What is a flat bottom hole?

What is a flat bottom hole?

The Flat-bottom Hole (FBH) is machined to have a flat reflecting surface at the hole bottom. The hole bottom is typically parallel to the beam entry surface, but can be machined at other desired angles. FBHs can be machined just about anywhere they are needed for a particular inspection.

What is flat bottom hole in ultrasonic testing?

SDH – Side-Drilled Hole and FBH – Flat-Bottomed Hole are the two main calibration reflectors which are used in ultrasonic testing. The FBH is drilled into calibration blocks so that the flat end face presents a circular disc perpendicular to the beam (see Figure, top).

What are the purposes of reference standards blocks in NDT?

Using NDT Reference Standards Reference, or calibration standards as they are often called, are used to standardize and calibrate NDT test equipment to ensure the ability of the equipment to correctly detect the signals that the particular equipment setup and procedure are sensitive to.

How do you choose eddy current probes?

One of the most important specifications for eddy current probes is the frequency of the coil or probe transmission. This value is typically specified as the center-band frequency. Selection of frequency depends on many factors, such as material and subsurface depth of inspection interest.

What are flat bottom drill used for?

Holemaking & Threading The flat bottom of the tools in this Miniature High Performance Drills – Flat Bottom offering allows for drilling on irregular surfaces. Use this tool on inclined and rounded surfaces, or for creating flat bottom holes, angled holes, intersecting holes, half holes, shoulders, or thin plates.

What is Probe Delay in ultrasonic testing?

The rising flank corresponds to the time at which the electrical signal is on the crystal and starts the sound pulse. However, before it is fed to the surface of the test object it must travel through the protection layer of the probe (probe delay). Although it is relatively thin, a short period of time is required.

What are the different types of probes used in ultrasonic testing?

Ultrasonic probes

  • Angle Beam Probes (single element)
  • Angle Beam Probe (single element)
  • Straight Beam Probes (double element)
  • Straight Beam Probes with replaceable membrane (dual element)
  • Straight Beam Probe with ceramic face (single element)
  • Straight Beam Probes (single element)

What is calibration block?

Calibration Block 1 (EN12223) A steel block for the calibration of ultrasonic flaw detection equipment used in material testing. Used for the calibration of shear and longitudinal transducers, determination of shear wave emission point, refracted angle. Also for measurement of sensitivity and resolution.

What are the limitations of eddy current testing?

Disadvantages: Method restricted to conductive materials. Inspection of ferromagnetic materials can be impacted by magnetic permeability. Depth of inspection (penetration) is limited.

What are the types of eddy current probes available?

Eddy current probes

  • Conductivity probe (Reflection type)
  • Right angle surface probe (Reflection type)
  • Straight surface pencil probe (Reflection type)
  • Dynamic Rotating Rigid Probe (with stainless steel housing) for bolt holes testing (coils are positioned at right angles to the probe shaft length, Differential Unshielded)

What is inside diameter eddy current inspection?

Inside-diameter (ID) eddy-current testing inspection can be performed at speeds up to six feet per second, and tubing does not need to be as clean as it does with ultrasonic and other forms of testing. Eddy-current inspection is available in two modes: differential and absolute.

What is the reference standard for eddy current testing?

The reference standard used for both OD and ID eddy-current testing should contain artificial discontinuities. These include varying depths of a flat bottom drilled holes, a through-wall drilled hole, and ID- and OD-circumferential grooves that can be demonstrated to be comparable to the defects normally found during operation.

Should ID eddy-current testing be performed prior to fabrication?

If ID eddy-current testing is performed prior to fabrication, defects developed during the shipping and installation process might be missed or ignored. Other than customers’ specific requirements, there is no single standard accept/reject criteria for ID eddy-current testing of heat exchanger tubing.

How does the depth of an eddy current change with conductivity?

There is a greater flow of eddy current at the surface in high conductivity metals and a decrease in penetration in metals such as copper and aluminium. The depth of penetration may be varied by changing the frequency of the alternation current – the lower the frequency, the greater depth of penetration.