Qualification and Industrial Application of Small Bore Ultrasonic Phased Array UT

Fraser Hardie

Doosan Babcock, Renfrew, United Kingdom

KINT Symposium on PAUT of welds in thin-walled materials

Shell technology Centre, Amsterdam – October 30-31 2019

Presentation Content

Introduction to Doosan Babcock NDT

History of SBPAUT at DB

Qualifications

Experience

Next steps

NDT at Doosan Babcock - Overview Team of 40 NDT techs/engineers/experts based in Renfrew, UK

NDT is a key element of our Asset Management portfolio

40+ years experience of auto NDT in the nuclear industry

35+ years experience in specialist NDT in O&G & thermal power applications

Fig 8.

Integrity

Management

Noise &

Vibration

Lifecycle

Support

NDT

Metallurgy &

Welding

Component

Testing

Event

Recovery

Data

Capture,

Analysis &

Reporting

Corrosion

Management

Asset Management

Bespoke Solution

Reasons for replacing RT with UT

Reliability of RT?

SFD

>25m

<10

t

Benefits:

Removal of health & safety hazard

Improved productivity

Immediacy of results

Compatibility with fitness-for-purpose criteria - accurate measurement of throughwall extent of flaws

Repeatability; permanent record

Limitations of RT

Doosan Babcock SBPAUT Timeline

0

5000

10000

15000

20000

2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

Cumulative total of tube butt welds

~15,000 welds

to date

Initial

development/

qualification

First

contract

ENIQ-qualification

for EDF

GENSIP

Blind Trials

Initial

development/qualification

for stainless steel welds

Initial

development/qualification

single-sided access

(ferritic)

Qualification

for Ineos O&P

Milestones

The Need for NDT Qualification

1. Outwith code criteria: e.g. dimensions; material; shape

2. Innovative NDT technology

3. Codes and qualification processes not fit for purpose

4. High level of reliability needed……

ENIQ:

“Qualification should be considered where the safety or economic consequences of possibly poor NDT performance,

and/or the difficulty of applying the NDT, are such that additional assurance is desirable that the NDT can meet the

requirements. Qualification should also be considered when a novel NDT technique is proposed.”

Qualification Methodology

Qualification of an inspection may require assessment of the NDT

system, composed of any combination of NDT procedure, equipment

and personnel.

This qualification or assessment can be considered as the sum of the

following items:

1. Technical justification, which involves assembling all evidence on the

effectiveness of the inspection, including previous experience of its

application, laboratory studies, mathematical modelling, physical reasoning

etc.

2. Practical trials (blind or open) conducted on simplified or representative

testpieces resembling the component to be inspected

Primary Application for DB - Industrial Boiler Tubes

Eg 350°C, 200 bar

11-13mm gap

63.5

mm

OD

6-7mm

37.5o

Original SBPAUT technique (2010)

DB/RWE npower collaborative development

Linear array swept beam 35o – 80o

10 MHz

Focused in active direction

Probe housing + scanner height <11mm

Semi-auto encoded

Single circumferential pass both sides of weld

Pumped couplant (water)

Scope of Initial Qualification Tube butt welds 4-9mm thick

Theoretical coverage modelling

Comprehensive practical trials Range of representative samples containing about 70 real defects

Live qualification dossier

Endorsed by UK insurers

LORF 17mm long

x no measurable height TOE CRACK

17mm long x 4.1mm

Technique capability 3.9mm

3.1mm

2.8mm

Example of permanent record

6dB drop off sizing for smooth planar defects

Maximum amplitude sizing for echodynamic pattern 1 3 and 4 defect responses

Highly accurate throughwall positioning and sizing

Qualification data

Wormhole Isolated pore

Lack of root fusion

Group porosity

Root crack Porosity

Ability to characterise all types of defect

Qualification for EDF

Characteristics of the component:

V type butt welds, straight, prep angle 30 or 37.5 deg

2 material groups : non alloyed ferritic steel or slightly

alloyed and highly alloyed

Diameters from 21mm to 80mm

Thickness from 2.8mm to 9mm

Basis of Qualification

Qualification process : see FD CEN/TR 14748 norm / meet requirement

of AM mars 1978 (French law)

Qualification based on trials on mock-ups and technical justification

Open trials on DB mock-ups and blind trials on EDF mock-ups

Techniques Developed

Sectorial scan : T35 to T80 deg

To cover the weld body and the HAZ

Linear scan : T54 or T60 deg

Depending on the angle of the weld prep.

This technique is to cover the fusion face

EDF Mock-Ups

3 Mock ups with

artificial defects

17 Mock ups with a

large number of real

defects

20 mock-ups with

various diameters,

thickness and materials

EDF Trials

Trials in Renfrew (Doosan mock ups) :

3 mock ups with two or three defects each

(mainly EDM slots, planar defect)

17 mock ups with two or three defects each (real

defect, mainly volumetric)

Trials in le Havre (EDF mock ups) :

2 mock ups with 5 defects each

(EDM slots, planar defects)

18 welds on blind trial

(real defects)

Trials Results

Over 52 Tests performed with 40 tests for

detection on mock ups and others to assess some

influential parameters (impact of the weld,

misalignment of the tubes, etc…) .

EDF Qualification

TJ contains three main parts:

Reasoning (Ermolov calculation, coverage modelling, etc…)

Simulation (CIVA modelling of planar and volumetric defects)

Practical trials results

Conclusions of the Qualification:

It has been shown that pores of unacceptable size (i.e. diameter greater than T/3) will be detected.

Calculations confirm that planar defects with an area greater than 1.5mm² will be detected. This is

supported by the results of the simulation for defects of length 5mm and height 0.5mm (i.e. area

2.5mm²).

Detection and characterisation of the defects sought can be achieved with the ultrasonic techniques

and equipment applied. The system has been qualified by EDF (France) to inspect small bore

tubing

GENSIP SBPAUT Blind Trials 2013

Detection of rejectable flaws (%)

Doosan

Babcock

Radiography

Q

ualit

y o

f siz

ing

& c

hara

cte

risa

tion

(%

) GENSIP

Generators’ Safety Improvement Programme - forum for the main UK utilities + CLP

• Conducted a blind trial of NDT vendors offering SBPAUT

• 10 participants

• 50 representative tube samples; 10 flaw types; 90 flaws

RESULTS

• DB best overall performance

• DB performed highly on planar defects

• GENSIP feedback has enabled technique refinement

• Radiography performed well on volumetric defects but poorly

on planar defects

Stainless steel welds (2-sided coverage)

25mm

7mm

Headlines from SBPAUT SS weld TJ

Detection of the following defects is highly reliable:

Lack of fusion

Lack of root penetration

Excess root penetration

Centre line crack

Toe crack

Root crack

Wormhole (≥ 10mm × 1mm)

Root concavity

Detection of the following defects is less reliable:

Tungsten inclusion

Wormhole (≤ 3mm × 0.3mm)

Porosity

Ferritic Welds – single-sided coverage

Capability statement based on the usual ENIQ qualification

elements

Included blind trials

Issue with misalignment

Headlines from SBPAUT for single side ferritic welds TJ

Planar flaws as listed in BS EN 5817 will be reported as out with the acceptance level when

the procedure is applied.

Isolated pores, wormholes and elongated cavities can be detected if larger than 1mm in

diameter. 1mm is larger than the acceptance level for pipe wall thicknesses<5mm.

Where pipe misalignment exceeds the acceptance levels of BS EN 5817 the single sided

access inspection procedure is not applicable for defects located at the weld root. .

Reference List Site Date Components Competent Body

Erraring PS (in Renfrew factory) 2011 Economiser & reheater; 4-7mm Parsons Brinkerhoff

Eggborough PS 2012 Economiser; 4-5mm RSA

Kilroot PS 2012 12Cr 2dy S/H; 7mm RSA

Longannet PS 2012 Economiser; sootblower S/H transitions; partition; quorls; 3-8mm BV

Lethabo PS (South Africa) 2012 Economiser & reheater; 3-7mm -

Eggborough PS 2013 Economiser; 4-5mm RSA

Longannet PS 2013 Economiser; sootblower S/H transitions; partition; quorls 3-8mm BV

Gardanne Biomass PS (France) 2014 Waterwall; 3 & 5mm Apave

Eggborough PS 2014 Reheater tubes RSA

Gardanne Biomass PS (France) 2015 Waterwall; 3 & 5mm Apave

Eggborough PS 2015 Reheater tubes RSA

Ineos Grangemouth 2015-16 Ethane line 4” sch 40 (6mm t) 304 ss IMechE

Shoreham CCGT 2015 Economiser 38mm dia x 3mm thick c.s. BV

Shoreham CCGT 2016 Economiser 38mm dia x 3mm thick c.s. BV

Temelin NPP, Czech Republic 2016 Range of tubes and materials (cs & ss) UJV

Hunterston NPP 2016 Range of tubes and materials (cs & ss) EDF

Taweelah B CCGT, Abu Dhabi 2016 Waterwall tubes 2½” x 7mm thick cs -

Bazan Oil Refinery, Israel 2016 Boiler tubes -

Shoreham 2017 Economiser 38mm dia x 3mm thick c.s. BV

Taweelah B CCGT, Abu Dhabi 2017 Waterwall tubes 2½” x 7mm thick cs

Shell St Fergus 2017-18 Backhaul pipework; range of tubes and materials (cs & ss) Shell TA

Shell Pearl, Ras Laffan, Qatar 2017 QSGTL SEC recovery project; coil welds 3” & 5” cs Shell TA

Tata Steel, Port Talbot 2017-18 44 bar coil steam pipework, 4” cs -

Taweelah B CCGT, Abu Dhabi 2018 Waterwall tubes 2½” x 7mm thick cs

Puteri Nilam, Malaysia 2018 Fuel oil lines and burner tubes 1”-3” cs Lloyds Register

Puteri Delima 2018 Fuel oil lines and burner tubes 1”-3” cs Lloyds Register

Slough Biomass PSS 2018 Superheater & Reheater elements 5-7” cs

ExxonMobil Mossmorran 2019 Furnace membrane tubes, 4mm x 57mm OD

Black Point PS, Hong Kong 2019 Evaporator return bends

• Around 15,000 tube butt welds inspected

Case studies

• Production Benefits

• Outage or manufacturing programmes improved by multiple

days

• Cost and programme savings are considerable

• Improved weld quality (repair rate <1%)

Further Development

• One-sided access (stainless steel welds)

• Stub-header welds

Conclusions

The Doosan Babcock SBPAUT system is robustly qualified (via extensive open trials/blind trials/theoretical

modelling/physical reasoning/on-site experience)

This evidence provides ample technical justification for replacing radiography

Significant cost and schedule savings have been realised by replacing radiography with SBPAUT

Radiography, although code compliant, does not require the same level of qualification. In fact, there is tacit

acceptance that it is unreliable for the detection of planar defects

There is a need for tailored PAUT acceptance criteria

Thank you