High frequency sound waves (frequency > 20000 HZ) also known as ultrasonic waves are introduced in a test object through a probe, these waves travel through the material on a predictable path. The waves are reflected at interfaces or other interruptions or discontinuity. The reflected waves are detected and then analysed for the possibility of any discontinuity in the test object. Sound beam is emitted through a probe. The probe….
SELECTION OF PROBE ANGLE: There are three methods for selecting a probe angle, these are: Based on groove angle: Probe Angle (Ø) = 90 – α/2 Where, α – Groove angle and Ø- Probe Angle As per AWS: 0 – 30 mm Thickness – 700 Probe 30 – 40 mm Thickness – 600 Probe > 40 mm Thickness – 450 Probe As per approved procedure:….
Visual examination of weld joint is an important activity, carried out to check the integrity and soundness of the weldment. It is an economical activity, as it doesn’t require any costly equipment. It must be carried out by a well experienced inspector. Main responsibilities of a welding inspector are: Code compliance Workmanship control Documentation Control The requirements of visual examination are: Illumination should be at least 350 Lux (minimum) but….
Gas Tungsten Arc Welding (GTAW) is also known as Tungsten Inert Gas Welding (TIG Welding). It is an arc welding process that uses a non-consumable electrode made up of Tungsten (or alloy of tungsten). Arc is generated between the tungsten electrode and work piece to establish the weld pool. Inert gas (Argon or Helium) is used to shield the molten weld pool during welding. Additional filler metal may be added….
A welding procedure specification (WPS) is a written document providing direction to the welder (or welding operator). It contains all the necessary parameters viz. joints, base metals, filler metals, positions, preheat, PWHT, gas etc. (including ranges, if any) under which the welding process must be performed. These parameters are known as variables (as per ASME Section IX). Three types of variables are mentioned in the code, these are; Essential Variable….
Hydrotest a kind of pressure test in which the component being tested is filled completely with water or another liquid. Pressure, if required, is then applied to the liquid for the required time and the outside of the component is examined visually for leaks. Let us see, how the test from planning through execution is done. Preparation of System Test Package List of Instruments and status Pre-test Inspection Pressurizing /….
Sections of ASME Boiler and Pressure vessel Codes (BPVC) The following list includes some of the most widely used Boiler and Pressure Vessel codes (BPVC) prepared and published by ASME. Section I……………………Rules for construction of Power Boilers Section II…………………..Materials Part A. Ferrous Material Specifications Part B. Nonferrous Material Specifications Part C. Specifications for Welding, Rods, Electrodes and Filler Metals Part D. Properties Section III………………….Rules for Construction of Nuclear Facility Components Subsection….
Any irregularity (discontinuity or flaw) in the weld metal, which exceeds the applicable code limit, is termed as a WELD DEFECT (or Welding Defect). Please note that a discontinuity can be termed as a defect only when, if it exceeds the specified code limit, hence we can say that every defect present in a weld metal is a discontinuity but every discontinuity present in the weld metal may not necessarily be a….
About radiography films: Radiography films are primarily made up of two things; 1. Base 2. Emulsion Base: Base is a transparent, flexible blue tinted object, usually made from a clear and flexible plastic such as cellulose acetate. It provides physical support to emulsion and does not participate in the image-forming process. It is not sensitive to radiation, nor can it record an image. Emulsion: Emulsion consists of gelatin which consists of….
Radiography testing (RT) is one of the most widely used non destructive test (NDT) method. With the help of this method we can detect hidden flaws or discontinuities present in welds such as cracks, porosity & blow holes, slag, flux or oxide inclusions, lack of fusion, incomplete penetration, Mismatch and tungsten inclusion etc. Short wavelength electromagnetic radiations such as X-rays or Gamma rays (γ) are used for Radiography testing. Both….