industrial computer
• Specific PipeWIZARD® software for data acquisition, analysis, and reporting
• Automatic marking of indications exceeding rejection threshold to assist operators
• Inspection reports and list of defects adapted to client requirements
  Automatic data saving to two separate media in real time