Plasma arc welding (PAW) is an arc welding process in which the heat required for welding is generated by a constricted arc between a non-consumable electrode and the workpiece. Plasma Arc Welding is essentially an extension of Gas Tungsten Arc Welding (GTAW). Like GTAW, a non-consumable electrode is used in Plasma Arc Welding (PAW). However, …
In this article, the weld defect acceptance/rejection criteria are given for the following tests/NDT; 1. Acceptance criteria for Visual Inspection 2. Acceptance criteria for Radiography Test (RT) 3. Acceptance criteria for Ultrasonic Test (UT) 4. Acceptance criteria for Liquid Penetrant Test (LPT/LPI/DPT) 5. Acceptance criteria for Magnetic Particle Test (MPI/MPT/MT) (This article covers the weld …
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 the weld orientations, test positions for the groove, fillet and stud welding, etc. as mentioned in …
In part – 1 of this article, we had discussed the general requirements as mentioned in part QG of ASME BPVC Section IX. To read part – 1 of this article please click here. This article will cover the Part QW of ASME section IX, which is dedicated to the general requirements in the welding. Part …
ASME Boiler and Pressure Vessel Code (BPVC), Section IX contains qualification standard for the following; Welding, Brazing, and Fusing procedures Welders and welding operators Brazers and brazing operators Plastic fusing operators Section IX is a reference document for the qualification of material joining (welding, brazing, and plastic fusing) processes, used by various construction codes such …
Magnetic Particle Testing (MT) (also known as magnetic particle inspection – MPI) is a non destructive test (NDT) method, used to detect surface or subsurface (near to surface) discontinuities. This NDT method can be used on metals which can be easily magnetized (ferromagnetic). Metals can be classified as ferromagnetic, paramagnetic, or diamagnetic. Ferromagnetic metals: Ferromagnetic …
Oxy-fuel welding (OFW) is also known as Gas welding or Oxy-fuel gas welding. The term ‘Oxy-fuel’ is used to denote a combination of Oxygen and a Fuel gas, means it’s a process in which Oxygen and a fuel (combustible gas) both are required. Most commonly used fuel gas is Acetylene and thus the name Oxy-Acetylene …
(OFW) Oxy-Fuel Welding (Gas Welding/Oxy-Acetylene Welding) Read More »
Thickness range for performance qualification (welder qualification test): ASME BPVC Section IX has provided guidelines for the thickness range up to which a welder can weld. This can be found in Table – QW 452.1(b) of ASME BPVC Section IX. A simplified version of that table is given below; According to this table, three important …
Thickness range for welder qualification and procedure qualification (ASME Section IX) Read More »
ASME Boiler and pressure vessel code (BPVC) has assigned certain numbers to base metals (to be welded) as well as to filler metals (electrodes). For base metals, ASME has assigned two number system, these are; P Numbers Group Numbers For filler metals, the number system which is assigned, are as follows; F Number A Number …
P Number, F Number and A Number in welding (ASME Section IX) Read More »
Heating the base metal to a specific desired temperature before welding is called as preheating. The temperature at which the base metal is heated is called as the preheat temperature. Preheat temperature can be determined by the applicable code. Please see table 1 to know how to find the preheat temperature in the respective code: …
Submerged Arc Welding (SAW) is an arc welding process in which arc is generated between a bare electrode and the workpiece. The arc and the molten weld pool are submerged in a blanket of granular fusible flux on the workpiece. Flux covers the arc and prevents fumes, sparks, spatter, and intense ultra violet radiation from …
Flux cored arc welding (FCAW) is a welding process that uses the heat produced by an arc generated between a continuous tubular filler metal (electrode) and the work piece. The filler metal is hollow with flux at the core. Flux present at the core of the filler metal shields the molten weld pool from atmospheric …
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 …
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 …
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 …
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 an alloy of tungsten). In TIG welding, the arc is generated between the tungsten electrode and the workpiece to produce the necessary heat required …
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 …
How to write a Welding Procedure Specification (WPS) Read More »
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 …
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 …
Any discontinuity (or irregularity) 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 called as a defect only when if it exceeds the specified code limit, hence we can say that every defect present in the weld metal …
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 …
Radiography testing (RT) is one of the most widely used non-destructive test (NDT) methods. With the help of this method, we can detect hidden flaws or discontinuities present in welds such as cracks, porosity & blowholes, slag, flux or oxide inclusions, lack of fusion, incomplete penetration, Mismatch, and tungsten inclusion, etc. Short wavelength electromagnetic radiations …
1. Which of the following butt weld preparations is generally most susceptible to lack of side wall fusion during MMA welding? A “U” preparation A “V” preparation A Double V preparation All of the above 2. Which of the following units is used for charpy V notch energy? Pounds per square inch Joules KSi All …
1. Which of the following processes joins metals plastically? Friction welding Resistance welding Plasma welding None of the above 2. In submerged arc welding, excessive arc voltage may cause? Excessive penetration Change in weld metal composition Narrow weld width All of the above 3. In a tensile test, a brittle material would be indicated …
1. Which of the following NDT methods can only detect surface breaking defects? MPI DPI UT RT 2. Which of the following is applicable to electrode efficiency? The mass of metal deposited as a percentage of the mass core wire melted Iron powder electrodes have efficiencies above 100% Electrodes of high efficiencies tend …
1. Which of the following does not require baking; E 6010 E 7018 Both a & b None of the above 2. Gamma rays and X-rays are part of a family of waves called Acoustic waves Light waves Electromagnetic waves Transverse waves 3. Why is hot – pass so-called? Because it …
1. Overlap in welds could be influenced by: Welding process Welding position Poor welding technique All the above 2. In MAG/CO2 welding which parameter gives the greatest control of weld appearance during dip transfer or short-circuiting welding? Wire stick-out length Welder’s convenience Wire feed speed Inductance 3. In X-ray work the quality of the radiographic …
