Welding Codes: Common Codes

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Welding codes are developed by a variety of organizations to set requirements for:

  • inspection
  • testing
  • repair
  • approved materials
  • fabrication
  • design specifications
  • welding itself

Four groups set the foundation for the codes.

Each group sets and adapts codes that pertain to their area of interest.

The most commonly used codes are from the AWS (D1.1) and ASME (Section IX).

The difference between ASME and AWS is that ASME is for welding procedure and welder qualification.

AWS is for both welder and welding procedure qualification including inspection, erection and fabrication.

Contracts may specify one or the other code.

  • American Welding Society (AWS)
  • American Petroleum Institute (API)
  • American Society of Mechanical Engineers (ASME)
  • American Society for Non-Destructive Testing (ASNT)

The codes established by these organizations are then adopted by others such as the Department of Defense.

Codes are also recognized by the American National Standards Institute (ANSI).

The list below is the codes that are used to define requirements for the most common welding processes. Often a work contract will specify the correct code.

welding code aws
The AWS 3.1. welding codes are written for welders, engineers, erectors, fabricators and inspectors that work with or around welded steel structures

Why Welding Codes Exist

The purpose of each of the welding codes is to have a uniform way to approach welding that reflects the best practices developed and proven to work overtime.

They have the effect of improving welder skills, equipment, and processes.

The result is growth in the profession when it comes to skill, quality, and welder efficiency.

Key Terms

  • WPS: A WPS is the welding procedure specification. It shows the welder an overall direction, shows the welding materials and joint design. It also lists important code requirements, techniques, parameters and welding materials.
  • PQR: The PQR is the procedure qualification report. It is a record of testing results for any welds created in accordance with the welding procedure specification (WPS).
  • WQTR: The WQTR or welder qualification test record describes the results of a test to determine if a welder is qualified to weld to a certain welding procedure specification.
  • Code: A standard is a code when it has been adopted by one or more governmental bodies and is enforceable by law, or when it has been incorporated into a business contract.

American Petroleum Institute (API)

The API or American Petroleum Institute is a national trade association that speaks for all aspects of the U.S. oil and natural gas industry.

Welding codes issued are related to tasks such as pipeline inspection, storage tanks and pipeline construction.

API 570: Piping Inspection

Sets requirements for the inspection, alteration, repair and re-rating of in-service piping systems. It was created for the chemical process and petroleum refining industries. It is also broadly applied to piping systems. The code was written for groups that have access to or maintain an authorized inspection agency, a repair group, and technically qualified piping engineers, inspectors and examiners.

API 620: Welded Steel Tanks for Storage

This code standard is for the design, material, erection, fabrication and testing requirements for vertical, cylindrical, above ground, closed and open-top, welded steel storage tanks in various sizes and capacities for internal pressures approximating atmospheric pressure (internal pressure not exceeding the weight of the roof plates), but a higher internal pressure is permitted when additional requirements are met.

This standard applies only to tanks whose entire bottom is uniformly supported and to tanks in non-refrigerated service that have a maximum operating temperature of 90°C (200°F).

API 653: Tank Reconstruction, Alteration, Repair and Inspection

This standard covers carbon and low alloy steel tanks built to API Standard 650 and its predecessor API Specification 12C. API 653 provides minimum requirements for maintaining the integrity of welded or riveted, atmospheric pressure, above ground storage tanks after they have been placed in service. It covers the maintenance inspection, repair, alteration, relocation, and reconstruction of such tanks. The scope of this publication is limited to the tank foundation, bottom, shell, structure, roof, attached appurtenances, and nozzles to the face of the first flange, first threaded joint, or first welding-end connection. This standard employs the principles of API 650; however, storage tank owner/operators may apply this standard to any steel tank constructed in accordance with a tank specification.

API 1104 Welding of Pipelines and Related Facilities

This standard covers the arc and gas welding of fillet, butt, arc and gas, and socket welds in carbon and low-alloy steel piping used in the compression, pumping, and transmission of crude petroleum, petroleum products, fuel gases, carbon dioxide, and nitrogen, and where applicable, covers welding on distribution systems.

It applies to both new construction and in-service welding. The welding may be done by a shielded metal-arc welding, submerged arc welding, gas tungsten-arc welding, gas metal-arc welding, flux-cored arc welding, plasma arc welding, oxyacetylene welding, or flash butt welding process or by a combination of these processes using a manual, semi-automatic, or automatic welding technique or a combination of these techniques, The welds may be produced by position or roll welding or by a combination of position and roll welding.

This standard also covers the procedures for radiographic, magnetic particle, liquid penetrant, and ultrasonic testing as well as the acceptance standards to be applied to production welds tested to destruction or inspected by radiographic, magnetic particle, liquid penetrant, ultrasonic, and visual testing methods.

American Welding Society (AWS)

The American Welding Society (AWS) has a mission to advance the science, technology and application of welding and allied joining and cutting processes, including brazing, soldering, and thermal spraying.

The organization has more than 350 welding codes, procedures, practices and standards.

The standard D1.1 (see below) is referenced more than any other code when it comes to steel welding.

The AWS sets welding codes for the following:

  • Certifying welding inspectors
  • Aluminum welding (gas arc welding, gas tungsten welding, plasma arc welding)
  • Sheet Steel welding: Applications and capacities for sheet metal
  • Aerospace: fusion welding materials and processes
  • Construction: bridge highway welding codes
  • Structural Steel Welding: All types of welding processes

AWS D1.1: Fabricating and Erecting Welded Steel Structures

This code contains the requirements for fabricating and erecting welded steel structures. This code applies to steels with a thickness of 1/8 inch (3.2mm) or more. When this code is specified in a contract, most of the provisions are mandatory. Optional provisions and examples are shown in an annex included within this code.

The code is primarily applied to support structures and buildings, such as erecting and fabricating a structure that is welded.

The code is 540 pages and is organized into eight “clauses” or chapters:

  1. General requirements
  2. Design of welded connections
  3. Pre-qualification of Weld Procedure Specifications (WPS): contains the requirements for exempting a WPS from the WPS qualification requirements
  4. Qualification: requirements for Weld Procedure Specification (WPS) including PQRs (Procedure Qualification Records) and qualification tests for all welding personnel (tack welders, welding operators, welders)
  5. Fabrication and erection requirements applicable to welded structures governed by this code
  6. Inspection
  7. Stud welding: requirements for welding studs to structural steel
  8. Strengthening and Repairing Existing Structures: information pertinent to welded modification or repair of existing structures

AWS D1.2: This is the Structural Welding Code-Aluminum

The welding requirements are applicable to any type of welded aluminum alloy structure.

This code is appropriate for use in the fabrication of supporting structures and appurtenances.

It is not intended to supplant codes developed for use in specialized fabrication such as the ASME Boiler and Pressure Vessel Code, aerospace codes, or military codes.

AWS D1.3: Structural Steel Welding Code

This is the Structural Welding Code-Sheet Steel.

This code covers the arc welding of structural steel sheet/strip steels including cold-formed members which are equal to or less than 3/16 inch (.188 in./4.8mm) in nominal thickness.

Three weld types unique to sheet steel, arc spot, arc seam, and arc plug welds are included in this code.

AWS D1.4: Structural Welding Code for Reinforcing Steel

This is the Structural Welding Code-Reinforcing Steel.

This code shall apply to the welding of reinforcing steel to reinforcing steel and of reinforcing steel to carbon or low-alloy structural steel.

This code shall be used in conjunction with the prescribed general building code specifications and is applicable to all welding of reinforcing steel using the processes listed in Section 1.4, and performed as a part of reinforced concrete construction.

When reinforcing steel is welded to structural steel, the provisions of AWS D1.1 shall apply to the structural steel component.

bridge welding code
The Bridge Welding Codes are designed to avoid hydrogen and fatigue cracks that can impact bridge safety

AWS D1.5: Bridge Welding Code

This is the Bridge Welding Code.

This code covers welding fabrication requirements applicable to welded highway bridges.

It is to be used in conjunction with the AASHTO Standard Specification for Highway Bridges or the AASHTO LRFD Bridge Design Specifications.

This code is not intended to be used for the following:

  • Steels with a minimum specified yield strength greater than 690 MPa (100ksi),
  • Pressure vessels or pressure piping,
  • Base metals other than carbon or low alloy steels, or
  • Structures composed of structural tubing

AWS D1.6: Stainless Steel Structural Welding Code

Structural Welding Code-Stainless Steel. This code covers welding requirements applicable to stainless steel weldments subject to design stress. It shall be used in conjunction with any complementary code or specification for the design or construction of stainless steel weldments.

AWS D3.5-93R: Steel Hull Welding

Guide for Steel Hull Welding. This guide is referenced in many contract specifications for building vessels from barges to tugboats.

AWS D3.6M: Under-water Welding

Specification for Under-Water Welding. ·

AWS D3.7: Aluminum Hull Welding

Guide for Aluminum Hull Welding. Similar to the Steel Hull Welding Guide, but with a special emphasis on the unique properties of aluminum.

AWS D8.8-97: Weld Quality for Light Truck and Auto

Specification for Automotive and Light Truck Weld Quality: Arc Welding.

AWS D14.1: Construction and Earth Moving Equipment

Specification for Welding Earth Moving and Construction Equipment.

Applies to all structural welds used in the manufacture of earthmoving and construction equipment.

This specification reflects the welding practices employed by manufacturers within the industry and incorporates various methods which have been proven successful by individual manufacturers.

AWS D14.5: Press Components and Welding Presses

Specification for Welding Presses and Press Components.

The purpose of this specification is to establish minimum acceptable requirements for weld joint design and the fabrication by welding of presses and press components, and is not intended to apply to material feed mechanisms and tooling.

It shall also apply to the modification or repair by welding of new or existing presses or press components.

American Society of Mechanical Engineers (ASME)

asme code compliance stamp
ASME BPVC “U” Stamp – A Mark Applied to the Name Plate of a Pressure Vessel by an Authorized Shop or other Organization to Indicate that the Vessel has been Fabricated in Accordance with the ASME BPVC Section

ASME is a not-for-profit membership organization that enables collaboration, knowledge sharing, career enrichment, and skills development across all engineering disciplines, toward a goal of helping the global engineering community develop solutions to benefit lives and livelihoods.

The organization has approximately 600 consensus standards developed by over 100 committees. In general, standards address:

  • performance test codes
  • standardization
  • safety
  • nuclear technology
  • pressure technology

Section IX is one of the most commonly used welding codes for qualifying welders.  Section VIII Division 1 is used with section IX when using codes applied to fabrication.

ASME Section I: Requirements for Power boilers

Part PW lists the Requirements for Boilers Fabricated By Welding. The rules in Part PW are applicable to boilers and component parts thereof, including piping constructed under the provisions of this Section that are fabricated by welding and shall be used in conjunction with the general requirements of Part PG as well as with the specific requirements in the applicable Parts of this Section that pertain to the type of boiler under consideration.

Refers to requirements for all methods of construction of:

  • Power, electric, and miniature boilers
  • High-temperature water boilers used in stationary service
  • Power boilers used in locomotive, portable, and traction service.

Includes requirements for:

  • Boilers Fabricated by Welding
  • Boilers Fabricated by Riveting (by reference only)
  • Watertube Boilers
  • Firetube Boilers
  • Feedwater Heaters
  • Miniature Boilers
  • Electric Boilers
  • Organic Fluid Vaporizer Generators

ASME Section II Material Specifications-4 Subparts(A,B,C,D):

  • Subpart A-Ferrous Material Specifications.
  • Subpart B-Non-Ferrous Material Specifications-Materials.
  • Subpart C-Specifications for Welding Rods, Electrodes, and Filler Metals.
  • Subpart D- Properties-divided into three subparts-
  1. Stress Tables.
  2.  Physical Properties Tables.
  3. Charts and Tables for Determining Shell Thickness of Components Under External Pressure.

ASME Section III: Nuclear

There are Three Subdivisions-

  • Division 1-Rules For Construction of Nuclear Facility Components.
  1. Subsection NB lists Class 1 Components.
  2. Subsection NC lists Class 2 Components.
  3. Subsection ND lists Class 3 Components.
  4. Subsection NE lists Class MC Components.
  5. Subsection NF covers Supports.
  6. Subsection NG deals with Core Support Structures.
  7. Subsection NH covers Class 1 Components in Elevated Temperature Service.
  • Division 2: Code For Concrete Reactor Vessels and Containment.
  • Division 3″ Containment Systems for Storage and Transport Packaging of Spent Nuclear Fuel and High Level Radioactive Material and Waste. ·

ASME Section IV: Rules For Construction of Heating Boilers.

The rules to Part HG apply to steam heating boilers, hot water heating boilers, hot water supply boilers, and appurtenances thereto. They shall be used in conjunction with the specific requirements of Parts HF and HC whichever is applicable. The forward provides the basis for these rules. Part HG is not intended to apply to potable water heaters except as provided for in Part HLW.

ASME Section V: Non-Destructive Examination

Unless otherwise specified by the referencing Code Section, or other referencing documents, this Section of the Code contains requirements and methods for nondestructive examination which are Code requirements to the extent they are specifically referenced and required by other Code Sections. These nondestructive examination methods are intended to detect surface and internal discontinuities in materials, welds, and fabricated parts and components. They include radiographic examination, ultrasonic examination, liquid penetrant examination, magnetic particle examination, eddy current examination, visual examination, leak testing, and acoustic emission examination.

ASME Section VI Recommended Rules For the Care and Operation of Heating Boilers

This is divided into nine subsections.

  1. General, covers scope and terminology.
  2. Types of Boilers.
  3. Accessories and Installation.
  4. Fuels.
  5. Fuel Burning Equipment and Fuel Burning Controls.
  6. Boiler Room Facilities.
  7. Operation, Maintenance, and Repair-Steam Boilers.
  8. Operation, Maintenance, and Repair-Hot Water Boilers and Hot Water Heating Boilers.
  9. Water Treatment

ASME Section VII Recommended Guidelines for the Care of Power Boilers

  • Guidelines to promote safety in the use of stationary, portable, and traction type heating boilers.
  • The section provides guidelines to assist operators of power boilers in maintaining their plants as safely as possible.
  • Emphasis has been placed on industrial-type boilers because of their extensive use.
  • Contains Fuels for Routine Operation; Operating and Maintaining Boiler Appliances; Inspection; Prevention of Direct Causes of Boiler Failure; Design of Installation; Operation of Boiler Auxiliaries; Control of Internal Chemical Conditions

ASME Section VIII Pressure Vessel and Tank Code

This is divided into three sub-divisions. Division 1-Subsection A is general pressure vessel information. Subsection B covers the Requirements Pertaining to Methods of Fabrication of Pressure Vessels. Subsection C lists the Requirements Pertaining to Classes of Materials. Division 2 covers Alternative Rules for Construction of Pressure Vessels. Division 3 lists Alternative Rules for Construction of High Pressure Boilers.

ASME Section IX Welding and Brazing Qualifications

This section covers the requirements for Weld Procedure Specifications (WPS), Procedure Qualification Records (PQR), and certification requirements for tackers, welders, welding operators, and brazing personnel.

ASME Section X Fiber-Reinforced Plastic Pressure Vessels

  • Requirements for construction of an FRP pressure vessel in conformance with a manufacturer’s design report. 
  • It includes production, processing, fabrication, inspection and testing methods required for the vessel.

ASME Section XI Rules for In-service Inspection of Nuclear Power Plant Components

  • Rules for the examination, in-service testing and inspection, and replacement and repair of components and systems in light-water cooled and liquid-metal cooled nuclear power plants.

ASME Section XII: Rules for Construction and Continued Service of Transport Tanks

  • Requirements for construction and continued service of pressure vessels for the transportation of dangerous goods via highway, rail, air or water at pressures from full vacuum to 3,000 psig and volumes greater than 120 gallons.

ASME B31.1: Power Piping

This Code prescribes requirements for the design, materials, fabrication, erection, test, and inspection of power and auxiliary service piping systems for electrical generation stations, industrial and institutional plants, central and district heating plants, and district heating systems, except as limited by para. 100.1.3.

These systems are not limited by plant or property lines unless they are specifically limited by para. 100.1. Piping as used in this Code includes pipe, flanges, bolting, gaskets, valves, relief devices, fittings, and the pressure-containing portions of other piping components.

It also includes hangers and supports and other equipment items necessary to prevent over-stressing the pressure-containing components.

The users of this Code are advised that in some areas legislation may establish governmental jurisdiction over the subject matter covered in this Code. However, any such legal requirement shall not relieve the owner of his inspection responsibilities specified in para. 136.1.

ASME B31.2: Fuel Gas Piping-Material

This Code covers the design, fabrication, installation, and testing of piping systems for fuel gases such as natural gas, manufactured gas, liquefied petroleum gas-air mixtures above the upper combustible limit, liquefied petroleum gas in the gaseous phase, or a mixture of these gases.

Included within the scope of this Code are fuel gas piping systems both in buildings and between buildings, form the outlet of the consumer’s meter set assembly (or point of delivery) to and including the first pressure containing valve upstream of the gas utilization device. Piping systems within the scope of this Code include all components such as pipe, valves, fittings, flanges (except inlet and outlet flanges that are a part of equipment or apparatus described in para. 200.1.4), bolting and gaskets. Also included are the pressure-containing parts of other components such as expansion joints, strainer and metering devices, and piping supporting fixtures and structural attachments.

ASME B31.3: Process Piping

Rules for the Process Piping Code have been developed considering piping typically found in chemical, petroleum refineries, pharmaceutical, textile, paper, semiconductor, and cryogenic plants; and related processing plants and terminals.

This Code prescribes requirements for materials and components, design, fabrication, erection, assembly, examination, inspection, and testing of piping. this Code applies to all fluids, including: raw, intermediate, and finished chemicals; petroleum products; gas, steam, air, and water; fluidized solids; refrigerants; and cryogenic fluids.

ASME B31.4: Liquid Transportation Systems for Hydrocarbons, Liquid Petroleum Gas, Anhydrous Ammonia, and Alcohol

This Code prescribes requirements for the design, materials, construction, assembly, inspection, and testing of piping transporting liquids such as crude oil, condensate, natural gasoline, natural gas liquids, liquefied petroleum gas, carbon dioxide, liquid alcohol, liquid anhydrous ammonia, and liquid petroleum products between producers’ lease facilities, tank farms, natural gas processing plants, refineries, stations, ammonia plants, terminals (marine, rail, truck), and other delivery and receiving points. Piping consists of pipe, flanges, bolting, gaskets, valves, relief devices, fittings, and the pressure containing parts of other piping components. It also includes hangers and supports, and other equipment items necessary to prevent over stressing the pressure containing parts.

ASME B31.5:Piping Refrigeration

This Code prescribes requirements for the materials, design, fabrication, assembly, erection, test, and inspection of refrigerant and secondary coolant piping for temperatures as low as -320°F except as specifically excluded.

ASME B31.8 Gas Transmission and Distribution

This code covers the design, fabrication, installation, inspection, testing and safety aspects of operation and maintenance of gas transmission and distribution systems, including gas pipelines, gas compressor stations, gas metering and regulation stations, gas mains, and service lines up to the outlet of the customer’s meter set assembly.

Included within this Code are gas transmission and gathering pipelines, including appurtenances, that are installed offshore for the purpose of transporting gas from production facilities to onshore locations. Much more is also covered in this code.

ASME B31.9 Building Services Piping

This Code Section has rules for the piping in industrial, institutional, commercial and public buildings, and multi-unit residences which does not require the range of sizes, pressures, and temperatures covered in B31.1.

ASME B31.11 Slurry Transportation Piping Systems-This code prescribes minimum requirements for the design, materials, construction, assembly, inspection, testing, operation, and maintenance of piping transporting aqueous slurries of non-hazardous materials, such as coal, mineral ore, concentrates, and other solid material, between a slurry processing plant or terminal, and a receiving plant or terminal.

American Society for Non-Destructive Testing (ASNT Codes)

The American Society for Nondestructive Testing, Inc. (ASNT) is the world’s largest technical society for nondestructive testing (NDT) professionals.

SNT-TC-1A-2011: Recommended Practice No.

SNT-TC-1A: Personnel Qualification and Certification in Non-Destructive Testing 

This program is a guideline to assist employers to establish their own in-house certification program.

It is a set of recommendations for the qualification and certification of NDT personnel.

It also provides recommended educational, experience and training for the NDT methods.

ANSI/ASNT-CP 189-2011: ASNT Standard for Qualification and Certification of Non-Destructive Testing Personnel

This document is a Standard that establishes minimum requirements for the qualification and certification of non-destructive testing and predictive maintenance personnel.

It also details the minimum training, education, and experience requirements for NDT personnel and provides criteria for documenting qualifications and certification

Resource for Welding Codes

Companies like iHS specialize in providing the latest version of over 370 standards developing organizations (called SDOs).

Access to the latest welding codes reduces risk associated with noncompliance and helps to reduce the risk of welding to an outdated standard that does not pass inspection.