Nuts · UNI 5587
UNI 5587 Hex Thick Nut
The UNI 5587 Hex Thick Nut is a cold-forged, increased-height hexagon nut manufactured to the Italian UNI 5587 standard. Accurate Fastners supplies this nut in SS 304 and SS 202 across the M8 to M16 diameter range.
- Standard
- UNI 5587
- Grades
- 304 / 202
- Size
- M8 – M16
- Length
- —
Overview
What is the UNI 5587 Hex Thick Nut?
UNI 5587 is an Italian national standard specifying hexagon nuts with an increased bearing height compared to standard metric hex nuts. The additional height provides a greater number of engaged thread turns, which may distribute clamp load more evenly along the bolt shank. This characteristic makes the thick nut a commonly chosen alternative wherever a standard-height nut might be considered marginal for the application's thread engagement requirement.
Accurate Fastners produces these nuts by cold forging — a process in which stainless steel bar stock is pressed into shape at room temperature rather than machined from solid. Cold forging typically refines the grain structure of the metal, which may contribute to consistent mechanical properties throughout the nut body. The external hex drive profile follows the UNI 5587 geometry, allowing use with standard open-end, ring, or socket spanners across the M8 to M16 range.
The internal thread is metric and follows the standard coarse-pitch series associated with each diameter in the M8–M16 range. The hexagon form with increased height distinguishes UNI 5587 from ordinary flat hex nuts (such as UNI 5588 or ISO 4032) and from heavy hex or coupling nuts. Accurate Fastners' quality control team performs checks during procurement and at the point of delivery to support dimensional consistency across batches.
In Depth
Product description
Construction and Geometry
The UNI 5587 nut is defined by its hexagonal external profile and a body height that exceeds that of a standard ISO metric hex nut. The increased axial length directly increases the number of thread turns in contact with the mating bolt, which may reduce localised stress concentration at the first engaged thread. Cold forging produces a near-net-shape blank, and the internal metric thread is subsequently tapped to UNI 5587 tolerances.
All sizes in the M8 to M16 range share the same hexagonal drive concept, with wrench flat dimensions scaling in accordance with the standard. The stainless steel grades available — SS 304 and SS 202 — are both austenitic alloys, meaning the nut body is non-magnetic in its annealed state. Surface condition is typical of cold-forged stainless steel unless a specific finish is requested and confirmed with the sales team.
Functional Behaviour in an Assembly
When tightened onto a bolt, the UNI 5587 thick nut develops clamp force through elastic elongation of the bolt and compression of the joint members. The increased height means the thread engagement length is greater than that of a standard nut, which may reduce the risk of thread stripping under axial load. This behaviour is particularly relevant in assemblies using lower-strength or coarser materials for the mating component.
The external hex profile allows torque to be applied with widely available tooling. Because the nut is a through-threaded fastener, it is typically used in conjunction with a bolt or threaded stud of matching pitch and diameter. Washers are commonly placed beneath the nut bearing face to protect the joint surface and distribute the clamp load over a larger area; washer selection should be confirmed based on the specific assembly requirements.
How It Differs from Similar Fasteners
A standard hex nut to ISO 4032 or UNI 5588 has a nominal height of approximately 0.8 times the nominal diameter, whereas the UNI 5587 thick nut has a greater height, providing additional thread engagement without stepping up to a coupling nut or castle nut. This positions the UNI 5587 nut between a standard nut and a heavy hex nut in terms of axial dimension, while retaining the same compact hex profile.
Unlike a flange nut, the UNI 5587 design has no integrated bearing flange, so a separate washer is typically required where face protection is needed. Unlike a nyloc or prevailing-torque nut, the UNI 5587 is a free-spinning nut with no locking feature; locking is achieved through torque, thread friction, or supplementary locking elements if specified by the engineer. Grade and pitch must match the mating fastener.
Material & Grade
Material and grade information
- SS 304
- SS 202
SS 304 is an austenitic stainless steel containing approximately 18% chromium and 8% nickel. It is commonly used in a wide range of indoor and moderate outdoor environments and is a standard choice for food and beverage, pharmaceutical machinery, and general industrial assemblies. SS 304 offers a balance of corrosion resistance, formability, and weldability that makes it a frequently specified grade for hex nuts. Grade suitability for a specific environment should always be verified by the design engineer.
SS 202 is an austenitic stainless steel in which a portion of the nickel content is replaced by manganese and nitrogen. It typically offers lower nickel content than SS 304, which may affect cost and corrosion performance depending on the environment. SS 202 may be considered for less aggressive indoor applications where budget is a factor. For guidance on which grade is appropriate for a given assembly, customers are encouraged to consult Accurate Fastners' sales team with details of the service environment.
Grades shown are those documented for this product in the Accurate Fastners brochure. General material notes are guidance only; confirm grade selection for your environment.
Technical Data
Technical specifications
| Product type | Nut – UNI 5587 Hex Thick Nut |
|---|---|
| Material | Stainless steel |
| Material grade | SS 304, SS 202 |
| Applicable standard | UNI 5587 |
| Nominal diameter / size | M8 – M16 |
| Thread type | Metric internal thread |
| Head / form | Hexagon, increased height |
| Drive / tightening | External hex |
| Manufacturing process | Cold forged |
Sizes
Available sizes
Documented size range
M8 – M16
Documented length range
Not applicable
Individual sizes within the documented range, thread pitches and lengths are confirmed at quotation stage.
Applications
Industrial applications
Solar Energy Mounting Structures
Hex thick nuts are commonly used in solar panel racking assemblies where consistent thread engagement under sustained outdoor loading is sought. SS 304 is a frequently specified grade for such structural connections.
Food and Beverage Machinery
Increased-height nuts may be used in frame and panel assemblies on food processing equipment, where SS 304 is often preferred for its corrosion resistance in wet or wash-down environments.
Pharmaceutical Machinery
Stainless steel thick nuts find use in pharmaceutical equipment frames and guards, where material traceability and surface condition are commonly reviewed as part of equipment qualification.
Submersible Pump Assemblies
Pump housings and motor end-bell assemblies may use thick nuts where greater thread engagement is needed to secure bolted flanges subject to vibration or hydraulic pressure during operation.
LED Lighting Structures and Enclosures
Structural brackets and enclosure frames for commercial LED lighting installations may use UNI 5587 thick nuts to secure mounting hardware, particularly where the bolt thread protrusion is limited.
Features & Selection
Features and selection considerations
Design features
Increased Body Height
The UNI 5587 specification defines a greater axial height than a standard hex nut, providing more thread engagement turns and potentially improved load distribution along the bolt thread.
Cold Forged Construction
Cold forging refines the metal grain structure during forming, which may contribute to consistent hardness and dimensional repeatability across a production batch compared to machined equivalents.
Standard External Hex Drive
The hexagonal profile is compatible with common open-end, ring, and socket spanners, requiring no specialist tooling for installation or removal in the field or on the assembly line.
Metric Internal Thread
Metric coarse-pitch internal thread in M8 to M16 ensures compatibility with the widely used ISO metric bolt and stud range, simplifying fastener selection within a metric assembly.
Available in Two Stainless Grades
Supply in SS 304 and SS 202 allows customers to select the grade that aligns with their corrosion environment and cost requirements. Grade confirmation with the sales team is recommended.
Before you order
Diameter and Pitch
Confirm the nominal diameter (M8 through M16) and thread pitch required by the assembly. The nut pitch must match the mating bolt or stud. Coarse pitch is standard; contact the sales team if a specific pitch is needed.
Material Grade
Choose between SS 304 and SS 202 based on the service environment and corrosion exposure. SS 304 is typically preferred for wet or chemically active settings; SS 202 may suit drier, less aggressive indoor conditions.
Mating Fastener and Washer
Specify the corresponding bolt or threaded stud standard and any washers required beneath the nut face. Mismatched thread forms or grades in the same joint may affect assembly performance and should be reviewed.
Quantity and Documentation
Provide required quantities and any documentation needs — such as material test reports or batch certifications — when requesting a quotation. Accurate Fastners' quality team performs checks during procurement and delivery.
FAQs
Frequently asked questions
What does the UNI 5587 standard specify for hex thick nuts?
UNI 5587 is an Italian standard defining hexagon nuts with an increased body height relative to standard metric hex nuts. The greater height provides additional thread engagement length and a distinct dimensional profile compared to ISO 4032 or similar standard-height nut specifications.
Which material grades are available for the UNI 5587 Hex Thick Nut from Accurate Fastners?
Accurate Fastners supplies UNI 5587 Hex Thick Nuts in SS 304 and SS 202. Both are austenitic stainless steel grades. For guidance on which grade suits your application environment, please contact the sales team with details of your service conditions.
What size range is available?
The UNI 5587 Hex Thick Nut is available from M8 to M16. If you require sizes outside this range, contact Accurate Fastners' sales team to discuss whether alternative options can be accommodated or sourced.
How does this nut differ from a standard ISO metric hex nut?
The UNI 5587 thick nut has a greater axial height than a standard ISO 4032 hex nut. This increased height results in more thread turns in engagement with the mating bolt, which may be beneficial where higher thread engagement length is desired in an assembly.
What complementary fasteners are typically used with UNI 5587 thick nuts?
These nuts are commonly paired with metric hex bolts, socket head cap screws, or threaded studs of matching diameter and pitch. Flat or spring washers are often used beneath the nut bearing face. Accurate Fastners supplies a broad range of complementary stainless steel fasteners.
How can I request a quotation for UNI 5587 Hex Thick Nuts?
You can submit an enquiry through the website enquiry form, email the team at export@accuratefastners.com, or reach out via WhatsApp. Please include diameter, quantity, required grade (SS 304 or SS 202), and any documentation requirements to receive an accurate quote promptly.
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