Bolts · DIN 933
DIN 933 Hex Bolt
Accurate Fastners manufactures DIN 933 Hex Bolts in stainless steel grades SS 202, SS 304 and SS 316, covering diameters from M3 to M24 and lengths from 6 mm to 150 mm. Each bolt is cold forged to the DIN 933 standard, providing a consistent hexagon head and full metric thread across the entire shank.
- Standard
- DIN 933
- Grades
- 304 / 316 / 202
- Size
- M3 – M24
- Length
- 6 mm – 150 mm
Overview
What is the DIN 933 Hex Bolt?
DIN 933 is a widely recognised German Institute for Standardisation specification for fully threaded hexagon head bolts with a metric coarse thread. The standard defines precise dimensional relationships between the head across-flats width, head height, shank diameter and thread pitch, ensuring that bolts produced by different manufacturers remain interchangeable within the same standard. Accurate Fastners produces these bolts in stainless steel, making them suitable for assemblies where the base material or environment may affect carbon-steel fasteners.
The defining design characteristic of a DIN 933 bolt is that the thread runs the full length of the shank, from directly under the head to the chamfered tip. This distinguishes it from partially threaded variants such as DIN 931. The hexagon head is driven externally by a spanner or socket, providing high torque transfer relative to the contact area and making the bolt easy to install with standard tooling commonly found in fabrication and assembly workshops.
Accurate Fastners cold forges these bolts rather than machining them from bar stock, a process that aligns the grain structure of the stainless steel with the bolt geometry. Cold forging typically produces a work-hardened surface layer and close dimensional repeatability across production runs. The quality control team carries out checks during both procurement of raw material and at the point of despatch, helping to maintain dimensional conformity with the DIN 933 specification across the available size range.
In Depth
Product description
Construction and Geometry
A DIN 933 bolt comprises three main elements: the hexagon head, a short unthreaded bearing face beneath the head, and a fully threaded cylindrical shank terminating in a chamfered point. The across-flats dimension of the head is proportionally larger than the nominal bolt diameter, distributing clamping load across the bearing surface and resisting pull-through in standard clearance holes.
Thread form is metric coarse to ISO 68-1, meaning the pitch is standardised for each diameter, for example 0.5 mm at M3 and 3.0 mm at M24. The chamfered tip helps locate the bolt in a tapped hole or nut before engagement, reducing the likelihood of cross-threading during assembly. Accurate Fastners supplies these bolts in diameters from M3 to M24 and lengths from 6 mm to 150 mm.
Functional Behaviour in an Assembly
Because the thread extends to the underside of the head, a DIN 933 bolt can grip a tapped hole across the full available depth, which is useful when the clamped components are thin or when thread engagement length needs to be maximised. When used with a nut and washer, the fully threaded shank allows the effective clamping length to be adjusted by varying how much of the shank passes through the joint.
The external hex drive transmits torque efficiently and resists cam-out, provided the spanner or socket is correctly sized. Stainless steel has a lower modulus of elasticity than carbon steel, so joint designers may account for this when specifying preload. Galling is a known consideration with stainless fasteners; applying an appropriate lubricant or anti-seize compound during assembly is commonly recommended practice.
How DIN 933 Differs from Similar Fasteners
The closest related standard is DIN 931, which specifies a partially threaded hexagon bolt of the same head geometry. DIN 931 is typically preferred when a plain shank is required to locate components accurately or to provide a shear-resisting section, whereas DIN 933 is used where full thread engagement along the entire joint depth is needed. Both share the same head dimensions for a given diameter, so tooling requirements are identical.
ISO 4017 is the international equivalent of DIN 933 and shares essentially the same dimensions; parts manufactured to one standard are generally interchangeable with those made to the other. Compared with socket head cap screws, the hex bolt offers a wider bearing surface under the head and does not require a hex key, making it more accessible in field or workshop environments where Allen keys may not be readily available.
Material & Grade
Material and grade information
- SS 304
- SS 316
- SS 202
Accurate Fastners offers DIN 933 Hex Bolts in three stainless steel grades: SS 202, SS 304 and SS 316. SS 304 is an austenitic grade containing approximately 18% chromium and 8% nickel and is among the most commonly specified stainless alloys for general industrial use. It offers good corrosion resistance in many non-chloride environments and is widely available, making it a practical choice for a broad range of indoor and moderate outdoor assemblies.
SS 316 adds molybdenum to the alloy, which generally improves resistance to pitting and crevice corrosion in chloride-containing environments compared with SS 304, making it a common selection for coastal, marine-adjacent or chemical-exposure conditions. SS 202 is a lower-nickel, higher-manganese austenitic grade that may be considered for cost-sensitive applications where the environmental conditions are less aggressive. The most appropriate grade for a specific application should be confirmed with the Accurate Fastners sales team based on 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 | Bolt – DIN 933 Hex Bolt |
|---|---|
| Material | Stainless steel |
| Material grade | SS 304, SS 316, SS 202 |
| Applicable standard | DIN 933 |
| Nominal diameter / size | M3 – M24 |
| Length | 6 mm – 150 mm |
| Thread type | Metric, fully threaded |
| Head / form | Hexagon head |
| Drive / tightening | External hex (spanner / socket) |
| Manufacturing process | Cold forged |
Sizes
Available sizes
Documented size range
M3 – M24
Documented length range
6 mm – 150 mm
Individual sizes within the documented range, thread pitches and lengths are confirmed at quotation stage.
Applications
Industrial applications
Water Treatment Equipment
DIN 933 bolts in SS 304 or SS 316 may be used in RO water purifier frames, pressure vessel flanges and filter housings, where contact with treated water makes corrosion resistance a relevant consideration.
Submersible Pump Assemblies
Fully threaded hex bolts are commonly used to secure pump casings, motor end shields and bracket assemblies, where the full thread engagement of DIN 933 assists in maintaining joint integrity in vibrating installations.
Solar Energy Mounting Structures
M8 to M16 DIN 933 bolts are frequently used in solar panel racking systems to join aluminium or steel structural members, with SS 304 typically selected for rooftop applications exposed to weather.
Food and Beverage Machinery
SS 316 DIN 933 bolts may be specified for food processing equipment frames and guards, where hygiene requirements and cleaning agents make higher corrosion resistance a relevant factor in grade selection.
Pharmaceutical Machinery
Pharmaceutical equipment enclosures and conveyor frames may use stainless DIN 933 bolts where surface finish, material traceability and resistance to cleaning chemicals are important assembly considerations.
Featured for: Submersible Pump, Solar Energy, Food & Beverage
Features & Selection
Features and selection considerations
Design features
Fully Threaded Shank
Thread runs the complete length from tip to head, maximising engagement depth in tapped holes and allowing flexible clamping-length adjustment when used with a nut.
Cold Forged Production
Cold forging aligns the grain structure with the bolt profile and produces a work-hardened surface, contributing to dimensional consistency across the production run.
External Hex Drive
Standard across-flats hexagon head is compatible with open-ended spanners, ring spanners and socket drives, requiring no specialist tooling for installation or removal.
Wide Size Range
Available from M3 to M24 in diameter and 6 mm to 150 mm in length, covering a broad span of light-duty to medium structural assembly requirements.
Three Stainless Grades
Offered in SS 202, SS 304 and SS 316, providing options across different corrosion-resistance requirements and budget considerations within a single product line.
Before you order
Thread and Diameter
Confirm nominal diameter and pitch match the mating nut or tapped hole. DIN 933 uses metric coarse thread; verify no fine-pitch variant is required for your application before ordering.
Length and Grip
Measure total joint thickness and add sufficient length for full nut engagement or tapped-hole depth. Because DIN 933 is fully threaded, no plain shank section is available to act as a location feature.
Grade Selection
Choose between SS 202, SS 304 and SS 316 based on the service environment, exposure to moisture or chemicals, and budget. Consult the Accurate Fastners sales team if the operating conditions are uncertain.
Documentation and Quantity
For larger orders or projects requiring material traceability, discuss certification and test report requirements with the sales team at the time of enquiry to ensure documentation is prepared accordingly.
FAQs
Frequently asked questions
What does 'fully threaded' mean in the context of DIN 933?
It means the metric thread extends along the entire length of the shank, from just beneath the head to the chamfered tip. This differs from DIN 931, where a plain unthreaded shank section occupies part of the bolt length.
Which stainless steel grades are available for DIN 933 Hex Bolts from Accurate Fastners?
Accurate Fastners supplies DIN 933 Hex Bolts in SS 202, SS 304 and SS 316. Each grade offers different corrosion resistance characteristics; the sales team can assist in identifying a suitable grade for your environment.
What size range is available?
Accurate Fastners offers DIN 933 Hex Bolts in diameters from M3 to M24 and lengths from 6 mm to 150 mm. If a specific combination within this range is required in quantity, please confirm availability when submitting your enquiry.
Is DIN 933 interchangeable with ISO 4017?
ISO 4017 is the international equivalent standard and shares essentially the same dimensional requirements as DIN 933. Parts produced to either standard are generally interchangeable, though it is advisable to confirm the standard required for your application.
What complementary fasteners are typically used with a DIN 933 Hex Bolt?
A DIN 933 bolt is commonly paired with a DIN 934 hexagon nut and a DIN 125 plain washer or DIN 127 spring washer. Accurate Fastners supplies nuts and washers in matching stainless grades; enquire to confirm current availability.
How can I request a quotation for DIN 933 Hex Bolts?
You may submit your requirements via the enquiry form on the website, email the team directly at export@accuratefastners.com, or reach out on WhatsApp. Please include the diameter, length, grade, quantity and any documentation requirements.
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