بازرسی جوش به روش UT و حد پذیرش

Three types of seismic waves: 

(a) Rayleigh wave  ( Surface wave )

(b) compressional wave ( longitudinal wave )

(c) shear wave

Q30. During ultrasonic inspection (UT) on a 20 mm thick weld, an indication having length 2 mm observed, which is characterised as lack of fusion between the base metal and weld metal. As per the acceptance criteria in ASME Section VIII Division 1, this defect is: 

Not Acceptable

Acceptable

Acceptance depends upon the depth of flaw

None of above

(Explanation: According to ASME Section VIII Division 1, any indication characterized as a lack of fusion is unacceptable regardless of its size. Since the 2 mm long indication in the 20 mm thick weld has been characterized as lack of fusion, it would be unacceptable per ASME Section VIII Division 1 criteria, regardless of its size or depth

The angle at which 90° refraction of a longitudinalsound wave is reached is called the:

a. angle of incidence.

b. first critical angle.

c. angle of maximum reflection.

d. second critical angle.

When inspecting aluminum by the immersion method using water for a couplant, the following information is known: velocity of sound in water = 1.49 × 105 cm/s, velocity of longitudinal waves in aluminum = 6.32 × 105 cm/s, and angle of incidence = 5°. The angle of refraction for longitudinal waves isapproximately:

a. 22°

b. 18°

c. 26°

d. 16°

Sin5/x = 1.49 / 6.32

Beam divergence ( spread out ) is a function of the dimensions of the crystal and the wavelength of the beam transmitted through a medium, and it:

a. increases if the frequency or crystal diameter decreases.

b. decreases if the frequency or crystal diameterdecreases.

c. increases if the frequency increases and crystaldiameter decreases.

d. decreases if the frequency increases and crystaldiameter decreases.

The indication on the instrument display that represents the far boundary of the material being tested is called:

a. grass or hash.
b. the initial pause.
c. the main bang.
d. the back-surface reflection.

Moving a transducer over a test surface either manually or automatically is referred to as:

a. scanning.
b. attenuating.
c. angulating.
d. resonating.

A term  اصطلاحی که used in ultrasonics to express the rate at which sound waves pass through various substances is:

a. frequency.
b. velocity.
c. wavelength.
d. pulse length.

When the motion of the particles حرکت ذرات یک محیط  of a medium is transverse to the direction of propagation, the wave being transmitted is called a:

a. longitudinal wave.

b. shear wave.

c. surface wave.

d. lamb wave.

The boundary between  مرز بین two different materials دو ماده متفاوت  that are in contact with each other is called:

a. a rarefactor.
b. a refractor.
c. an interface.
d. a marker.

For discontinuity geometries other than flat, the echo amplitude دامنه اکو is usually from that observed _________ for a flat discontinuity, of similar orientation perpendicular to the sound beam.

a. identical

b. increased

c. decreased

d. elongated

To evaluate discontinuities that are oriented at anangle to the entry surface so that the sound beam strikes the plane of the discontinuity at right angles,the operator must:

a. change the frequency.

b. grind the surface.

c. angulate the transducer.

d. increase the gain.

In immersion testing, to remove the second water reflection from between the entry surface signal and the first back reflection, you should:

a.increase the repetition rate.

b.decrease the frequency.

c.decrease the sweep length.

d. increase the water path.

If a discontinuity is oriented at an angle other than90° to the sound beam, the results may be a:

a. loss of signal linearity.

b. loss or lack of signal reflected from thediscontinuity.

c. focusing of the sound beam.

d. loss of interference phenomena.

The change in direction of an ultrasonic beam whenit passes from one material to another material inwhich elasticity and density difer is called:

a.reflection 

b.rarefaction

c.angulation.

d.refraction.

In inspecting a 102 mm (4 in.) diameter threadedsteel cylinder for radial cracks extending from theroot of the threads, it would be preferable to transmit:

a.shear waves at an angle to the threads.

b.longitudinal waves from the end of the cylinder and perpendicular to the direction of the threadroots.

c. surface waves perpendicular to the thread roots.

d. shear waves around the circumference of the cylinder.

The distance from a given point on an ultrasonic wave to the next corresponding point is referred to as:

a. frequency.

b. wavelength.

c. velocity.

d. pulse length.

A testing technique in which the crystal or transducer is parallel to the test surface and ultrasonic waves enter the material being tested in a direction perpendicular to the test surface is:

a. straight beam testing.

b. angle beam testing.

c. surface wave testing.

d. lamb wave.

Which one of the following frequencies wouldprobably result in the greatest ultrasonic attenuationlosses?

a.1 MHz

b.2.25 MHz

c.10 MHz

d.25 MHz