Inspection and Testing

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4.1 General terms regarding weld quality

Weld Quality

The following are typical requirements for the quality of weld products.

  • The product is finished accurately in accordance with the design dimensions.
  • The product offers the required functionality and strength (or safety).
  • The appearance of the weld satisfies the required level.

The basic conditions of welding quality to achieve products of such high quality includes the following:

  • No cracks or holes found in the bead.
  • The bead has uniform waves, width and height.
  • The finished product satisfies the design dimensions and has almost no distortion.
  • The welding meets the required strength.
  • Full penetration welds that fuse and join the entire interface between the base materials or a weld joints including partial penetration welds should be used appropriately to ensure the necessary rigidity.

Weld defects

Stages of inspection

Types of inspection

Types of testing

Difference between inspection and testing

Failure analysis

4.2 Destructive testing (procedure as per ASTM / ASME sec. v and Acceptance criteria as per ASME sec. viii div.1)

Tensile testing

Compressive testing

Impact testing

Hardness testing

Weld bend testing

Fracture toughness testing

4.3 Non-destructive testing (procedure as per ASTM / ASME sec. v and Acceptance criteria as per ASME sec. viii div.1)

Liquid Penetrant Testing (LPT)

Magnetic Particle Testing (MPT)

Ultrasonic Testing (UT)

Radiographic Testing (RT)

Eddy Current Testing (ECT)

4.4 Special type of testing for equipment / piping operation

a) Hydrostatic test of pressure vessel: This test is performed to check the structural integrity of the pressure vessel. The vessel is filled with water and pressurized to a level higher than the design pressure. The pressure is then held for a specified duration to ensure that there are no leaks or deformations. The test is conducted in accordance with the relevant design codes and standards.

b) Hydrostatic test of piping spools: This test is performed to check the structural integrity of the piping spools. The spools are filled with water and pressurized to a level higher than the design pressure. The pressure is then held for a specified duration to ensure that there are no leaks or deformations. The test is conducted in accordance with the relevant design codes and standards.

c) Pneumatic test: This test is performed to check the structural integrity of the piping system. The system is pressurized with air or nitrogen to a level higher than the design pressure. The pressure is then held for a specified duration to ensure that there are no leaks or deformations. The test is conducted in accordance with the relevant design codes and standards.

d) Helium leak test: This test is performed to detect and locate leaks in the piping system. Helium gas is used as a tracer gas, which is injected into the system. The system is then pressurized with air or nitrogen to a level higher than the design pressure. The presence of helium gas outside the system indicates the location of the leak. The test is conducted in accordance with the relevant design codes and standards.

4.5 Running inspection methods.

a) Visual Inspection by Eye Contact:

This is the most common and widely used method of inspection. It involves visually examining the surface or structure for visible defects, irregularities, or anomalies. Inspectors rely on their eyes to identify issues such as cracks, discontinuities, weld defects, surface finish problems, and more.

b) Visual Inspection by Smell:

While less common, the sense of smell can be utilized in certain situations. For example, in industries where certain materials emit distinctive odors during normal operation, an unusual or abnormal smell might indicate a problem. This method is not as precise as other analytical techniques, but it can serve as an additional tool for identifying issues.

c) Visual Inspection by Hand Touch:

Tactile inspection involves physically touching the surface or structure to detect variations, irregularities, or defects that may not be immediately visible. This is particularly useful for assessing surface roughness, weld bead profile, or identifying inconsistencies that can be felt through touch.

d) Visual Inspection by Hearing:

While less common than the other senses, hearing can sometimes be used for inspection. For example, certain defects in rotating machinery or structures may produce distinct sounds. Unusual noises, vibrations, or changes in the acoustic signature during operation can indicate potential issues.

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