Ultrasonic Testing(UT) Inspection Services

What is the defect size accepted in Ultrasonic Testing ?

Indications which are identified using any NDT method is accepted or rejected in reference with the standards. The standards which client accepts or the standard which we follow for production  is called as acceptance criteria. Few of the important acceptance criteria are given in this blog.For more detailed understanding of NDT, Ultrasonic testing(UT) inspection services and defects visit us on https://aqcinspection.com/

Ultrasonic TestingAcceptance Criteria :

ASME Section VIII Division 1 – Pressure Vessel Construction – Ultrasonic Testing (UT) Inspection Services

 These Standards shall apply unless other standards are specified for specific applications within this Division.
Imperfections which produce a response greater than 20% of the reference level shall be investigated to the extent that the operator can determine the shape, identity, and location of all such imperfections and evaluate them in terms of the acceptance standards given in (a) and (b) below.
  • Indications characterized as cracks, lack of fusion, or incomplete penetration is unacceptable regardless of other imperfections are unacceptable. If the indications exceed the reference level amplitude and have lengths which exceed:
    • 1/4 in. (6 mm) for t up to 3/4 in. (19 mm);
    • 1/3t for t from 3/4 in. to 21/4 in. (19 mm to 57 mm); (3) 3/4 in. (19 mm) for t over 21/4 in. (57mm).
where t is the thickness of the weld excluding any allowable reinforcement. For a butt weld joining two members having different thicknesses at the weld, t is the thinner of these two thicknesses. If a full penetration weld includes a fillet weld, the thickness of the throat of the fillet shall be included in it .

 ASME B 16.34 – Valves – Ultrasonic Testing

Acceptance Standards.

Straight Beam Examination

Indications which are equal to or exceed that obtained from a 6.4 mm (0.25 in.) diameter flat bottomed hole in a calibration test piece of thickness equal to the defect depth are unacceptable.

Angle Beam Examination

Indications which are equal to or exceed those obtained from a 60 deg V-notch, 25 mm (1.0 in.) long and having a depth not greater than 5% of the nominal wall thickness in a test piece are unacceptable.

ASME B 31.1 – Power Piping – Ultrasonic Testing .

Welds that are shown by ultrasonic examination to have discontinuities that produce an indication greater than 20% of the reference level shall be investigated to the extent that ultrasonic examination personnel can determine their shape, identity, and location so that they may evaluate each discontinuity for acceptance in accordance with (B.1) and (B.2) below.
(B.1) Discontinuities evaluated as being cracks, lack of fusion,. or incomplete penetration are unacceptable regardless of length.
(B.2) Other discontinuities are unacceptable if the indication exceeds the reference level and their length exceeds the following:
(B.2.1) ¼” (6.0 mm) for t up to ¾” (19.0 mm).
(B.2.2) 1/3 t for t from ¾” (19.0 mm) to 2 ¼ “ (57.0 mm).
(B.2.3) ¾”. (19.0 mm) for t over 2¼” (57.0 mm)
Where t is the thickness of the weld being examined. If the weld joins two members having different thicknesses at the weld, t is the thinner of these two thicknesses.

ASME B31.3 Process Piping – Ultrasonic Testing

 Inspection of Weld Joints carried as per ASME Section V , Article 4

Pipe and Tubing

  • Pipe and tubing, required or selected in accordance with Table K305.1.2 to undergo ultrasonic examination, shall pass a 100% examination for longitudinal defects in accordance with ASTM E213 Ultrasonic Testing of Metal Pipe and Tubing. Longitudinal (axial) reference notches shall be introduced on the outer and inner surfaces of the calibration (reference) standard in accordance with Fig. 3(c) of ASTM E213 to a depth not greater than the larger of 0.1 mm (0.004 in.) or 4% of specimen thickness and a length not more than 10 times the notch depth.
  • Acceptance Criteria. Any indication greater than that produced by the calibration notch representation
Welds over 6mm thick can be ultrasonically tested in reference with procedure given in ASME
Sec V article 4.
Indications shall be sized using the applicable technique(s) provided in the written procedure for the examination method. Indications shall be evaluated for acceptance as follows:
  • All indications characterized as cracks, lack of fusion, or incomplete penetration are unacceptable regardless of
  • Indications exceeding 1/8 in. (3 mm) in length are considered relevant, and are unacceptable when their lengths exceed
  • 1/8 in. (3 mm) for t up to 3/8 in. (10 mm).
  • 1/3t for t from 3/8 in. to 21/4 in. (10 mm to 57 mm).
(3) 3/4 in. (19 mm) for t over 21/4 in. (57 mm),
where “t” is the thickness of the weld excluding any allowable reinforcement.
For a butt weld joining two members having different thicknesses at the weld, t is the thinner of these two thicknesses.
If a full penetration weld includes a fillet weld, the thickness of the throat of the fillet shall be included in t .

API 1104 Welding of Pipelines & Related Facilities – Ultrasonic Testing – Acceptance level


  • Acceptance Standards 9.6.2.1 Indications determined to be cracks (C) shall be considered

  • Linear surface (LS) indications (other than cracks) interpreted to be open to the D. or O.D. surface shall be considered defects should any of the following conditions exist:
    1. The aggregate length of LS indications in any continuous 12”(300-mm) length of weld exceeds 1”. (25 mm).
    2. The aggregate length of LS Indications exceeds 8% of the weld

  • Linear buried (LB) indications (other than cracks) interpreted to be subsurface within the weld and not I.D. or O.D. surface-connected shall be considered defects should any of the following conditions exist:
    1. The aggregate length of LB indications in any continuous 12”(300-mm) length of weld exceeds 2” (50 mm).
    2. The aggregate length of LB indications exceeds 8% of the weld

  • Transverse (T) indications (other than cracks) shall be considered volumetric and evaluated using the criteria for volumetric indications. The letter T shall be used to designate all reported transverse indications.

  • Volumetric cluster (VC) indications shall be considered defects when the maximum dimension of VC indications exceeds 1/2 “ (13 mm).
  • Volumetric individual (VI) indications shall be considered defects when the maximum dimension of VI indications exceeds 1/4 “ (6 mm) in both width and
  • Volumetric root (VR) indications interpreted to be open to the D. surface shall be considered defects should any of the following conditions exist:
    1. The maximum dimension of VR indications exceeds 1/4“ (6mm).
    2. The total length of VR indications exceeds 1/2 “ (13 mm) in any continuous 12” (300 mm)

Comments

Post a Comment

Popular posts from this blog

Discontinuities in Ultrasonic Testing in NDT

Image
 This blog will discuss types of discontinuities that can be evaluated with the ultrasonic testing in NDT method. Discontinuities can be divided into three general categories inherent, processing and service Inherent discontinuities are usually formed when the metal is molten. Inherent wrought discontinuities relate to the melting and solidification of the original ingot before it is formed into slabs, blooms and billets. Inherent cast discontinuities relates to the melting, casting and solidification of a cast article. Usually caused by inherent variables such as inadequate feeding, gating, excessive pouring temperature or entrapped gases. Processing discontinuities are usually related to the various manufacturing process such as machining, forming, extruding, rolling, welding, heat treating and plating. Service discontinuities are related to the various service conditions such as stress, corrosion, fatigue and erosion. During the manufacturing process, many d...
Read more

NDT on Shafts

Image
  Non Destructive Testing,NDT on Shafts is considered essential , because the shafts are mostly made as load bearing structures, any defects such as cracks will propagate more during acting of load and eventually will cause failure. The most possible defects in shafts are Cracks and Pipes , which is shown below The Non Destructive methods preferred for defect detection on raw material shafts are Ultrasonic Testing, Magnetic Particle testing / Eddy Current Testing / Magnetic Flux Leakage method. We have not discussed about other NDT methods such as Liquid Penetrant testing & Radiographic testing because for raw material inspection. These methods will be cost effective for raw material testing  ( i.e. most costly and labor intensive, also there is possibility of missing out the cracks in radiography testing due to orientation of crack ) The Defect wise identification method is given as below  , Internal Defect ( Piping ) – Ultrasonic Testing Surface Defects  (C rac...
Read more

Standards for Welding Positions

Image
  Standards for Welding Positions : It is very important for the Weld Inspector  to know the position , or location of a joint relative to the horizon, because it may determine what welding process, methods, and techniques can be used. Welding is usually easiest when the welder can work on a joint located on a flat, horizontal surface, such as on a table or bench. However, joints in the field may be located in a variety of positions relative to the welder and to the horizon, as shown below.  1)  Welding positions – AWS D1.1, European Welding Standard EN 287 – 1, ASME IX: 2) Welding Positions – Butt, Fillet and Piping Welds: Flat Butt Weld Position – 1G In this position, the axis line of the weld must  not incline more than 15°  from the horizon and the face of the weld must be on top. Welders often refer to the flat-position welding by the nonstandard term  downhand welding. Horizontal Butt Weld Position – 2G In this position, both plates are perpendic...
Read more