Transcript
Omni Om niSc Scan an SX \ MX MX2 2 Trai Traini ning ng Prog Program ram Phased Array Wedges Chris Magruder
V4.1B2T9
OmniSc OmniScan an SX \ MX2 Train Training ing – Phased Phased Array Array Wedge Wedges s Overv Overview iew
Phased array wedges perform the same function as conventional UT wedges by coupling sound energy from the probe to the material at the desired refracted angle and wave type. Phased array wedges come in all shapes and sizes for various applications and are an essential part of the inspection process. Phased array wedges are used to assist the probe in beam formation for shear wave and longitudinal wave inspections, just like UT. 1D Wedges typically used in OmniScan MX2 applications come in 3 varieties: 1. Shea Shearr wa wave an angl gle eb be eam 2. Lo Long ngit itud udin inal al wa wave ve an angl gle e be beam am 3. Lo Long ngit itud udin inal al wa wave ve stra straig ight ht be beam am
OmniSc OmniScan an SX \ MX2 Train Training ing – Phased Phased Array Array Wedge Wedges s Overv Overview iew
Phased array wedges perform the same function as conventional UT wedges by coupling sound energy from the probe to the material at the desired refracted angle and wave type. Phased array wedges come in all shapes and sizes for various applications and are an essential part of the inspection process. Phased array wedges are used to assist the probe in beam formation for shear wave and longitudinal wave inspections, just like UT. 1D Wedges typically used in OmniScan MX2 applications come in 3 varieties: 1. Shea Shearr wa wave an angl gle eb be eam 2. Lo Long ngit itud udin inal al wa wave ve an angl gle e be beam am 3. Lo Long ngit itud udin inal al wa wave ve stra straig ight ht be beam am
OmniSc OmniScan an SX \ MX2 Traini Training ng – Phased Phased Array Array Wedges Wedges Over Overvie view w cont. cont.
Wedges can be optimized for manual hand inspection, automated scanner inspection, or special applications. Wedge features available include: – – – – – – – –
Carbide feet for protection from from wear. Built-in irrigation ports and channels. channels. Scanner and encoder encoder attachments points. Inner and outer component component radius curvature. Water channels on base base of wedge. Stainless steel scanner guides. guides. Multiple positions for for the probe. And more….
OmniScan SX \ MX2 Training – Phased Array Wedges - Rexolite
Rexolite is a rigid and transparent plastic produced by cross linking polystyrene with divinylbenzene. Rexolite is an isotropic material that has a constant velocity in each axis of 2330 meters/sec and impedance similar to water. Rexolite has an outstanding dielectric constant of 2.5MHz to up to 500 GHz with an extremely low dissipation factor making it well suited for advanced NDT, sonar lenses, sonic medical systems, missile guidance systems, microwave circuitry and many other ultrasonic and optical applications. (Does not filter the bandwidth) Rexolite exhibits no permanent deformation under loads up to 2000 psi and at temperatures between 20-125 degrees Celsius. (257 degrees Fahrenheit) Rexolite can be machined with tolerances much tighter than Lucite or low grade plastics. For these reasons Rexolite is an ideal material for phased array wedge manufacturing.
OmniScan SX \ MX2 Training – Olympus Wedge Definition
The complete definition for wedges is available in the current Olympus probe catalog and below. The part number is divided into 4 sections and may or may not contain the last two.
OmniScan SX \ MX2 Training – Olympus Wedge Housing
Olympus wedges are manufactured to be compatible with the same family of housing. Typical housing numbers are A2, A10, A12, etc. and are printed on the probe and wedge and referenced in the catalog.
Any probe and wedge of the same housing family are compatible. In the SA12 example below there are wedge options for shear wave angle beam, longitudinal wave angle beam, and longitudinal straight beam.
OmniScan SX \ MX2 Training – Olympus Wedge Housing cont.
Some housing types can accommodate probe models of different pitch size and frequency, and may not be symmetrical in the housing. Wedges compatible with these types of probes contain separate probe position options with separate attachment points including reversing the probe. Care should be taken to ensure the correct probe, wedge, position are selected from the wedge database.
5L64 Position
2L64 Position
A27probe and wedge
OmniScan SX \ MX2 Training – Wedge Carbide Wear Pins
Use of carbide wear pins on the wedges is common for auto and semi-auto inspections where high production or repetitive scanning is required. The wear pins provide both protection from wear on the wedge, and stability for improved performance and repeatability. Wear pins should be secured in place with “Lock-tight” and require a constant water supply through the water ports. UT couplant gel is not recommended. Use of carbide wear pins directly affects wedge delay and sensitivity calibration. Failure to complete the calibration process with the same couplant technique and pin position as the inspection will result in a reduction of precision measurement and repeatability.
OmniScan SX \ MX2 Training – Wedge Refracted Angle
Included in the wedge label after the housing family (SA10, SA12, etc) is the nominal refracted angle (N60S) in steel with no beam steering. To achieve a shear wave refracted angle of 60 degrees (N60S) in steel the wedge is cut with an incident angle of 39 degrees in Rexolite. (Snell’s law) N55 and N60 are common wedge designs because this angle allows good beam steering from approximately 30-70 degrees for most probes\wedge combinations.
39 degrees in Rexolite
60 degrees in carbon steel
OmniScan SX \ MX2 Training – 0L Straight Beam Wedge
A zero degree wedge is designed for both straight beam and angle beam longitudinal wave inspection as is typically used in corrosion mapping or composite lamination type inspections. This type of wedge acts as a stand off delay and provides improved near surface resolution compared to using a probe with no wedge. The 0L wedge also protects the probe as scanning with no wedge exposes the probe membrane to wear and damage.
OmniScan SX \ MX2 Training – Wedge Curvature Definition Overview
Wedge coupling is essential for a good inspection and where the wedge is too large to properly mate against the material, sound is impeded and the wedge must be contoured. The 3 most common types of wedge curvature for optimization of a particular component, pipe or vessel inspection are: 1. Flat 2. AOD## (Axial Outside Diameter Curvature + Diameter) 3. COD## (Circumferential Outside Curvature + Diameter)
OmniScan SX \ MX2 Training – Wedge Curvature Definition Overview
Other custom wedge configurations are available on request as well as wedges machined to a particular component like a dove tail joint.
OmniScan SX \ MX2 Training – AOD Wedges
AOD wedges are contoured for the pipe diameter for typical girth weld inspections in the axial axis. Depending on the footprint of the wedge and pipe diameter, a flat probe may be sufficient for the inspection eliminating the need for an AOD contour. The phased array calculator need not differentiate between flat and AOD wedges because the probe element position (Height from bottom) is the same for both. For this reason, separate entries for AOD wedges do not appear in the OmniScan SX\MX2 database. In the Olympus probe catalog you will find a reference for the curvature limits for common wedges based on housing type and nominal pipe diameter.
OmniScan SX \ MX2 Training – COD Wedges
Inspection in the circumferential axis or “Long seam” type inspection requires a COD wedge and special hardware and software considerations. COD wedges are calibrated at the factory for precise incident angle to be used in the focal law calculator. Each wedge is treated independently for precision. The COD inspection for the OmniScan MX2 requires that the focal laws be built externally with a computer based calculator like Tomoview and imported into the OmniScan MX2 for use.
OmniScan SX \ MX2 Training – Integrated Wedges
Wedges can be integrated directly into the probe or custom built for specialized scanners and mechanics. Integrated wedges are used for angle beam and straight beam inspection. The phased array calculator requires the same independent information for the wedge parameters in relationship to the probe.
OmniScan SX \ MX2 Training – Special Application Wedges - Rexoform
The Olympus Rexoform system uses a specialized 0 degree longitudinal wedge for corrosion mapping applications. The Rexoform wedge has an integrated mechanical support that is designed to adapt to different pipe diameters eliminating the rocking effect and minimize the need for a contoured wedge.
OmniScan SX \ MX2 Training – Special Application Wedges - Hydroform
The Hydroform corrosion mapper is a form of a specialized phased array probe and wedge using water as the coupling medium. It uses a stable water column with an adjustable probe height to transmit sound into the component for corrosion inspection and C-scan generation. The Hydroform wedge parameters for the phased array calculator are selected directly from the database in the SX\MX2 software and use the velocity of water. The benefits of using water as the wedge include improved component coupling and improved near surface defect resolution.
OmniScan SX \ MX2 Training – Composite Radii Wedge Solution
The Olympus Radii solution is a immersion corner wedge for curved linear array probes. Allows for internal and external radius inspection and adjustment of different wedge height and radius size. Wedge parameters are entered into the calculator for correct beam formation.
OmniScan SX \ MX2 Training – Custom Contours
In this example the phased array wedge was manufactured to the same taper as the component for a perfect fit. Custom wedges than cannot easily be defined by the phased array calculator have inherent limitations. The ability to calibrate wedge delay and sensitivity requires a custom calibration block and precision beam steering and focusing is reduced. The inspection below is for cracks using an amplitude C-scan and metal loss using a position or “Time of flight” C-scan.
Position
C-scan
Amplitude C-scan
OmniScan SX \ MX2 Training – Special Application Wedges - Aqualene
Aqualene is an elastomer designed specifically for ultrasonic inspection applications. Acoustic impedance is nearly the same as water and its attenuation coefficient is lower than many documented plastics. Aqualene couplant reduces the drawbacks of wet coupling when used on porous refractory surfaces and acts as a thermal insulator. Aqualene couplant products are available in many sizes and thicknesses including custom design specifications. Benefit for customer phased array applications include: – Flexible couplant pads and minimal water addition. – Low velocity delay lines. – Water box coupling system membranes.
OmniScan SX \ MX2 Training – Wedge Selection in the OmniScan SX\MX2
In the OmniScan SX\MX2 software the wedge selection and management can be accessed from two locations: 1. Setup wizard. 2. Probe and wedge sub menu.
Wedges are selected from the database. New or custom wedges can be created and stored. One wedge may have many entries based on probe position, orientation, and different probe model within the same type of housing. (SA1, SA2, etc.) Care should be taken when selecting the wedge model in the software. It is a common source of problems including angle error, wedge delay error, and improper beam formation.
OmniScan SX \ MX2 Training – Wedge Specification Data Sheet
Every wedge from Olympus is delivered with a wedge specification data sheet that contains all of the parameter values to populate the OmniScan MX2 database or external focal law calculator. These values are relative to the probe and its orientation on the wedge. For that reason one wedge may be listed many times in the database.
OmniScan SX \ MX2 Training – Wedge Database Update on the Web
New wedges are added to the database periodically at different intervals than the software updates. At any time the current wedge database can be directly updated on the OmniScan MX2 memory card by downloading a utility from the software support section of the Olympus web page at www.olympus-ims.com
OmniScan SX \ MX2 Training – Phased Array Wedge Parameters Overview
The following parameters are required for the OmniScan MX2 wedge database and phased array calculator: – – – – –
Wedge model. Wedge angle. Wedge orientation. (Normal or reverse) Height of element #1 of the probe (h1). Wedge material velocity. (2330m/s Rexolite) – Primary and secondary offsets (x,y).
OmniScan SX \ MX2 Training – Phased Array Wedge Parameters - Angle
Question: What is the affect on the UT data if the wedge angle is different than the calculator (Wizard) input? Answer: The beam formation is incorrect resulting in angle, focusing, and delay errors that cannot be overcome in the calibration process. Minor angle errors due to machining tolerances are the same as conventional UT wedges and typically need not be corrected with precision measurement on specific wedge serial number.
OmniScan SX \ MX2 Training – Phased Array Wedge Parameters - Angle
Question: Can the angle of the wedge be measured if it is unknown?
Answer: Yes. It can be measured mechanically and ultrasonically. If it is different than the database or more precision is required it can be entered as a new or custom wedge. The procedure for measuring the wedge angle ultrasonically is covered in the acoustic validation section.
OmniScan SX \ MX2 Training – Phased Array Wedge Parameters - Orientation
Due to the scanner limitation or inspection access it is sometimes necessary to reverse the orientation of the probe elements to accommodate the probe cable. This is a function of the wedge orientation and it is defined as either normal or reverse. Selecting reverse will have the affect of reversing the probe element wiring. (1-64 changes to 64-1)
OmniScan SX \ MX2 Training – Wedge Parameters – Height of Element 1
Question: What is the affect on the UT data if the height of the first element is different than the calculator (Wizard) input?
Answer: The wedge delay of the beam is not calculated correctly resulting in depth reading errors. The selected focus distance in the material is short or long based on the error. Angle is not affected. Wedge delay can be corrected in the calibration wizard.
OmniScan SX \ MX2 Training – Wedge Parameters – Height of Element 1
Question: Does normal usage result in wedge wear that will change the height of the first element?
Answer: Yes. This can be corrected in the wedge delay calibration wizard or created in the wedge database as specific serial numbered wedge. This is normal and can be minimized with use of carbide wear pins on the wedge. Unlike probes, wedges in some environments are consumables.
OmniScan SX \ MX2 Training – Phased Array Wedge Parameters - Height
Question: Can the height of the first element on the wedge be measured if it is unknown?
Answer: Only ultrasonically, not mechanically. This is done by using the fixed velocity of the wedge as the component. (Inspecting the wedge) This process is covered in a later section. It cannot be measured mechanically because element #1 is hidden behind the membrane in the probe housing and it is impossible to know the exact position to measure.
OmniScan SX \ MX2 Training – Phased Array Wedge Parameters - Velocity
The velocity of the wedge must be known prior to formation of the focal laws. It cannot be measured or corrected during the calibration process. Most wedges from Olympus that are designed to be used with the OmniScan MX2 are made of Rexolite. Rexolite is an isotropic material that has a constant velocity in each axis of 2330 +\- 20 meters\sec Wedge velocity like component velocity is directly related to the incident and refracted angles and is an essential variable in the calculator. (Snell’s Law). Temperature affects velocity and similarly to conventional UT the calibration must be performed near the same wedge and component temperature as the inspection.
OmniScan SX \ MX2 Training – Wedge Parameters - Offsets
Offsets are the relationship of probe element #1 to the side and front of the wedge. As pictured right, X is the primary offset and Y is the secondary offset and is normally 0mm. The element #1 position is normally referenced from the front of the wedge face and for that reason the number is negative. (-69mm below)
OmniScan SX \ MX2 Training – Wedge Parameters - Offsets
Question: What is the affect on the UT data if the primary offset is wrong?
Answer: The beam exit point is miscalculated by the software and the surface distance to the indication is incorrect. The offsets are only for determining position and do not affect beam formation. The A-scan appears normal, trigonometry and depth readings are normal, and only the rulers, weld overlay, and skip lines are wrong.
OmniScan SX \ MX2 Training – Phased Array Wedge Parameters - Offsets
Question: Is it possible to know the primary offset of element #1 by measuring it on the probe and wedge?
Answer: No. The probe elements are not visible through the protective membrane and the position of element #1 cannot be measured with precision. The offset position must come from the drawing of the probe married to the wedge. Close approximations are unacceptable and result in reduced precision.
OmniScan SX \ MX2 Training – Phased Array Wedge Review
What are the essential parameters of 1D linear array wedge that are required by the OmniScan SX\MX2 software? 1. Wedge model number. 2. Wedge orientation. 3. Height of element #1 on probe. 4. Wedge velocity. 5. Wedge offsets.
OmniScan SX \ MX2 Training – Phased Array Focal Law Calculator Review
What are the essential parameters for the phased array calculator? 1. Probe parameters. 2. Wedge parameters. 3. Material Velocity 4. Beam Formation.