Welding types

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Discontinuities in Ultrasonic Testing in NDT

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 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 disco
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Acceptance Criteria for Ultrasonic Testing

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  How to interpret Acceptance Criteria for Ultrasonic Testing as per AWS D1.1 The Requirements of Ultrasonic Flaw detector equipment as per AWS D1.1 Structural Steel Welding code is given below: Equipment: The ultrasonic equipment’s shall be pulse echo type ‘A’ scan suitable for use with transducers oscillating at frequencies between  1&6 MHz. The equipment shall have valid calibration certificate .The test  equipment shall have a calibrated gain control adjustable in discrete 1 or 2 Db steps over a range of at least 60Db. Probe: Transducers/ search units with following characteristics shall be used.              Angle beam :  70° ,60°,45° (within plus minus 2°).              Crystal Size:   Crystal size shall be square or rectangular in shape and may vary from 5/8 inch to 1 inch (15mm to 25mm) in width and from 5/8 inch to 13/16 inch (15mm to 20mm) in height. The maximum width to height ratio shall be 1.2 to 1.0 and the minimum width to height ratio shall be 1.0 to 1.0. Frequency
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Welding Procedure Specification- WPS for Overlay or cladding

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  Welding Procedure Specification- WPS This document details, how to qualify a welding procedure specification-wps for weld metal overlay / cladding / surfacing , for both corrosion resistance overlay and wear resistance overlay welding. The reference standard selected for the purpose of qualification of cladding procedure and welder qualification is ASME Boiler and Pressure Vessel Code (BPVC) section IX. Step by step procedure for WPS preparation: Select the sample size (thickness of base metal) Prepare the test sample Weld the overlay / cladding over the test sample with appropriate filler metal Carry out the testings on the weld overlay as mentioned in the standard, Non Destructive Testing ( NDT ) & Mechanical Testing Prepare the Procedure qualification record ( PQR ) Prepare the Welding Procedure Specification ( WPS ) with ranges qualified for production Welder Qualification For the welder performed the PQR qualification test prepare the Welder certificate For additional welder
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