What Are Fastener Standards? A Guide to Standards in the Fastener Industry

Huyett Marketing Department
03/30/2023

As industrial engineering progressed throughout the 20th century, many advancements were halted due to factory accidents, mechanical failures, and persistent weaknesses in designs. Forward-thinking engineers began to see the need for standardization within their industries, including everything from safety requirements to material designations.

Enter the emergence of fastener standards. Since fasteners literally hold the industrial world together, it was imperative that engineers use the same language, requirements, and expectations to communicate their fastener needs. The resulting standards for fasteners sparked an ever-growing industry of standard setting, which can be complicated to understand.

So what exactly is a fastener standard, who sets them, and what do they mean?

What is a Fastener Standard?

A fastener standard is usually a document with an explanation of parameters and is a way to communicate the understood requirements or elements of a fastener. When a fastener meets a given standard, that means its characteristics are communicated in a consistent, recognizable fashion.

For example, the American Society of Mechanical Engineers (ASME) produces standards for many different types of fasteners, including dowel pins. The ASME B18.8.2 standard outlines that unhardened ground or hardened ground machine/production pins must meet specific diameter and length tolerances, shapes, surface smoothness, and material, finishing, and treatment requirements. When a dowel pin meets the ASME B18.8.2 standard, all of those requirements are immediately communicated with an assurance of consistency and conformance.

Standards themselves are met with voluntary compliance – there is no legal obligation for manufacturers to exclusively conform to them. However, many OEM designs require fasteners that meet these standards. At times, they are even required by law – for example, all toys sold in the U.S. must meet the ASTM International’s (ASTM’s) F963 safety standard, as required by the Consumer Production Safety Improvement Act.

Failing to comply with some of these standards could cause critical malfunctions and – at times – break the law, which could result in safety violations, injuries, and legal ramifications. It is important to source fasteners from a distributor who offers
a range of standard-compliant parts.

What Does a Fastener Standard Cover?

Fastener standards cover a variety of elements. Dimensions (there are often separate standards for inch fasteners and metric fasteners), mechanical properties, classifications, materials, and usage are all common characteristics. For example, ASTM breaks down their standards into
six different categories, which are helpful in understanding the range of fastener characteristics that are often standardized across other organizations. They are:

Specifications:
Covers physical characteristics like dimensions/tolerances and chemical properties like material composition
Test Methods:
Specifies how to test a property – like machinability – and the desired value of that property
Practice:
Provides procedural instructions for fastener use
Guide:
Offers guidance and considerations for selecting the right fastener
Classification:
Presents information about the fastener without dictating action
Terminology:
Includes definitions, symbols, or other identifying factors of the fastener

Overall, fastener standards aim to create uniform fastener quality by establishing understood baselines for fastener characteristics, manufacturing processes, terminology, and expectations.

Who Sets Fastener Standards?

Fastener standards are mostly set forth by non-profit organizations that standardize products and services so as to set safety, uniformity, and quality expectations. Some seek to establish these expectations on an international or country-specific scale, while others set guidelines for use in industry-specific applications like automotive or military applications.

These organizations do not exclusively handle fasteners – they also deal with procedures, safety guidelines, service expectations, business management, and other products within their focus. However, there are several that produce well-known fastener standards that many manufacturers comply with.

Some of the most common fastener standards organizations are:

ASME
– American Society of Mechanical Engineers
ANSI
– American National Standards Institute
SAE International
– Society of Automotive Engineers
ASTM International
– American Society for Testing and Materials
DIN
– Deutsches Institute for Normung (German National Standards Institute)
ISO
– International Organization for Standardization

The U.S. Department of Defense also designates specific standards that fastener manufacturers must meet in order to do contract work for the military. This includes:

MS
– Military Specification (also seen as
MIL-SPEC, mil specs, MIL-STD,
or
NAS/NASM – the National Aerospace Standard/Military Standard)

Mil spec (meaning military specification) standards are often met through another standard (like an ANSI or SAE standard), but at times they are unique to the military or even a specific military branch.

Let’s take a deeper look at the most common organizations that develop standards for fasteners.

ASME – American Society of Mechanical Engineers

ASME, founded in 1880, is well known for establishing boiler and pressure codes in the early 1900s as a response to critical safety issues. This influenced the safety-oriented nature of their future standards, which cover engineering industries and their equipment designs, construction governance, reporting standards, and more. The standards they set for fasteners range from terminology and definitions to specific clearance hole dimensions for metric threaded fasteners.

Most ASME fastener standards are categories under the
B18
naming system. For example, the
Glossary of Terms for Mechanical Fasteners
standard is categorized as
B18.12
, while the
Fasteners for Use in Structural Applications
standard is known as
B18.2.6
. Other standards include but are not limited to as quoted from
ASME’s Codes & Standards:

B18.2.6 – Fasteners for Use in Structural Applications:
General and dimensional data for metric heavy-hex structural bolts recognized as American National Standard
B18.18.1 – Inspection and Quality Assurance for General Purpose Fasteners:
Quality assurance for internally and externally threaded fasteners and accessories or associated parts
B18.18 – Quality Assurance for Fasteners:
In-process and final inspection requirements for fastener products; receiving inspection plan for fastener purchases
B18.21.1 – Washers:
Helical Spring-Lock, Tooth Lock, and Plain Washers (Inch Series): Dimensional requirements, physical properties, and related testing methods for given fasteners
B18.24 – Part Identifying Number (PIN) Code System Standard for B18 Fastener Products:
Provides users with capability to identify internally, externally, and non-threaded fastener products by pre-selected order of coding as specified

Huyett offers fasteners that comply with the following standards:

B18.15 – Forged
Eye Bolts:
Dimensions and capacities for carbon and stainless steel forged threaded eye bolts of specific sizes for specific materials
B18.22.1 –
Plain Washers:
Incorporated into B18.21.1 standards
B18.3 –
Socket Cap, Shoulder,
Set Screws, and
Hex Keys (Inch Series):
General and dimensional data for various types of relevant hexagon-shaped fasteners
B18.8.1 –
Clevis Pins and
Cotter Pins (Inch Series):
General and dimensional data for clevis and cotter pins of specific sizes.
B18.8.2 –
Taper Pins,
Dowel Pins, Straight Pins,
Grooved Pins, and
Spring Pins (Inch Series):
General and dimensional data for given fasteners

ANSI – American National Standards Institute

ANSI serves to coordinate the creation of standards for a wide variety of industries, from dental to sanitation to health. They don’t actually create the standards themselves – rather, they provide a neutral ground for accrediting other standards organizations like ASME, ASTM, ISO, SAE, and DIN.

Because of this, you will see many ANSI standards listed as a dual name – for example, ANSI accredits ASME’s B18.8.2 standard, so you may see it as
ANSI/ASME B18.8.2
.

If a standard is ANSI accredited, it means that the standard meets the requirements for
openness, balance, consensus,
and
due process
and
adheres to ANSI’s neutral oversight
(according to
ANSI’s Roles). It will be considered an American National Standard (ANS), and will be represented as such to the international community.

Huyett offers a selection of fasteners in compliance with ANSI-accredited ASME standards, including the following as
quoted from ASME’s Codes & Standards:

ANSI/ASME B17.1 –
Keys and Keyseats:
Establishes a uniform relationship between shaft size and key size for parallel and taper keys retaining similar basic sizing
ANSI/ASME B17.2 –
Woodruff Keys and Keyseats:
Covers nomenclature, definitions, ID number, dimensions and tolerances of given fasteners
ANSI/ASME B18.2.2 – Nuts for General Applications: Machine Screw Nuts; and
Hex, Square, Hex Flange, and Coupling Nuts (Inch Series):
General and dimensional data for given fasteners
ANSI/ASME B18.6.3 –
Machine Screws, Tapping Screws, and Metallic Drive Screws (Inch Series):
General and dimensional data for given fasteners

SAE – Society of Automotive Engineers

Beginning in the early 1900s as an effort to standardize the American automobile industry, SAE International is now a global organization that encompasses most any form of mobility, including aerospace, with affiliate organizations in India, Brazil, and China. Their standards cover components, systems, and practices within air and ground vehicle industries, along with medical, defense, and management industries.

To create standards, SAE forms committees of industry experts and follows an
eight-step development process that takes the standard from ideation creation to application improvement. Accepted standards can be found on the
SAE Standards page and will display with its given industry category and current or historical state of existence.

Huyett offers fasteners that meet the following SAE standards as quoted from the
SAE Standards:

J493 – Rod Ends and
Clevis Pins
J534 –
Lubrication Fittings:
Covers general and dimensional specifications for given fasteners

ASTM International – American Society for Testing and Materials

ASTM International started as an American effort to address railroad failures in the early 1900s, out of which came steel standards for rails. Over the century, it expanded to include a wide variety of industries and members from over 140 countries.

Like other organizations, ASTM standards include everything from reporting guidance, safety rules, and equipment maintenance to specific dimensions for specific parts. While ASTM does have
fastener
standards, Huyett complies with ASTM’s
metal
standards in the manufacturing of fasteners. These cover a variety of metals for different uses, shapes, properties, chemical composition, and more.

Huyett offers fasteners that comply with ASTM standards regarding the material they are made from. They include as quoted from the
ASTM Standards Products page:

ASTM A276 – Stainless Steel Bars and Shapes:
Covers hot-finished or cold-finished bars (except for reforging) of multiple shapes
ASTM A29 – General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought:
Covers a group of requirements for carbon and alloy steel bars under several specifications, including cold-finished steel and alloy steel bars
ASTM A295 – High-Carbon Anti-Friction Bearing Steel:
Covers given steel for use in manufacture of anti-friction bearings
ASTM A484 – General Requirements for Stainless Steel Bars, Billets, and Forgings:
General requirements for given materials
ASTM A582 – Free Machining Stainless Steel Bars:
Covers hot or cold-finished bars (except bars for forging) suitable for machining processes
ASTM B16 – Free-Cutting Brass Rod, Bar, and Shapes for Use in Screw Machines:
Covers requirements for any specified cross-section of given material made from Copper Alloy UNS No. C36000 suitable for high-speed screw machining applications
ASTM B221 – Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes:
Covers standard requirements for given materials
ASTM F1145 – Turnbuckles: Swaged, Welded, or Forged:
Covers given fasteners with or without jam nuts (covered in Type 1; Grade 1; Classes B,D,E,F,G, and H)

DIN – Deutsches Institute for Normung (German National Standards Institute)

DIN regulates German standards for a variety of parts and industries, but its first standard – published in 1918, according to the
DIN Timeline – regulated the manufacturing of taper pins. As the organization grew, it encompassed a wider range of standards with a focus on quality assurance. It joined ISO in 1961 after establishing itself as a leading voice in European standards.

Eventually, ISO slowly took over the European role as the international standards representative. Today, DIN standards are usually covered under the ISO, unless an ISO standard does not exist for that given product or service. In that case, it is exclusively a DIN standard. DIN is still widely recognized and used in the international fastener industry because it represented metric standards before the ISO came into being.

Huyett offers fasteners that comply with around 40 DIN standards, which goes beyond the scope of this article to cover completely. However, here are a few common DIN standards Huyett offers as quoted from the
DIN Standards:

DIN 7 (ISO 2338) –
Dowel Pins:
Unhardened steel or austenitic stainless steel
DIN 1469, 1470, 1471, 1472, 1473, 1474, and 1475 –
Grooved Pins
DIN 6880 – Bright Key Steel (for
key stock and machine keys):
Dimensional standards for bars with square, rectangular, or flat rectangular cross sections

We also offer the following fasteners with DIN standard options:
washers, clevis pins, grooved pins, taper pins, spring pins, flat bar stock, machine keys, square bar, grease fittings, eye bolts, dowel pins, retaining rings, woodruff keys, hex keys, hex head bolts, cotter pins, threaded rod, and precision balls.

ISO – International Organization for Standardization

The ISO is perhaps the most well-known standard organization in existence, as it owns almost 25,000 standards in industries ranging from camera film speed to currency codes to social responsibility. It began regulating fasteners about 50 years ago and eventually usurped DIN’s role as Europe’s main standard setter in the industry.

In the fastener realm, many ISO standards originated as DIN standards; such standards may now have different names, but they are essentially the same thing (some slight variations exist). For example,
ISO 133337
used to be known as
DIN 7346
. The two names represent the same standard, which regulates the dimensions of metric light-duty roll pins.

Huyett offers fasteners that comply with the following ISO (and applicable former DIN) standards as directly from the
ISO:

ISO 13337 (DIN 7346) –
Spring-Type Straight Pins – Slotted, Light Duty:
Specifies characteristics of given fasteners made from steel or specific stainless steels
ISO 2341 (DIN 2341) –
Clevis Pins with Heads:
Specifies characteristics of products with specific design elements
ISO 8734 (DIN 6325) –
Parallel Pins of Hardened Steel and Martensitic Stainless Steel (dowel pins):
Specifies characteristics of given fasteners
ISO 8748 (DIN 7344) –
Spring-Type Straight Pins – Coiled, Heavy Duty:
Specifies characteristics of given fasteners made from steel or austenitic/martensitic stainless steel
ISO 8752 (DIN 1481) –
Spring-Type Straight Pins – Slotted, Heavy Duty:
Specifies characteristics of given fasteners made from steel or austenitic/martensitic stainless steel
ISO-2982-2 – Roller Bearings – Accessories – Part 2: Dimensions for
Locknuts and Locking Devices:
Specifies dimensions and tolerances of given fasteners

MS – Military Specification

Military specification – or Mil Spec, mil specs, or MIL-STD – denotes a standard set by the U.S. Department of Defense for military or defense equipment. In many cases, MS uses other standards to define their own. For example, an MS fastener may use an ASTM standard to regulate testing methods, and/or may use an SAE standard to establish material requirements.

In many cases, these fasteners look and behave like their non-MS counterparts. The key differences are the exacting measurements and tolerance required for military use. However, sometimes there is no difference between an MS and non-MS fastener; in these cases, the difference is only whether the manufacturer has certified the fastener’s MS nature or not.

Huyett offers standard dowel pins, flat washers, woodruff keys, slotted spring pins, coiled spring pins, and standard cotter pins in over 300 different MS standard options.

Who Sets Fastener Standards?

Fastener standards help industries communicate fastener requirements and characteristics in a uniform manner that ensures consistency. While they are voluntary, many applications require compliance with certain standards to meet safety or governmental regulations, so it is important to work with a
fastener supplier who distributes a wide range of standard-compliant parts.

For information about the
benefits of becoming a Huyett distributor and the supply chain services we offer, visit our
Supply Chain Simplified resource page or
call or email our Sales Team today.