Summary of ASME BPVC Section IX – Part 3

In part – 1 of this article, we had discussed the general requirements as mentioned in part QG of ASME Section IX, To read that article please click here.

In part – 2 of this article we had discussed about the weld orientations, test positions for groove, fillet and stud welding etc. as mentioned in Part QW of ASME Setion IX. To read that article please click here.

In the present part i.e part – 3, the remaining topics i.e different tests required for procedure and performance qualifications and their acceptance criteria as mentioned in Part QW of ASME Section IX shall be discussed.

QW 141: Mechanical Tests: Mechanical tests required for Procedure qualifications or performance qualifications are;

  • Tension Tests (QW 150)
  • Guided Bend Tests (QW 160)
  • Fillet-Weld Tests (QW 180)
  • Toughness Tests (QW 171 and QW 172)
  • Stud-Weld Test

QW 150: Tension test (Tensile test): Purpose of this test is to determine the ultimate strength of groove-weld joints. Rules for specimen preparation is given in QW 151 (QW 151.1 to QW 151.4) and the specimen should conform to one of the types illustrated in figures QW 462.1 (a) to QW 462.1 (e).

Tension test procedure is given in QW 152. The tensile strength shall be calculated by using the following formula;

(Ultimate total load/least crosssectional area)

Where, Ultimate total load is the load at which specimen gets ruptured and the least cross sectional area of the specimen shall be as calculated from actual measurements made before the load is applied.

QW 153: Acceptance criteria for Tension test: This para gives the acceptance criteria for tensile test, which are the following;

  • If the specimen reaches the minimum tensile strength before rupture, then it shall be considered as accepted.
  • If the specimen breaks in the base metal outside of the weld or weld interface, the test shall be accepted as meeting the requirements, provided the strength is not more than 5% below the minimum specified tensile strength of the base metal.

For minimum value of tensile strength of base materials, required of procedure qualification, please refer Table QB/QW 422.

QW 160: Guided-Bend Test: Guided bend test is carried out to determine the degree of soundness and ductility of groove-weld joints. Rules for specimen preparation is given in QW 161 (QW 161.1 to QW 161.7).

The specimen for guided bend test is approximately rectangular in shape and is prepared by cutting the test plate or pipe. Three terms are frequently used during bend test, these are side, face and root. The cut surfaces are termed as sides. Other two surfaces are face and root surface, surface with greater width of weld is called as face surface and the surface opposite to face is known as root surface.

The specimen dimensions shall conform to the figure as illustrated QW-466.1, QW-466.2, and QW-466.3.

Guided-Bend test are of following types:

  • Side bend test – Transverse
  • Face bend test – Longitudinal and Transverse
  • Root bend test – Longitudinal and Transverse

QW 163: Acceptance criteria for Guided-bend test:

  1. The weld and heat‐affected zone of a transverse weld bend specimen shall be completely within the bent portion of the specimen after testing.
  2. There shall be no any open discontinuity in the weld or heat‐affected zone exceeding 3 mm (1/8 inch), measured in any direction on the convex surface of the specimen after bending.

QW 170: Toughness test: Purpose of this test is to determine the toughness of weldment. This test shall be carried out whenever required by any referencing codes. Test procedures and apparatus shall conform to the requirements of that referencing code. In absence of any referencing code, the test procedures and apparatus shall conform to the requirements of SA-370.

QW 171.2: Acceptance criteria for Toughness test: Acceptance criteria shall be in accordance with job requirements or the applicable specification.

QW 180: Fillet Weld Test: Purpose of Fillet weld test is to determine the size, contour, and degree of soundness of fillet welds. Rules for preparation of specimen for procedure qualification is given in QW 181.1 and corresponding figures for test specimen is given in QW 462.4 (a) and QW 462.4 (d). Rules governing the preparation of specimen for performance qualification of welders can be found in QW 181.2 and the corresponding figures are given in QW 462.4 (b) and QW 462.4 (c).

Specimen for procedure qualification shall be subjected to macro examination as per the requirements of QW 183. Whereas, for welder performance qualification one of the specimen shall be subjected to fracture test and the other specimen shall be macro examined.

Requirements for fracture test of specimens is given in QW 182 and requirements for macro examination of specimens for procedure qualification can be found in QW 183, whereas the requirements for macro examination of performance qualification specimen can be found in QW 184.

QW 190: Other tests and examinations:

QW 191: Volumetric NDE: ASME has mentioned two tests under this heading, these are the following;

  • Radiographic Examination (QW 191.1)
  • Ultrasonic Examination (QW 191.2)

QW 191.1: Radiographic Examination: Purpose of this examination is to check the soundness of welding of performance qualification test coupon. The method for Radiographic examination shall meet to the requirements of ASME Section V, Article 2. However, a written procedure for radiographic examination is not required for this purpose. The prescribed image and the image quality indicator (IQI) must be visible.

QW 191.1.1: Acceptance Criteria for Radiographic Examination: Two terminologies have been used, based on the dimensions of discontinuities, to define the acceptance criteria for Radiographic examination, these are the following;

Linear Indications: If the length of discontinuity is more than three times the width of the discontinuity, then it is called as Linear discontinuity i.e

L > 3 W;

Where, L – Length of discontinuity

           W – Width of discontinuity

Cracks, Lack of penetration, Lack of fusion are common examples of Linear indications.

Rounded Indications: If the length of discontinuity is less than or equal to three times the width of the discontinuity, then it is defined as Rounded discontinuity i.e

L ≤ 3 W;

Where, L – Length of discontinuity

           W – Width of discontinuity

Porosity and inclusions are common examples of Rounded indications.

Acceptance criteria for Linear Indications:

  • Any type of crack, incomplete fusion and incomplete penetration shall be considered unacceptable.
  • Any elongated slag inclusion, shall be considered unacceptable, which has a length greater than
  1. 3 mm (1/8 in.) for T less than to 10 mm (3/8 in.)
  2. T/3 for T greater than or equal to 10 mm (3/8 in.) and less than or equal to 57 mm (2-1/4 in.) i.e. 10 mm ≤ T ≤ 57 mm.
  3. 19 mm (3/4 in.) for T greater than 57 mm (2-1/4 in.)

         (Where, ‘T’ – Thickness of deposited weld metal)

  • Any group of slag inclusions (in line) with an aggregate length more than T (within a length of 12T) shall be considered unacceptable except when the distance between the successive discontinuities exceeds 6L.

         (where ‘L’ is the length of the longest imperfection in the group).

Acceptance criteria for Rounded Indications:

  • The maximum acceptable dimension for rounded indications shall be 20% of T or 3 mm (1/8 in.), whichever is smaller.
  • For a material thickness less than 3 mm (1/8 in.), the number of maximum acceptable rounded indications are 12 for 150 mm (6 in.) weld length. The number of acceptable rounded indication shall be decreased proportionately for weld length less than 150 mm (6 in.).
  • For a material thickness equal to or more than 3 mm, refer figure QW 191.1.2.2 (b) (4) for acceptance criteria. Rounded indications less than 0.8 mm (1/32 in.) in maximum diameter shall not be considered in the radiographic acceptance tests of welder performance qualification in these ranges of material thicknesses.

QW 191.2: Ultrasonic Examination: Ultrasonic examination may be conducted for performance qualification test coupons for material thickness more than or equal to 6 mm (1/4 in.).

A written procedure shall be required for performing the ultrasonic examination. The test method, procedure and qualifications shall meet the requirements of ASME section V, Article IV.

QW 191.2.3: Acceptance Criteria for Ultrasonic Examination:

  • All indications interpreted as cracks, lack of fusion or lack of penetration are shall be considered unacceptable regardless of length.
  • Any indication, shall be considered unacceptable, which has a length greater than
  1. 3 mm (1/8 in.) for T up to 10 mm (3/8 in.)
  2. T/3 for T greater than or equal to 10 mm (3/8 in.) and less than or equal to 57 mm (2-1/4 in.) i.e. 10 mm ≤ T ≤ 57 mm.
  3. 19 mm (3/4 in.) for T greater than 57 mm (2-1/4 in.)

         (Where, ‘T’ – Thickness of the weld metal excluding any allowable reinforcement)

Other tests which are mentioned in ASME Section IX are the following;

  • Stud Weld Test (QW 192)
  • Tube to Tubesheet Tests (QW 193)
  • Visual Examination – Welder Performance Qualification (QW 194)
  • Liquid Penetrant Examination (QW 195)
  • Resistance Weld Testing (QW 196)
  • Laser Beam Welding (LBW) Lap Joint Tests (QW 197)
  • Flash Welding (QW 199)

We have discussed the most demanding topics of Part QG and Article 1 Part QW of ASME Section IX. Other articles viz. Article 2, Article 3, Article 4 and Article 5 shall be covered later. please leave your valuable suggestions and feedback about the quality and contents of my articles.

(Note: Purpose of this article is to give a general guideline to the readers and it shall not be considered as a substitute of code. For full terms and conditions please read ASME Section IX, 2017 edition.)

Thank you!

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