Welding

Introduction to SAW 263

This class describes submerged arc welding (SAW) and the modes, equipment, and consumables it uses. In SAW, the arc and weld puddle are buried under a blanket of loose flux material. The consumable electrode is a continuous wire fed through a welding gun or welding head, depending on the SAW mode. SAW modes include semi-automatic and automatic. Automatic SAW is the most common mode. The mode also affects the specific equipment in an SAW system, but all systems require a power source, a wire feeder, and a flux delivery system.

Although SAW can only be performed in the flat or horizontal position, it has many other advantages. The blanket of flux thermally insulates the weld, which helps prevent discontinuities, and the high current results in excellent weld penetration. These benefits make SAW a popular choice for a range of applications. After taking this course, users will have the foundational understanding necessary to safely and effectively perform SAW.

  • Difficulty Intermediate

  • Format Online

  • Number of Lessons 14

  • Language English

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Course Outline
  • Submerged Arc Welding
  • SAW Advantages and Limitations
  • Common SAW Applications
  • SAW Basics Review
  • Modes of SAW
  • SAW Equipment
  • SAW Power Sources
  • SAW Equipment and Modes Review
  • SAW Electrodes
  • Electrode Classifications
  • SAW Fluxes
  • Flux-Electrode Classifications
  • SAW Safety
  • SAW Consumables and Safety Review
Objectives
  • Describe submerged arc welding.
  • Distinguish between advantages and limitations of SAW.
  • Describe common SAW applications.
  • Distinguish between the different modes of SAW.
  • Describe SAW equipment.
  • Describe SAW power sources.
  • Describe SAW electrodes.
  • Identify SAW electrodes based on the AWS classification system.
  • Describe SAW fluxes.
  • Identify SAW flux-electrode combinations based on the AWS classification system.
  • Describe SAW safety considerations.
Glossary
vocabulary term
Definition

active flux

A type of SAW flux containing small amounts of silicon or manganese that transfer to the weld metal to alter its composition. The amount of silicon or manganese transferred from active flux to the weld depends on the voltage.

alloy flux

A flux containing alloying elements that transfer to the weld to create alloy welds. Alloy flux must be used with a plain carbon steel electrode.

alloying elements

A material that is intentionally added to a metal in order to change its properties. Alloying elements can improve the strength, ductility, hardness, and toughness of a finished weld.

alloys

A metal consisting of a mixture of two or more elements, one of which must be a metal. Alloys combine the beneficial properties of the mixed elements.

alternating current

AC. An electrical current that reverses direction at regularly recurring intervals of time. In the United States, alternating current switches direction 60 times per second, or 60 hertz (Hz).

American Welding Society

AWS. The non-profit organization that regulates industrial standards for welding. The American Welding Society also promotes the welding industry in the United States.

amperage

The amount of current flowing through a circuit. Amperage is measured in amperes (A), or amps.

arc

The area in which electricity transfers between the electrode and the workpiece. The arc generates the heat that melts the base metals and filler metal during welding.

arc radiation

The emission of ultraviolet and infrared rays from an electric arc. Arc radiation can burn eyes and skin.

arc welding

A group of welding processes that use electricity to generate the heat needed to melt the base metals. Arc welding is portable and economical, making it the most common form of welding.

atmospheric contaminants

Any element of the surrounding environment that can impact the quality and strength of a finished weld. Atmospheric contaminants are usually ambient gases such as oxygen and nitrogen.

automatic SAW

A mode of SAW in which mechanical equipment holds the electrode and guides it along the joint with minimal operator involvement. Automatic SAW systems typically use a welding head and travel carriage or a manipulator.

AWS

American Welding Society. The non-profit organization that regulates industrial standards for welding. The AWS also promotes the welding industry in the United States.

carbon

A common nonmetallic element found in all types of steel. Increasing the carbon content of a metal typically increases hardness.

chrome

A hard gray metal that is highly resistant to corrosion and wear. Chrome is often used in hardfacing to create a wear-resistant layer on base metals.

circuit

A controlled path for electricity. All arc welding processes require a closed electrical circuit that includes a source, path, load, and control.

circumferential welds

A weld produced around the outer or inner surface of a cylindrical workpiece. Circumferential welds are used to fabricate structural pipes.

complete joint penetration

CJP. A weld condition that occurs when weld metal extends throughout the full thickness of the base metals, completely filling the joint. SAW minimizes the amount of metal required to achieve complete joint penetration.

composite electrodes

An electrode made of a solid steel sheath and an iron powder core. Composite electrodes, also known as cored electrodes, are identified with a "C" in the AWS electrode classification system.

constant current

CC. A power supply in which the amperage is set at a fixed level and the wire feed speed (WFS) varies to maintain the constant amperage. With constant current power, the voltage is also set at a fixed level and maintained by the varying WFS.

constant voltage

CV. A power supply in which the voltage is set at a fixed level and the amperage varies to maintain the constant voltage. With constant voltage power, the wire feed speed (WFS) is also set at a fixed rate and maintained by the varying amperage.

consumable electrode

An electrode that conducts electricity to the arc and also melts into the weld as filler metal. SAW uses a consumable electrode in the form of a wire.

contact nozzle

The component of a welding gun or head where the electrode is energized by the contact tip. Contact nozzles are usually made of copper.

cored electrodes

An electrode made of a solid steel sheath and an iron powder core. Cored electrodes, also known as composite electrodes, are identified with a "C" in the AWS electrode classification system.

cross seam adjuster

A device used to tilt the welding head slightly to either side. The cross seam adjuster and the cross slides allow operators to fine-tune the position of the welding head.

cross slides

A device used to adjust the position of the welding head either vertically or horizontally. The cross slides are adjusted by using a hand-crank.

current

The flow of electricity through a circuit. Current is measured in amperes (A), or amps, and controls the heat of the arc.

deposition rate

The rate at which filler metal melts off the electrode and into the weld puddle, which is measured in pounds per hour (lb./hr) or grams per minute (g/m). In SAW, the deposition rate depends on the amperage, the number of electrodes, and the polarity of the current.

diffusible hydrogen

The maximum amount of hydrogen, given in milliliters (mL), that will be present per 100 grams (g) of weld metal. A flux-electrode classification may include a designation for diffusible hydrogen.

direct current

DC. An electrical current that flows in one continuous direction. Direct current does not reverse the direction of flow.

discontinuities

An irregularity in the specified and expected composition of a weld. Discontinuities are not always defects.

dust mask

A protective nose and mouth covering that filters out some airborne particles. Dust masks help protect operators from inhaling particles of the loose flux used in SAW.

electric shock

The flow of electricity through the body. Severe electric shock can be fatal.

electrode

A device in an electrical circuit that conducts electricity. A welding electrode can also serve as filler metal.

filler metal

Metal deposited into the weld that often adds strength and mass to the welded joint. In SAW, filler metal is provided by the wire electrode.

fit-up

A measure of the closeness between two parts that are to be welded. Proper fit-up occurs when parts fit together without extra spaces or gaps.

flux

A nonmetallic material used to protect the weld puddle and arc from atmospheric contamination. SAW uses a blanket of loose, granular flux that covers the arc and weld puddle.

flux delivery system

A collection of hoses and tubes that transport flux from a storage container to the weld area. Flux delivery systems may transport flux to an SAW gun, a flux hopper, or a flux dispensing nozzle.

flux hopper

A container that receives flux from a flux tank and dispenses it through a nozzle. A flux hopper is mounted on a travel carriage for SAW.

flux recovery system

A vacuum-powered assembly used to collect used flux material from SAW. Flux recovery systems are most commonly used with automatic SAW.

flux tank

A pressurized container with rubber hoses used to store and deliver flux. A flux tank can be combined with a wire feeder for SAW.

foot-pounds

ft.-lbs. A unit used to measure energy in the English system. One foot-pound is equal to the amount of energy needed to move one pound a distance of one foot.

frequency

The rate at which an alternating electrical current changes direction. Frequency is typically measured in hertz (Hz), or cycles per second.

hardfacing

A metalworking process that welds a harder or tougher material, especially chrome, to base metals. Hardfacing adds a wear-resistant layer on top of the base metals.

heat treatment

A controlled heating and cooling process used to change the structure of a material. Heat treatment alters a material's physical and mechanical properties.

hydrogen

A colorless, odorless gas that is the most abundant element on the planet. Hydrogen can cause weld metal to crack.

impact strength

The measure of a material's ability to withstand sudden, sharp blows without fracturing or breaking. The impact strength of a weld can be determined by putting the weld through different types of impact testing.

incomplete penetration

A discontinuity characterized by an unpenetrated and unfused area in a joint. Incomplete penetration occurs when weld metal does not extend through the thickness of the joint.

infrared

Invisible rays of light energy emitted by heated objects. Infrared rays can damage vision.

inverter

A device designed to convert AC power to DC power. Inverters are often used in welding power sources because they can change the frequency to operate more efficiently.

inverter power sources

A welding machine that uses an inverter to supply electricity to the welding circuit. Inverter power sources operate at variable frequencies and amplitudes and are energy efficient.

low-alloy steel

A type of steel that contains small amounts of intentionally added materials that change the properties of the metal. Low-alloy steels commonly include manganese, molybdenum, and nickel.

manganese

A hard, brittle, gray-white metal often included in electrodes and flux. Manganese acts as a deoxidizer and increases strength and hardness in the weld.

manipulator

An SAW machine with a boom and a column that allow the welding head to move in all directions. Manipulators are used for automatic SAW.

molybdenum

A hard, silver-white, metal that is strong and corrosion resistant. Molybdenum is often added to electrodes to increase strength and hardness without decreasing ductility.

neutral flux

A type of SAW flux that does not produce significant changes in the composition of weld metal, even when voltage changes drastically. Neutral flux is recommended for most SAW applications, particularly for multi-pass welds.

nickel

A hard, silver-white metal that is easily manipulated. Nickel is often used in alloys.

nickel alloy

A metal made of a combination of nickel and at least one other metal. Nickel alloys often have increased strength, toughness, and impact resistance.

nitrogen

A colorless, odorless, tasteless gas that naturally makes up 78% of breathable air. Nitrogen can ruin a weld bead, so electrodes often contain elements to de-nitrify the molten metal.

open arc welding

An arc welding process that leaves the electric arc exposed. Most arc welding processes are types of open arc welding.

operating factor

The amount of arc-on time in an eight-hour day, which is typically expressed as a percentage. A high operating factor allows a welding process to deposit more filler metal in less time.

oxides

A chemical compound containing oxygen and one other element. Oxides can cause weld defects if they are not removed from a workpiece.

oxygen

A colorless, odorless, tasteless gas that naturally exists in the atmosphere. Oxygen can cause cracking, porosity, and rusting in welded metals.

personal protective equipment

PPE. Any clothing or device worn to minimize exposure to hazards and prevent injury. Personal protective equipment for welding includes welding helmets, long sleeves, and gloves.

plain carbon steel

A type of steel that contains less than 3% alloying elements. Plain carbon steel is considered the most basic type of steel.

porosity

A discontinuity characterized by the appearance of tiny voids in a weld bead, resulting from trapped gases in a material. Excessive porosity can weaken a weld.

post-weld heat treatment

PWHT. The process of heating a weld after welding is complete. Post-weld heat treatment reduces stress in the welded metal.

pounds per square inch

psi. A unit used to measure pressure in the English system. The pounds per square inch unit measures the amount of load pressure that is applied over an area of one square inch.

power source

The device that provides the electricity needed to perform arc welding. SAW systems typically use inverter power sources.

pressure vessels

A closed container designed to hold liquids or gases at high pressures. Pressure vessels include propane tanks.

Safety Data Sheet

SDS. A mandatory document containing hazard information that must accompany almost every chemical in the workplace. A Safety Data Sheet consists of several sections that detail information such as the hazards, precautions, and first aid procedures associated with the chemical.

SAW

Submerged arc welding. An arc welding process that uses a consumable wire electrode and a layer of flux over the weld to shield the arc. SAW, also known as subarc welding, has no visible arc and produces a clean, spatter-free weld.

scavenging elements

A material that cleanses and purifies the weld puddle while it is still in a molten condition. Scavenging elements can help improve the quality of the finished weld.

semi-automatic SAW

A mode of SAW in which an operator manipulates a welding gun to guide the electrode. Semi-automatic SAW is less popular than automatic SAW because it provides slower deposition rates.

side beam

A horizontal beam that supports the travel carriage and welding head. The welding head moves along the side beam to track the electrode along the joint.

silicon

A nonmetallic material that is often present in arc welding electrodes and flux. Silicon acts as a deoxidizer.

silicon-killed steel

A type of steel with a silicon content of more than 0.10% percent. Silicon-killed steel is used in some SAW electrodes.

slag

Cooled flux that forms on top of the weld bead. Slag protects the cooling metal and is chipped off after the weld puddle cools.

spatter

Liquid metal droplets expelled from the welding process. Spatter can leave undesirable dots of metal on the surface of a workpiece.

stainless steel

A type of steel that contains at least 10.5% chromium and exhibits excellent hardness and corrosion resistance. Stainless steel can be welded with many different welding processes.

steels

An alloy of iron and carbon containing less than 2.0% carbon. Steel often contains other elements to enhance various properties of the metal.

subarc welding

An arc welding process that uses a consumable wire electrode and a layer of flux over the weld to shield the arc. Subarc welding, also known as submerged arc welding (SAW), has no visible arc and produces a clean, spatter-free weld.

submerged arc welding

SAW. An arc welding process that uses a consumable wire electrode and a layer of flux over the weld to shield the arc. Submerged arc welding, also known as subarc welding, has no visible arc and produces a clean, spatter-free weld.

tensile strength

A material's ability to resist forces that attempt to pull it apart or stretch it. Tensile strength is usually expressed in pounds per square inch (psi) or in kilopascals (kPa).

transformer

A device that uses magnetic induction to transfer electrical energy from one circuit to another without changing the frequency. Transformers are often used with rectifiers in welding power sources.

transformer power sources

A welding machine that uses a transformer to supply electricity to the welding circuit. Transformer power sources are relatively inexpensive but large and inefficient.

travel carriage

A motor-driven device that moves the welding head along the joint. The travel carriage is mounted to the side beam of an SAW machine.

voltage

The electrical force or pressure that causes current to flow in a circuit. Voltage is measured in volts (V).

weld bead

The end product of a joint that has been welded. Weld beads are formed using a variety of different techniques.

weld penetration

The depth to which the arc heat melts the joint below the surface of the base metals. The amount of amperage directly affects weld penetration.

weld puddle

The small area of molten metal that forms during welding. The cooled weld puddle forms the permanent joint.

welding gun

A hand-held welding instrument that conducts electricity and guides the electrode. Welding guns are used in semi-automatic SAW.

welding head

A component with a contact nozzle that holds and positions the electrode during automatic SAW processes. The welding head is attached to a travel carriage that moves it along the joint.

WFS

Wire feed speed. The rate at which the wire electrode is fed through the contact nozzle. WFS is measured in inches per minute or millimeters per minute.

wire feed speed

WFS. The rate at which the wire electrode is fed through the contact nozzle. Wire feed speed is measured in inches per minute or millimeters per minute.

wire feeder

A device that delivers a supply of wire electrode to a welding gun or welding head. A wire feeder may be combined with a flux tank for SAW.

wire reel assembly

A set of components used to hold a coil of wire electrode for delivery to the contact nozzle. A wire reel assembly may be mounted on a travel carriage for submerged arc welding.