solution: boiler tube weld inspection

1© Zetec Inc. All rights reserved

Boiler Tube Weld

Inspection

Application Solution

Overview

• Inspection Challenge

• Recommended Phased Array Ultrasonic (PA UT)

Solution

• Results – Comparison with Radiography (RT)

• Benefits of Zetec Solution

© Zetec Inc. All rights reserved 2

• The industry requires a rapid volumetric nondestructive evaluation (NDE) technique for boiler tube welds, to minimize outage time and budget

• Traditionally, radiography (RT) is used, but has several drawbacks :

Inspection Challenge

© Zetec Inc. All rights reserved

– RT is insensitive to planar defects,

if angle between planar flaw and

beam is > 8°

– No immediate feedback for welder

– RT is disruptive to other activities

– Safety regulations are getting more

severe worldwide

3

• Encoded Phased Array UT offers a reliable and efficient

alternative volumetric inspection solution “in Lieu of RT”

• Solution to deal with low clearance, variety of diameters,

and the presence of weld caps :

‒ Circ-it Scanner

‒ Low Profile Probes & Wedges

‒ Flexible Inspection Technique

Recommended PA UT Solution


• Circ-it scanner (from Jireh Industries) :

one-axis manually encoded scanner

• Variety of diameters:

from 21.4 mm to 114.3 mm (0.5” to 4.0” NPS )

• Low-profile design : radial clearance 11 mm

• Modular and flexible design:

– Quick change links for infinite adjustment

– Single or dual probe scanning configuration

• Cable management system for irrigation lines and

probe cables

- Scanner


- Scanner


• Extra thin 1D linear array probe: 11 mm (0.433’’)

• Curved array for optimized focusing in thin tubes:

r = 35 mm

• Designed for sectorial scanning

• Multiple probe frequencies available

– 5 MHz for rough inspection surfaces (with OD pitting)

– 7.5 MHz for standard inspections

– 10 MHz for optimized detection and characterization of

small volumetric indications (porosities, slag...)

• Choice of 16 or 32 elements to optimize steering

capability

Low Profile Probes


All probes with ZPAC connector, dual connector optional,

recommended generic probe highlighted

Probe TypeFrequency

(MHz)

Number of

Elements

Pitch

(mm)

Active

Aperture

(mm x mm)

ZPA-PB1D-AT-5MHZ-16-REX-2.5M-ZPAC

ZPA-PB1D-AT-7.5MHZ-16-REX-2.5M-ZPAC

ZPA-PB1D-AT-7.5MHZ-32-REX-2.5M-ZPAC 7.5 32

5 16

8 x 10

0.5 8 x 10

7.5 16 0.5 8 x 10

0.25 8 x 10

10 16 0.5 8 x 10ZPA-PB1D-AT-10MHZ-16-REX-2.5M-ZPAC

ZPA-PB1D-AT-10MHZ-32-REX-2.5M-ZPAC 10 32 0.25

Low Profile PA Probes


• Extra thin assembly: 11 mm (0.433’’)

• Wedge kit to cover 0.5” to 4” NPS, and flat

• Interchangeable rexolite wedges

• Wedges optimized to minimize the distance

between probe and weld center line

• Irrigation and easy scanner interfacing

Low Profile Wedges


• High-speed inspection : acquisition

from 2 sides, in less than 1 minute

• One-line circular movement, with

sectorial scan for weld coverage

• Full skip inspection: capability to

use from 40° to 80°SW

• Accurate imaging using on-line

S-Scan and Dynamic Merge on

Zetec TOPAZ16 or TOPAZ32

PA UT instrument

• Examination methodology

adaptable to applicable

codes and requirements

Inspection Technique


Courtesy of RWE Power Intl.Ltd

Results – Comparison with RT




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Courtesy of RWE Power Intl.Ltd



• Coal Generators GENSIP Programme (UK) organized

Round-Robin NDT exercise (2013 – 2014) to assess

performance and reliability of PA UT

• 50 tubes with various diameters, and containing various

flaw types were inspected by 10 NDT service companies

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Two-dimensional scoring system : detection on X-axis, sizing

and characterization on Y-axis

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• PA UT can detect all weld defect types, but better suited for

planar defects : lack of root fusion, lack of root penetration, weld

toe crack, weld root crack

• RT is better suited for volumetric defect types: porosity, inclusion

• Education on expected flaw types is important : well-trained PA

UT operators will have success for defect characterization on all

defect types, for wall thickness > 7 mm

• PA UT can have some difficulty to characterize volumetric defect

for small thickness (< 7 mm)

• Weld overlay is important to help position and diagnose flaws

• PA UT offers some through-wall sizing capability, length sizing is

less accurate than for RT (over sizing)


Results – Summary

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Benefits


• Phased array UT can detect all defect types, and offers

through-wall sizing capability

• Non-disruptive to other activities

• scanner, industrially proven design,

adapts to a wide variety of boiler tube diameters

• and integrated units,

compact and easy to setup

• UltraVision Touch™ on-board software, guarantees an

efficient inspection workflow, from set up to analysis and

reporting

solution: boiler tube weld inspection

Engineering