What Is Industrial Welding? Processes, Codes, and Applications
Industrial welding is the joining of metal in structures, pressure equipment, and piping that operate in industrial service. It is typically done to a qualified written procedure, by a qualified welder, under a code that sets inspection and acceptance requirements. This guide explains the main industrial welding processes, how to choose between them, the codes that govern them, and how the welds are inspected.
What Is Industrial Welding?
Industrial welding is the process of joining metal components for structures, pressure equipment, and piping used in industrial service, such as pipelines, pressure vessels, and power plant components. It is typically performed to a written procedure that has been qualified by testing, by a qualified welder, and under a governing code that defines inspection and acceptance.
Industrial welding is not a single process. It draws on several arc welding processes, and what makes a weld industrial is the framework around the process. This guide uses the term for welding done within that framework.
How Does Industrial Welding Differ From General Welding?
The difference is the framework, not the equipment. Industrial welds are made under a code, and the code controls how the procedure and the welder are qualified and how the finished weld is inspected and accepted.
- A governing code applies. The American Welding Society (AWS) D1.1 code covers structural steel, and the American Petroleum Institute (API) Standard 1104 covers pipelines and related facilities.
- The welding procedure is qualified. Section IX of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) contains the rules for qualifying welding procedures that other BPVC sections require.
- The welder is qualified. ASME Section IX covers the qualification of welders and welding operators, and AWS D1.1 includes welder qualification requirements.
- Inspection and acceptance criteria are defined. AWS D1.1, for example, includes inspection methods and weld acceptance criteria.
What Are the Main Industrial Welding Processes?
The main industrial welding processes are shielded metal arc welding (SMAW), gas metal arc welding (GMAW), flux-cored arc welding (FCAW), gas tungsten arc welding (GTAW), and submerged arc welding (SAW). All five are arc welding processes, meaning they use an electric arc as the heat source. They differ in how the weld is shielded from the atmosphere and how filler metal is supplied.
| Process | How it works | Where it is used | Main limits |
|---|---|---|---|
| SMAW (stick) | A flux-coated consumable electrode carries the arc. The coating burns to release shielding gas and forms slag over the weld. | Maintenance and repair work, and thick structural steel with low-hydrogen electrodes such as E7018. | Requires considerable operator skill. Low-hydrogen electrodes must be stored in a heated, low-humidity environment and reconditioned before use. |
| GMAW (MIG) | A continuously fed solid wire is the filler metal. Shielding gas, commonly argon, CO2, or an argon/CO2 mix, protects the weld. | Indoor fabrication where weld appearance matters. | Wind can disturb the shielding gas, which limits outdoor use. |
| FCAW | A tubular wire with a flux core is fed continuously. In the self-shielded form, the flux produces the shielding gas. The gas-shielded form adds an external gas. | Heavy industrial fabrication (gas-shielded form) and outdoor work (self-shielded form). | Leaves slag that must be chipped off. Overhead is the most difficult position. |
| GTAW (TIG) | A non-consumable tungsten electrode carries the arc under an inert shielding gas, usually argon. The welder feeds filler rod by hand into the weld pool. | Work that needs close heat control, including aluminum and alloy steels. | Requires fine precision, does not tolerate contamination, and excess heat can burn through thin material. |
| SAW | A continuously fed wire is welded under a blanket of granular flux, so the arc is buried and not visible. | Pressure vessel fabrication, shipbuilding, and offshore rig welding, on carbon steel, stainless steel, and some nickel alloys from about 1/2 to 5 inches thick. | Limited to flat and horizontal positions. Requires a larger upfront equipment investment. |
Other processes exist as well. Laser welding uses a concentrated beam of light as its heat source and is used in industries including automotive, medical, and aerospace. For a closer comparison of two of the most common arc processes, see WH Labs’ article on the differences between SMAW and GMAW.
How Do You Choose an Industrial Welding Process?
Process selection depends on the base metal and thickness, the welding position, the environment, the governing code or specification, and the required deposition rate. On code work, the choice is recorded in the welding procedure specification (WPS), which must be qualified before it is used.
| Situation | Process to consider | Reason |
|---|---|---|
| Thick plate in the flat or horizontal position, high deposition rate | SAW | Best suited to material from about 1/2 to 5 inches thick, with high deposition rates, but only in flat and horizontal positions. |
| Heavy industrial fabrication | Gas-shielded FCAW | The gas-shielded form is common in heavy industrial fabrication and manufacturing. |
| Outdoor work or wind exposure | Self-shielded FCAW | The flux generates its own shielding gas, so wind is less likely to disturb the weld protection than with GMAW. |
| Indoor fabrication where weld appearance matters | GMAW | Flux-cored welds are often less visually refined than GMAW welds. |
| Thin material or alloys needing close heat control | GTAW | Offers fine control of heat input, but requires clean surfaces and a skilled operator. |
| Vertical or overhead joints | FCAW with reduced settings | SAW cannot be used out of position. Overhead is the most difficult FCAW position, and settings are typically reduced. |
What Codes and Qualifications Govern Industrial Welding?
Industrial welding is governed by codes that match the product being built. AWS D1.1 covers structural steel, API 1104 covers pipelines and related facilities, and ASME Section IX supplies qualification rules that other sections of the ASME Boiler and Pressure Vessel Code require. These codes define how procedures and welders are qualified, and some also set inspection methods and acceptance criteria.
| Code | What it covers |
|---|---|
| AWS D1.1 Structural Welding Code, Steel | How structural steel is welded, qualified, and inspected, including procedure qualification, welder qualification, fabrication and workmanship, inspection methods, and weld acceptance criteria. |
| ASME BPVC Section IX | Rules for the qualification of welding, brazing, and fusing procedures and of welding personnel, including welders and welding operators. |
| API Standard 1104 | Requirements for gas and arc welding used in the construction and in-service repair of pipes and components in pipelines carrying crude oil, petroleum products, fuel gases, carbon dioxide, and nitrogen. |
Qualification happens at two levels. A welding procedure specification (WPS) is a document that describes how to make a weld, including materials, positions, and voltages. A procedure qualification record (PQR) is a formal record of a test weld that was made and tested, and it backs up the WPS. A welder performance qualification (WPQ) then tests whether an individual welder can deposit sound welds using an approved procedure. WH Labs explains the testing behind this in its guide to weld procedure qualification testing.
How Are Industrial Welds Inspected and Tested?
Industrial welds are examined by visual inspection and non-destructive testing (NDT) methods such as liquid penetrant, magnetic particle, ultrasonic, and radiographic testing, which check the finished weld without damaging it. Destructive tests on qualification coupons measure mechanical properties. A code such as AWS D1.1 specifies inspection methods and acceptance criteria.
What each method can and cannot find is covered in WH Labs’ guide to weld integrity testing methods. WH Labs provides weld testing and non-destructive testing alongside its welding work.
What Materials and Industries Use Industrial Welding?
Industrial welding is applied to carbon steel, stainless steel, duplex stainless steel, aluminum, titanium, and nickel alloys such as Inconel. It is used in industries such as oil and gas, chemical processing, power generation, petrochemical, and marine and offshore, on items including pipelines, pressure vessels, storage tanks, and power plant components.
Material affects the process choice. For example, SAW is used on carbon steels, stainless steels, and some nickel alloys, while GTAW is used on materials including aluminum and alloy steels.
What Hazards Does Industrial Welding Involve?
The Occupational Safety and Health Administration (OSHA) lists exposure to metal fumes and ultraviolet (UV) radiation among the health hazards of welding, cutting, and brazing. Safety hazards include burns, eye damage, electrical shock, cuts, and crushed toes and fingers. OSHA publishes hazards and solutions guidance for welding operations on its website.
Frequently Asked Questions
What is industrial welding in simple terms?
Industrial welding is welding done on structures, pressure equipment, and piping used in industry, under a code and a qualified procedure. The finished welds are inspected against defined acceptance criteria. The processes are arc welding processes such as GMAW, GTAW, and SMAW.
Is arc welding the same as industrial welding?
No. Arc welding is a family of processes that use an electric arc as the heat source, including SMAW, GMAW, FCAW, GTAW, and SAW. Industrial welding describes welding done under a code and a qualified procedure, and arc welding processes are commonly used for it.
What is the difference between MIG and flux-cored welding?
MIG welding (GMAW) feeds a solid wire and uses an external shielding gas such as argon, CO2, or an argon/CO2 mix. Flux-cored welding (FCAW) feeds a tubular wire with a flux core. In the self-shielded form, the flux produces the shielding gas, which makes the weld less sensitive to wind, but it leaves slag that must be chipped off.
Which welding process is used for thick steel plate?
Submerged arc welding is best suited to material from about 1/2 to 5 inches thick and has high deposition rates, but it is limited to flat and horizontal positions. Gas-shielded flux-cored welding is also common in heavy industrial fabrication. On code work, the qualified welding procedure determines which process is used.
Does industrial welding require qualified welders?
Code-governed welding generally does. ASME Section IX includes rules for qualifying welders and welding operators, and AWS D1.1 includes welder qualification requirements. A welder performance qualification tests whether an individual can deposit sound welds using an approved procedure.
Welding and Fabrication at WH Labs
WH Labs performs welding at its own facility using GTAW, GMAW, FCAW, SAW, and SMAW, along with overlay welding and hardfacing, on materials including carbon steel, duplex stainless steel, titanium, aluminum, and Inconel. See the full scope on the welding and fabrication services page, or get a free quote for your project.
