Radiography (RT) uses transmission of ionizing radiation through matter. Two methods are distinguished here, according to the type of wave emission source:

• X-ray testing (using vacuum tubes);
• Gamma ray (γ) testing (using radioactive isotopes; we use Se75 and Ir192 at our laboratory).
   

X rays and γ rays penetrate the material where they attenuate and disperse. For a specific X ray and γ ray wavelength, attenuation depends on the type and thickness of scanned material. This process is the basis of detection of defects in material. If the radiation beam encounters an item such as a metal plate of a certain thickness, it will attenuate, the attenuation will be lower where the beam strikes a layer of metal with a void inside, and the intensity of the output beam will be higher. If a photographic plate is positioned under the tested plate, it will be blackened by the radiation. The blackening, i.e. optical density, is proportional to the output radiation intensity logarithm, meaning that it will be stronger at the location of the defect.

Radiographic tests are volumetric. A single radiograph can be used to identify the type of an internal defect and its position in parallel to the photographic plate. However, the depth of the defect cannot be determined on this basis. Material defects visible on a radiograph are assessed according to strictly defined criteria.

We carry out the radiographic tests according to the guidelines of PN-EN ISO, ASME, DNV, AD 2000 MERKBLAT, using X-ray tubes and radioactive isotopes Se75 and Ir192.

Radiographic testing is performed in conformity with the following standards:

PN-EN 1330-3:1999 - Non-destructive testing. Terminology Terms used in industrial radiographic testing

PN-EN ISO 17636-1:2023-02 - Non-destructive testing of welds — Radiographic testing — Part 1: X- and gamma-ray techniques with film

PN-EN ISO 10675-1:2022-05 - Non-destructive testing of welds — Acceptance levels for radiographic testing — Part 1: Steel, nickel, titanium and their alloys

PN-EN ISO 10675-2:2022-05 - Non-destructive testing of welds — Acceptance levels for radiographic testing — Part 2: Aluminium and its alloys

PN-EN ISO 5579:2014-02 - Non-destructive testing — Radiographic testing of metallic materials using film and X- or gamma rays — Basic rules

PN-EN ISO 19232-1:2013-08 - Non-destructive testing — Image quality of radiographs — Part 1: Determination of the image quality value using wire-type image quality indicators

PN-EN ISO 19232-2:2013-10 - Non-destructive testing — Image quality of radiographs — Part 2: Determination of the image quality value using step/hole-type image quality indicators

PN-EN ISO 19232-3:2013-10 - Non-destructive testing — Image quality of radiographs — Part 3: Image quality classes

PN-EN ISO 19232-4:2013-10 - Non-destructive testing — Image quality of radiographs — Part 4: Experimental evaluation of image quality values and image quality tables

PN-EN ISO 19232-5:2018-10 -  Non-destructive testing — Image quality of radiographs — Part 5: Determination of the image unsharpness and basic spatial resolution value using duplex wire-type image quality indicators

PN-EN ISO 11699-1:2012 - Non-destructive testing — Industrial radiographic film — Part 1: Classification of film systems for industrial radiography

PN-EN ISO 11699-2:2018-10 - Non-destructive testing — Industrial radiographic films — Part 2: Control of film processing by means of reference values

PN-EN 25580:1997 - Non-destructive testing; industrial radiographic illuminators; minimum requirements

PN-EN 12681-1:2018-01 - Founding. Radiographic testing. Film techniques

PN-EN 12681-2:2017-12 - Founding. Radiographic testing. Techniques with digital detectors

PN-ISO 9915:1998 - Aluminium alloy castings — Radiography testing

PN-EN ISO 10893-6:2019-04 - Non-destructive testing of steel tubes — Part 6: Radiographic testing of the weld seam of welded steel tubes for the detection of imperfections

• Category Title

Ultrasonic thickness measurements are used to assess the service condition of operated structures and equipment subject to technical inspection through monitoring the consequences of corrosion and erosion, material wear, or random damage. In view of the quantity of aging operating facilities and the need to ensure their safe operation, examination of wall thinning is a fundamental diagnostic feature.

Ultrasonic techniques applied

Spot measurements of wall thickness

Ultrasound wall thickness measurements are taken at measuring grid points defined by the supervisory authorities or the terms of the applicable standards. In this technique, the layout of points should be such that minimum wall thickness locations can be detected. The measurements are used to determine the minimum, maximum and average wall thickness. This technique is recommended when the tested piece underwent general corrosion or erosion, i.e. when the corrosion losses are distributed evenly or the thinning of the wall is uniform across the entire surface. The level of wear of the inspected item is determined on the basis of averaged test results. This technique is not recommended when localized pitting corrosion is present in the material because in such case, the deepest pits may be located in between the measuring grid points, which may be the reason of wrong assessment of the actual wear of the inspected equipment item or structure.

Corrosion mapping

Corrosion mapping with the use of advanced Phase Array ultrasonic testing technique offers measurement of wall thickness of plant and equipment with a complete record of results which are then represented as a map of defects within the scanned area, the outcome being much more accurate than in the case of localized measurements.

We perform our corrosion mapping jobs with OMNIX3-PATFM32128PR-KIT with the Hydroform -K-Manual Scanner kit.

TOFD (Time of Flight Diffraction)
PA (Phased Array)

Automation of welding systems is among the main drivers of development of contemporary non-destructive testing, as a prerequisite for increasing the work rate and output while at the same time improving the efficiency and defect detection precision. These technologies are mainly used in the nuclear energy industry, construction of long-distance pipelines, vessels or steel structures in the refining industry.

The TOFD (Time-Of-Flight Diffraction) method uses diffraction of ultrasonic waves. The test records ultrasonic wave pulses distributed on the edges of material defects. The basis of the measuring system are two broadband longitudinal wave angle beam probes positioned at a fixed distance from each other. One of the probes is a transmitter and the other one is a receiver. Defects are located on the basis of the time of flight of the ultrasonic wave, while defect size is measured on the basis of the differences of the time of flight from one edge of the defect to another.

Advantages of the TOFD method:

Very high limit of detection for planar discontinuities;
Precise location of material defect (significantly higher accuracy than that of the pulse-echo method);
High testing resolution with reading data in the range of 0.1 mm;
High reliability of test results.
 

The PA (Phased Array) method is an extension of the traditional pulse-echo ultrasound testing. Multiple transducers in an array inside the testing probe are used in the PA method for controlling the ultrasonic beam so as to obtain an image similar to a radiography image. Compared to conventional techniques, PA tests are faster, more reliable, with a higher resolution and sensitivity, which improves the test quality.

TOFD and PA tests are carried out with Olympus OMNISCAN X3.

Digital ultrasonic testing is performed in conformity with the following standards:

PN-EN ISO 10863:2020-12 - Non-destructive testing of welds — Ultrasonic testing — Use of time-of-flight diffraction technique (TOFD)

PN-EN ISO 15626:2018-10 - Non-destructive testing of welds — Time-of-flight diffraction technique (TOFD) — Acceptance levels

PN-EN ISO 13588:2019-04 -  Non-destructive testing of welds — Ultrasonic testing — Use of automated phased array technology

PN-EN ISO 19285:2017-11 - Non-destructive testing of welds — Phased array ultrasonic testing (PAUT) — Acceptance levels

• Category Title

Ultrasonic tests (UT) are volumetric tests, perfectly detecting planar discontinuities, i.e. porosity, as well as welding defects such as lack of fusion, incomplete fusion, cracks.

Our service range includes:

• Conventional ultrasonic testing as per PN-EN ISO 17640:2019-01;
• Digital ultrasonic techniques: TOFD (Time of Flight Diffraction) and PA (Phased Array);
• IBUS weld testing procedure;
• Density measurement as per PN-EN ISO 16809:2019-08.

All sounds with a vibration frequency above the upper audible limit of human hearing (16000÷18000 Hz) are called ultrasounds. Ultrasounds are produced with electro-acoustic transducers based on piezoelectricity and magnetostriction. The transducers transform acoustic energy into electricity and vice versa. Ultrasound waves are characterized in that they do not propagate in vacuum, while they propagate very well in metals, they are capable of covering relatively large distances without major energy losses (up to several meters in steel), diffracting on the border of two media with different physical properties and elasticity, easily converging to beams, which facilitates detection of minor defects.

Three types of ultrasonic methods can be distinguished:

Transmission method - observing the attenuation of ultrasonic wave energy, using the fact that the type and location of a defect has a major effect on the weakening of the transmitted energy. In this method, two transducers are positioned on the opposite sides of the inspected specimen, of which one is the transmitter and the other one the receiver;
Pulse-echo method - in this method, the transmitter and the receiver are positioned on the same side of the inspected piece. Two pulses (input and output) are generated for a good specimen, whereas an additional third signal (flaw echo) appears for a defective weld. Based on the distance between the pulses, the depth of the material defect is determined;
Resonance method - mainly used to measure thickness of thin-walled specimens. It consists of observation of the formation of a standing wave maximum or recording the vibration frequency at which such maximums occur.

Ultrasonic tests are mainly used to:

• Detect material discontinuities (testing of welds, casts, forgings and metal sheets for delamination);
• Measure thickness of pieces accessible from one side only (boilers, vessels);
• Structure testing.
   

We carry out ultrasonic testing using ultrasonic defectoscopes:

• Olympus EPOCH600
• Olympus EPOCH650
• Krautkramer USM35XS
   

Ultrasonic testing is performed in conformity with the following standards:

PN-EN ISO 5577:2017-04 - Non-destructive testing — Ultrasonic testing — Vocabulary

PN-EN ISO 17640:2019-01- Non-destructive testing of welds — Ultrasonic testing — Techniques, testing levels, and assessment

PN-EN ISO 11666:2018-04 - Non-destructive testing of welds — Ultrasonic testing — Acceptance levels

PN-EN ISO 10863:2020-12 -  Non-destructive testing of welds — Ultrasonic testing — Use of time-of-flight diffraction technique (TOFD)

PN-EN ISO 15626:2018-10 -Non-destructive testing of welds — Time-of-flight diffraction technique (TOFD) — Acceptance levels

PN-EN ISO 13588:2019-04 - Non-destructive testing of welds — Ultrasonic testing — Use of automated phased array technology

PN-EN ISO 19285:2017-11 - Non-destructive testing of welds — Phased array ultrasonic testing (PAUT) — Acceptance levels

PN-EN ISO 16809:2019-08 - Non-destructive testing. Ultrasonic thickness measurement

PN-EN ISO 16810:2014-06 - Non-destructive testing — Ultrasonic testing — General principles

PN-EN ISO 16811:2014-06 - Non-destructive testing — Ultrasonic testing — Sensitivity and range setting

PN-EN ISO 23279:2017-11 - Non-destructive testing of welds — Ultrasonic testing — Characterization of discontinuities in welds

PN-EN ISO 16823:2014-06 -  Non-destructive testing — Ultrasonic testing — Transmission technique

PN-EN ISO 16826:2014-06 - Non-destructive testing — Ultrasonic testing — Examination for discontinuities perpendicular to the surface

PN-EN ISO 16827:2014-06 -  Non-destructive testing — Ultrasonic testing — Characterization and sizing of discontinuities

PN-EN ISO 2400:2013-03 - Non-destructive testing — Ultrasonic testing — Specification for calibration block No. 1

PN-EN ISO 7963:2023-05 - Non-destructive testing — Ultrasonic testing — Specification for calibration block No. 2

PN-EN 10160:2001 - Ultrasonic testing of steel flat products of thickness equal or greater than 6 mm (reflection method)

PN-EN ISO 22232-3:2021-03 - Non-destructive testing — Characterization and verification of ultrasonic test equipment — Part 3: Combined equipment

PN-EN ISO 22232-2:2021-03 - Non-destructive testing — Characterization and verification of ultrasonic test equipment — Part 2: Probes

PN-EN 10228-3:2016-07 - Non-destructive testing of steel forgings - Part 3: Ultrasonic testing of ferritic or martensitic steel forgings

PN-EN ISO 10893-8:2011 - Non-destructive testing of steel tubes — Part 8: Automated ultrasonic testing of seamless and welded steel tubes for the detection of laminar imperfections

PN-EN ISO 10893-8:2011/A1:2020-12 - Non-destructive testing of steel tubes — Part 8: Automated ultrasonic testing of seamless and welded steel tubes for the detection of laminar imperfections

PN-EN ISO 10893-10:2011/A1:2021-01 - Non-destructive testing of steel tubes — Part 10: Automated full peripheral ultrasonic testing of seamless and welded (except submerged arc-welded) steel tubes for the detection of longitudinal and/or transverse imperfections