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Safety and Precautions during welding

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  As in any welding process,   safety precautions  are very important. All information relating to the safe operation of the welding equipment and process must be fully understood before beginning work. A careless welder who does not observe some simple rules can cause a dangerous situation for everyone. The process of  arc welding creates several hazards  which must be guarded against. If the welding machine has the characteristics of a transformer or a motor-generator design, electrical energy is required as primary power to operate it. Useful safety information can be found in the Owner’s Manual that comes with each item of welding equipment. 1.  Electrical Shock: Welders must be concerned about the possibility of electrical shock. It should be remembered that electricity will always take the path of least resistance. A welder should never weld while standing in water. If wet working conditions exist, certain measures should be taken. Such measures include standing on a dry board or

Pipe Line Isometric Drawings and P & ID Drawings

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  Pipe Isometrics   : Are drawings which shows details of Process pipe lines in a single line presentation , with details of pipes, pipe connections ( valves, flanges, nipples, reducers, end cap, elbow, etc), along with the dimensions and direction of  pipe line. Example of a Pipe Line Isometric Drawings is given below in figure-A Figure A: Example of Pipe Isometric Drawing P & ID :  is called as  Piping and Instrumentation Drawing , is a pictorial representation of  Pipeline in a single line diagram along with processing Equipments/ Instruments and storage tanks . Example of a P & ID is given below in figure-B Figure B : Example of P & ID  ( Piping and Instrumentation Drawing ) This Blog gives a detail study of P&ID and Pipe Isometrics, with details of What is P&ID Drawing What is an isometric drawing Symbols of Pipe Line Isometric Drawings What is pipe rolling / off-set We shall learn from the basics, Directions: Direction symbol is given on top of Pipe Line Isome

Weld Crack

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  Weld crack   1.1. Cracking: If a weld crack is found, it must be removed and magnetic-particle inspection performed to ensure every point has been removed before re-welding. Weld Crack can occur on top of a weld bead, within the weld, or in the base metal. GMAW electrode wires are low hydrogen in content and have no flux coating to attract moisture, can help avoid cracking in the weld and heat-affected zones, if kept clean and dry. Spools or reels must be free of moisture both while being used and when being stored. A crack can easily occur on welding of aluminum, due to metal contraction as the weld pool cools, while the base metal remains hot. Cracks may be more numerous with aluminum, but they may also occur in stainless steel and galvanized materials. Cracks may occur if excess heat input is used for the particular thickness of material being welded, or steels with high carbon content, over 30 %, are likely to crack due to their hardness. Spatter: If there is a lot of spatter res

Dissimilar metal in TIG Welding process

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  Why use this TIG welding process: TIG Tungsten Inert Gas otherwise called as GTAW- Gas Tungsten Arc Welding , Involves melting the metal using the arc created by tungsten electrode, The welding can be done with or without filler metal, Argon Gas is used as shielding around the weld area, to shield the weld from atmospheric gases. As an inert gas is used for shielding the weld, the quality of weld is good without any Slag inclusions and good weld profile. TIG welding is selected to receive a high quality welds for analysis purposes   Where we use dissimilar metals ? Dissimilar metals are used in process pipe line industry, heat exchangers, boilers and Structural steel fabrication industry. SS 304/ SS316 (Austenitic Stainless Steel ) ASTM A -210  (Medium Carbon Steel) ASTM  A-36  (Low Carbon Steel )   Types of Weld Joint : Butt Joint, T Joint, Lap Joint , Corner Joint, Edge Joint Types of Joint Configuration: Joint Design:   Why we use Butt Joints To carry out the study of difference i

WELDING FOR JOISTS AND FINISHING OF MACHINING RAILS

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Unless otherwise authorized by the engineer, any welding to the top flange of  steel members for supporting floor form joists and finishing machine rails  will not be permitted. Welding of hangers and supports to shear studs will be permitted as follows: The welder must be certified and use low hydrogen electrodes and proper No welding shall be permitted when the ambient temperature of the air is below 32° F (0°C) or when the lowest temperature during the preceding 12 hours has been below 0° F (-18°C). Windbreaks or shields shall be provided when the wind chill factor is strong or cold enough to prevent welding from being carried out in a normal manner without such Welding shall not be permitted on surfaces that are wet or exposed to Arc strikes on bridge flanges must be prevented at all times. 1. Welding of Railroad Bridge Deck Floors: Railroad bridges that  span highways  are designed with a  steel deck  that covers the bridge and are welded together in the field. The special provisi

NDT Methods Selection

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  NDT Method Selection: The NDT (nondestructive testing) methods are:   Visual Inspection – VT Liquid Penetrant Testing – LT Magnetic Particle Testing – MT Radiographic Testing – RT Ultrasonic Testing – UT Eddy Current Testing – ET (not used in field inspection) Acoustic Emission Testing – AET (not used in field inspection) Phased Array Ultrasonics – PA Time Of Flight Diffraction  –  TOFD Since each NDT methods has its own set of advantages and disadvantages and some are better suited than others for a particular application, the NDT technician or engineer  must select the method  that will detect the defect or make the measurement with the  highest sensitivity and reliability . The cost effectiveness of the technique must also be taken into consideration. The following table provides some  guidance  in the selection of NDT methods for common flaw detection and measurement applications. AQC (Advanced Quality Centre) is an ISO 9001:2015 certified testing centre. We provide world class t

Weld Test Coupon Preparation

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  Bend Test Coupon Preparation First the centerline on the plate shall be marked. Then another line  1.0 inch  above the center line  and another line 1 inch below the center line. This is the section that can be used as an  alternate coupon  in the event of  corner cracks  with no evidence of slag inclusions. Next, marking of the actual  root  and face bend specimens. Using the top and bottom line, another line a minimum of  1½ inches above.   The top line shall be marked and then  1½ inches below  the bottom line. The  minimum width  of a test specimen needs to be  1½ inches  wide. After that the  Welding Inspector shall mark the weld test coupons  for a root and face bend in agreement with the welder, cutting them on a band saw. Backing Bar Removal: The  backing bar  removal can be done using a vice and using a grinder on the center of the backing bar to gouge it, about  1/16”  or so, to take the backing bar away from the back of the test plate. The welder shall  repeat this action