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Standards and Specifications

A standard as something that is established for use as basis of comparison. There are standards for practically everything that can be measured or evaluated ... from time to materials to processes. Congress created the National Institute of Standards and Technology in 1901 at the start of the industrial revolution to provide the measurements and standards needed to resolve and prevent disputes over trade and to encourage standardization. NIST develops technologies, measurement methods and standards that help US companies compete in the global marketplace. NDT personnel are sometimes required to use calibration standards that are traceable back to a standard held by NIST. This might be a conductivity standard, which can be shown to have the same electrical conductivity as a NIST standard; or it could be a setup standard that was measured with a micrometer that was calibrated using a NIST standard.

A notable development of the twentieth century is the preparation and use of standard specifications to improve the consistency of manufacturing materials and processes, and the resulting products. A specification is a detailed description as to how to produce something or how to perform a particular task. Anytime a product is marked as meeting a specification or a contract requires use of a specification, the product or service must meet the requirements of document. A standard specification is the result of agreement among the involved parties and usually involves acceptance for use by some organization. Standard specifications do not, however, necessarily imply a degree of permanence (like dimensional or volumetric standards), because technical advances in a given field usually calls for periodic revisions to the requirements.

Properly prepared, standards can be of great value to industry. Some of the advantages are:

  • They usually represent the combined knowledge of large group of individuals including producers, consumers and other interested parties, and, thus, reduce the possibility of misinterpretation.
  • They give the manufacturer a standard of production and, therefore, tend to result in a more uniform process or product.
  • They lower unit cost by making standard processes and mass production possible.
  • They permit the consumer to use a specification that has been tried and is enforceable.
  • They set standards of testing and measurement and hence permit the comparison of results.

The disadvantage of standard specifications is they tend to "freeze" practices sometimes based on little data or knowledge, and slow the development of better practices.

Standards always represent an effort by some organized group of people. Any such organization, be it public or private, becomes the standardizing agency. Various levels of these agencies exist, ranging from a single business to local government to national groups to international organizations. The professional and industrial organizations in the United States that lead the development of standards relative to the field of NDT include: the ASTM International, the Society of Automotive Engineers (SAE), the American Iron and Steel Institution (AISI), the American Welding Society (AWS) and the ASME International. Many specifications have also been developed by US government agencies such as the Department of Defense (DOD). However, the US government is downscaling its specification efforts and many military specifications are being converted to specification controlled by industry groups. For example, MIL-I-25135 has historically been the controlling document for both military and civilian penetrant material uses. The recent change in military specification management has lead to the requirement of the Mil specification be incorporated into SAE's AMS 2644 and industry is transition towards the use of this specification.

Generally, the desired tendency is for a given standard to become more uniformly used and accepted. One method of increasing standardization is for a large agency to adopt a standard developed by a smaller one. In the US, thousands of standard specifications are recognized by the American National Standards Institute (ANSI), which is a national, yet private, coordinating agency. At the international level, the International Organization for Standardization (ISO) performs this function. The ISO was formed in 1947 as a non-governmental federation of standardization bodies from over 60 countries. The Unites States is represented within the ISO by the ANSI.

Additional information and links to the standards and specification organizations previously mentioned are provided below.

ASTM International

Partial list of ASTM standards relative to NDT

Link to the
ASTM web site

Founded in 1898, ASTM International is a not-for-profit organization that provides a global forum for the development and publication of voluntary consensus standards for materials, products, systems, and services. Formerly known as the American Society for Testing and Materials, ASTM International provides standards that are accepted and used in research and development, product testing, quality systems, and commercial transactions around the globe. Over 30,000 individuals from 100 nations are the members of ASTM International, who are producers, users, consumers, and representatives of government and academia. In over 130 varied industry areas, ASTM standards serve as the basis for manufacturing, procurement, and regulatory activities.

Each year, ASTM publishes the Annual Book of ASTM Standards, which consists of approximately 70 volumes. Most of the NDT related documents can be found in Volume 03.03, Nondestructive Testing. E-03.03 is under the jurisdiction of ASTM Committee E-7. Each standard practice or guide is the direct responsibility of a subcommittee. For example, document E-94 is the responsibility of subcommittee E07.01 on Radiology (x and gamma) Methods. This committee, comprised of technical experts from many different industries, must review the document every five years and if not revised, it must be reapproved or withdrawn.

The Society of Automotive Engineers (SAE)

Partial list of SAE standards relative to NDT

Link to the
SAE web site

The Society of Automotive Engineers is a professional society that serves as resource for technical information and expertise used in designing, building, maintaining, and operating self-propelled vehicles for use on land or sea, in air or space. Over 83,000 engineers, business executives, educators, and students from more than 97 countries form the membership who share information and exchange ideas for advancing the engineering of mobility systems. SAE is responsible for developing several different documents for the aerospace community. These documents include: Aerospace Standards (AS), Aerospace Material Specifications (AMS), Aerospace Recommended Practices (ARP), Aerospace Information Reports (AIR) and Ground Vehicle Standards (J-Standards). The documents are developed by SAE Committee K members, which are technical experts from the aerospace community.

ASME International

More information on the Boiler & Pressure Vessel Code

Link to the
ASME web site.

ASME International was founded in 1880 as the American Society of Mechanical Engineers. It is a nonprofit educational and technical organization serving a worldwide membership of 125,000. ASME maintains and distributes 600 codes and standards used around the world for the design, manufacturing and installation of mechanical devices. One of these codes is called the Boiler and Pressure Vessel Code. This code controls the design, inspection, and repair of pressure vessels. Inspection plays a big part in keeping the components operating safely. More information about the B&PV Code can be found at the links to the left.

The American Welding Society

Partial list of AWS Standards and Documents relative to NDT

Link to the
AWS web site

The American Welding Society (AWS) was founded in 1919 as a multifaceted, nonprofit organization with a goal to advance the science, technology and application of welding and related joining disciplines. AWS serves 50,000 members worldwide. Membership consists of engineers, scientists, educators, researchers, welders, inspectors, welding foremen, company executives and officers, and sales associates.

The International Organization for Standardization (ISO)

Partial list of ISO standards and documents relative to NDT

Link to the
ISO web site

The International Organization for Standardization (ISO) was formed in 1947 as a non-governmental federation of standardization bodies from over 60 countries. The ISO is headquartered in Geneva, Switzerland. The Unites States is represented by the ANSI.

The Air Transport Association (ATA)

Link to the
ATA web site.

Founded by a group of 14 airlines in 1936, the ATA was the first, and today remains, the only trade organization for the principal US airlines. The purpose of the ATA is to support and assist its members by promoting the air transport industry and the safety, cost effectiveness, and technological advancement of its operations; advocating common industry positions before state and local governments; conducting designated industry-wide programs; and assuring governmental and public understanding of all aspects of air transport. There are two ATA documents that serve as guidelines for the training of inspection personnel.

  • ATA Specification 105, Guidelines for Training and Qualifying Personnel in Non-Destructive Testing
    Methods. This document serves as a guideline for the development of a training program for personnel who accomplish nondestructive testing tasks. While partially derived from more universal training standards such as ASNT SNT-TC-1A and NAS 410, this document is dedicated to preparing a curriculum for an airline's maintenance training program and qualifying individuals to conduct aircraft inspections.
  • ATA Specification 107, Visual Inspection Personnel Training and Qualification Guide for FAR Part 121
    Air Carriers. This document addresses training and qualification needs of the aircraft inspection technician and recommends a minimum list of required inspection items.


The Aerospace Industries Association

Link to the
AIA's web site.

The Aerospace Industries Association represents the nation's major manufacturers of commercial, military and business aircraft, helicopters, aircraft engines, missiles, spacecraft, materials, and related components and equipment. The AIA has been a aerospace industry trade association since 1919. It was originally known as the Aeronautical Chamber of Commerce (ACCA). The AIA is responsible for two NDT related documents, which are:

  • NAS 410, Certification & Qualification Of Nondestructive Test Personnel. This document is a widely used document in the aerospace industry as it replaces MIL-STD-410E: Military Standard, Nondestructive Testing Personnel Qualification and Certification..
  • NAS 999, Nondestructive Inspection of Advanced Composite Structure.

The American National Standards Institute (ANSI)

Link to the
ANSI web site.
ANSI is a private, nonprofit organization that administers and coordinates the US voluntary standardization and conformity assessment system. The Institute's mission is to enhance both the global competitiveness of US business and the US quality of life by promoting and facilitating voluntary consensus standards and conformity assessment systems, and safeguarding their integrity.

US Department of Defense Specifications - A list of DOD specifications (Mil Specs, NAV, Etc.) was not prepared since the trend is to move away from their use and more documents are being canceled or made inactive everyday. Information on DOD specifications can be found at the following web site.

The Department of Defense Single Stock Point for Military Specifications, Standards and Related Publications