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Welder’s Handbook
For Gas Shielded Arc Welding, Oxy Fuel Cutting & Plasma Cutting

Published by: Air Products PLC

Designed and produced by: PDF Conceptual Design & Marketing

Copyright: Air Products PLC 1999 – 3rd Edition

Air Products Welder’s Handbook


Introduction Fusion welding Why use welding? Arc welding processes Welding terms MIG/MAG welding TIG welding Plasmawelding Welding sheet Welding plate Welding pipes Defects in welds The right gas: MIG/MAG welding TIG welding Welding data: MIG/MAG welding Flux cored electrodes TIG welding Oxy-fuel gas cutting Plasma cutting Safety always Conversion data 30 33 34 37 44 46 inside back cover 26 29 2 3 4 5 6 10 17 18 20 22 24


Air Products Welder’s Handbook

Fusion welding
The most widely used weldingprocesses rely on fusion of the components at the joint line. In fusion welding, a heat source melts the metal to form a bridge between the components. Two widely used heat sources are:
high current low voltage supply

'T' joint

fillet weld

Butt joint


butt weld

Electric arc

fuel gas flame


air must be excluded from heated area

Gas flame The moltenmetal must be protected from the atmosphere - absorption of oxygen and nitrogen leads to a poor quality weld. Air in the weld area can be replaced by a gas which does not contaminate the metal, or the weld can be covered with a flux.



Why use welding?
Welding is used because it is: q one of the most cost-effective methods of joining metal components q suitable forthicknesses ranging from fractions of a millimetre to a third of a metre q versatile, being applicable to a wide range of component shapes and sizes The joints produced by welding are: q permanent q strong, usually matching the strength of the components, q leak tight, q reproducible, q readily inspected by nondestructive techniques. Welding can be used: q in the workshop q on site for q sheet q plate qpipe q sections

Which process?
A large number of welding processes and techniques are available. No process is universally best. Each has its own special attributes and must be matched to the application. Choosing the most suitable process requires consideration of a number of factors.

Factors in choosing welding process:
q type of metal q type of joint q production constraints q equipmentavailability q labour availability q health, safety and the environment q costs of consumables q labour costs q material thickness


Air Products Welder’s Handbook


Arc welding processes
Fabrications involving sheet metal, plate or pipes are commonly welded by an arc process.

Two of the most important processes use a gas shield to protect the weld metal from atmosphericcontamination.



Terms commonly used in gas shielded welding
arc length Distance between the tip of the electrode and the surface of the weld pool. base metal Incorrectly used to describe the metal from which the components of the joint are made. The correct term is parent metal. bead A single run of weld metal deposited onto the surface of the parent metal. burn-off rateThe rate at which the wire is melted. Quoted as a linear measurement - m/min (metres per minute) or in/min. deposited metal Material which is added, either from the electrode or filler wire, to build up the weld profile. deposition rate The rate at which melted electrode metal is added to the weld pool. Quoted in kg/hr (kilograms per hour). Sometimes incorrectly used in reference to the ratio ofmetal deposited to the amount of electrode melted - this is the deposition efficiency. electrode The flux coated rod in manual metal arc welding, the tungsten in TIG and plasma welding and the consumable wire in MIG/MAG welding. The arc is formed between the parent metal and one end of the electrode.

filler metal Metal added to the weld pool during welding. For TIG it is supplied as cut lengths...