How to Write a Fastener Specification
A fastener specification must let any qualified supplier ship exactly the same part. Every element that affects fit, strength or corrosion has to be stated.
Minimum elements
| Element | Example |
|---|---|
| Product and dimensional standard | Hex cap screw, ASME B18.2.1 |
| Size and thread | 1/2-13 UNC-2A |
| Length | 2 in |
| Material / grade | SAE J429 Grade 5 |
| Finish | Zinc, ASTM F1941 Fe/Zn 8, Type V (trivalent) |
| Quality requirements | Certs (EN 10204 3.1), lot traceability, sampling (ASTM F1470) |
| Packaging and labeling | Quantity per box, label content |
These tables carry the same figures as the printed sheet below.
The printed sheet

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Text version of this sheet
How to write a fastener specification
What it is
AT A GLANCE
SPEC
A fastener specification must let any qualified supplier ship exactly the same part. Every element that
affects fit, strength or corrosion has to be stated.
A spec is a complete sentence
Minimum elements
Element
Example
Product and dimensional standard
Hex cap screw, ASME B18.2.1
Size and thread
1/2-13 UNC-2A
Length
2 in
Material / grade
SAE J429 Grade 5
Finish
Zinc, ASTM F1941 Fe/Zn 8, Type V (trivalent)
Quality requirements
Certs (EN 10204 3.1), lot traceability, sampling (ASTM F1470)
Packaging and labeling
Quantity per box, label content
Key points
Do not mix incompatible requirements (for example A490 with electroplating).
Governing standards: ASME B18.2.1-2012 (R2021); SAE J429 (2014); ASTM F1941/F1941M-16(2025); ASTM F1470-24; EN 10204. Editions shown are the latest confirmed as of
September 2026. The drawing and the governing standard always take precedence over this sheet.
torquing any fastener. Verify the current governing standard, project documents, OEM requirements, size, thread, coating and lot certification. To the fullest extent permitted by law, The Fastener App disclaims liability
arising from reliance on this reference.
Fastener Guide reference FG-240012 · thefastenerapp.com/fastener-guide/specification-control/how-to-write-a-fastener-specification · © The Fastener App. Reference only — verify the current governing standard, drawing and manufacturer data before specifying or installing.

























