More info a
Digital Profile Radiography
– Practical uses and limitations
Mr. Neil Young
Asset Reliability Inspections
Bunbury, Australia
www.ari.com.au
neil.young@ari.com.au
Introduction
Profile digital radiography for online
piping thinning assessment has been
in use in Australia since 2005 and
recently is gaining significantly more
acceptance/use.
Today all major refineries in Australia
use digital imaging for pipe inspection.
This is helped by new international
standards.
This workshop aims to explain the uses
and limitations of this technology with
some real world samples.
NDT in Canada 2017 Conferencep
Digital Radiography – What is it?
Essentially the same as conventional film radiography with the
exception that the image is captured via reusable digital media instead
of film, at a lower radiation dose by either a Digital Detectors Array
(DDA) panel or on a Phosphor Imaging Plate (PIP or IP).
Industry separates the two mediums by calling DDA – Digital
Radiography (DR) and IP – Computed Radiography (CR).
NDT in Canada 2017 Conference
Advantages / Disadvantages
• Instant results (DDA) – no reshoots • High initial capital costs
• Fast results (CR) – easy onsite processing • Restricted to smaller size pipes
• Software for wall thickness evaluation • Additional training
• Easily shared (email an image) • Radiation exclusion zones
• No chemical dark rooms • Digital, poor data in = poor data out
• Broader area (you get the bigger picture) • DDA lower spatial resolution than film
• Higher dynamic range
• Higher productivity & automated
workflows
• Ability to hunt degradation
NDT in Canada 2017 Conference
Methods of test - Standards
• BS EN 16407-1 Non-destructive testing – Radiographic inspection of
corrosion and deposits in pipes X- and gamma rays Part 1:
Tangential radiographic inspection
• BS EN 16407-2 Non-destructive testing — Radiographic inspection
of corrosion and deposits in pipes by X- and gamma rays Part 2:
Double wall radiographic inspection
NDT in Canada 2017 Conference
Pipe Size Limitations
(what is readily achievable)
You are restricted on what pipe size / schedule you can test. This
restriction is due to the different penetrating power of the radiation
type used which is referred to a Wmax in EN16407.1
(referred to as chord length in conventional Australian standards)
AOG 2017 Knowledge Forum Workshop
Standard prescribes maximum allowable thickness (Wmax)
for different types of radiation (different penetrating power)
NDT in Canada 2017 Conference
What does this equate to for two commonly used gamma sources?
Ir192 Se75
Sch40 Sch80 Sch160 Sch40 Sch80 Sch160
DN 15-65 Yes Yes Yes Yes Yes Yes
DN 80 Yes Yes Yes Yes Yes No
DN 90 Yes Yes N/A Yes Yes N/A
DN 100 Yes Yes No No No No
DN 125 Yes Yes No No No No
DN 150 Yes Yes No No No No
DN 200 No No No No No No
What does this mean?
• Using Se75 for smaller exclusion zones etc gives you less scope than Ir192
• Both sources are only useable on smaller piping
• If using battery powered pulsed X-ray units again for exclusion zones/safety
you are more restricted again than when using Se75
• Larger pipes need to be examined with ultrasonic or eddy current techniques
TIP: Fittings are thicker so if you have designed a PRT scope on the upper limits based on pipe size/schedule you will
struggle for accurate data on the fittings (elbows, Tees etc) attached to these pipes [which is typically where you are
looking with flow/direction changes]
NDT in Canada 2017 Conference
Insulation – Internal and External pipe
degradation
A key advantage of this technology is that by looking at the image you detect
internal (flow/contents) degradation and/or external corrosion (CUI)
If you detect CUI at early stages you can then address the issue/s with a
repair before costly replacements
EN16407-01 Standard prescribes a visual assessment of the area as well by
stati g o the test epo t the co ditio of the i sulatio
• No point in getting a satisfactory radiographic result and not being
advised of degradation of the insulation that will affect the result at
the next inspection
• With the right service provider you can get a visual examination of
the lagging and the thickness result
• Our reports detail this and include a set up image which can double
as record of condition of the recording point at time of test
NDT in Canada 2017 Conference
NDT in Canada 2017 Conference
Order of Accuracy – Set up mistakes
• Image Calibration – Test arrangement OR Reference Object
• Understand where you want to test – intrados/extrados, washout,
flow/impact
NDT in Canada 2017 Conference
Tangential Offset - E su e you a e s ua e with the wall you a e
trying to examine
Detector
Misalignment
Pipe
Misalignment
Source
Placement
La ge pipes do ’t the go easu i g the othe side
NDT in Canada 2017 Conference
Tangential Centerline - Ensure your source is central and your comparator
ball is offset to correctly capture the enlargement
(examine both sides)
NDT in Canada 2017 Conference
Reducing The Human Factor
• All previous sources of error are human and are reducible
• Ask for ISO9712 certification such as that offered by the AINDT
• Ask for specific ISO17025 accreditation offered by NATA
NDT in Canada 2017 Conference
Sample Images
Wrapped Temporary Repair Pipe Test
NDT in Canada 2017 Conference
Sample Images
Soil Air Interface – External Corrosion Blisters
NDT in Canada 2017 Conference
Sample Images
Bigger Picture
NDT in Canada 2017 Conference
Sample Images
Wire Rope Trials
NDT in Canada 2017 Conference
Software Demonstration
• Fittings are thicker
• Upper limit struggles
• Oxide separation wall thickness tool
• Holed
• Tangential offset opposite calibration side variations
NDT in Canada 2017 Conference
Fittings Are Thicker
NDT in Canada 2017 Conference
Enlargement
NDT in Canada 2017 Conference
Water Filled
NDT in Canada 2017 Conference
Oxide layer Separation
NDT in Canada 2017 Conference
Debris Trap
AOG 2017 Knowledge Forum Workshop
