Property Class 8.8 Steel Sealing Screws with Bonded Washer are supplied to ISO 898-1 property class 8.8. Corrosion behaviour is requires plating (zinc) for corrosion protection, the material is magnetic, and the usable service range is commonly limited to approx. +300 °C; confirm against the coating and the load. In practice this grade is the workhorse medium-carbon alloy class for structural joints.
- Grade
- ISO 898-1 property class 8.8
- Corrosion resistance
- Requires plating (zinc) for corrosion protection
- Magnetic response
- Magnetic
- Service temperature
- commonly limited to approx. +300 °C; confirm against the coating and the load
Property values are typical for the grade. Certified mechanical test data is available on request for production orders.
Property Class 8.8 Steel Sealing Screws with Bonded Washer are supplied to DIN 933. The grade provides requires plating (zinc) for corrosion protection and is magnetic; the practical service range is commonly limited to approx. +300 °C; confirm against the coating and the load. Property data, grade comparison and the full size table follow.
Why Choose Property Class 8.8 Steel for Sealing Screws with Bonded Washer
The workhorse medium-carbon alloy class for structural joints. For sealing screws with bonded washer, this matters when requires plating (zinc) for corrosion protection is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 898-1 property class 8.8 |
|---|
| Magnetic response | Magnetic |
|---|
| Service temperature | commonly limited to approx. +300 °C; confirm against the coating and the load |
|---|
| Corrosion characteristic | Requires plating (zinc) for corrosion protection |
|---|
Corrosion Behavior in Service
Carbon and alloy steel sealing screws with bonded washer require a coating for corrosion protection. Zinc plating (with or without passivation) is the most common; hot-dip galvanizing is used for outdoor structural service; black-oxide is mainly a tarnish-prevention finish for tool-room use.
Galvanic & Galling Considerations
For sealing screws with bonded washer in steel, the dominant compatibility issue is hydrogen embrittlement at high property classes (10.9 and above) when electroplated. Plating must be followed by an appropriate baking treatment, or a non-electroplated finish (mechanical zinc, zinc flake) should be substituted.
Sizes of Sealing Screws with Bonded Washer Available in Property Class 8.8 Steel
| Thread size | Pitch (mm) | Across flats s (mm) | Head height k (mm) | Seal outer diameter (mm) | Seal thickness (mm) | Common length range (mm) | Reference standard |
|---|
| M5 | 0.8 | 8 | 3.5 | 10 | 1.0 | 8~40 | DIN 933 + BS 4518 |
| M6 | 1.0 | 10 | 4.0 | 12 | 1.5 | 10~50 | DIN 933 + BS 4518 |
| M8 | 1.25 | 13 | 5.3 | 14 | 1.5 | 12~60 | DIN 933 + BS 4518 |
| M10 | 1.5 | 17 | 6.4 | 16 | 1.5 | 16~60 | DIN 933 + BS 4518 |
| M12 | 1.75 | 19 | 7.5 | 19 | 2.0 | 20~80 | DIN 933 + BS 4518 |
| M16 | 2.0 | 24 | 10.0 | 24 | 2.0 | 25~80 | DIN 933 + BS 4518 |
Dimensions are independent of the material: the table above lists the sizes supplied, and on this page every one of them is quoted in Property Class 8.8 Steel. The catalogue's default material column has been omitted here so it cannot be read as contradicting that.
Custom manufacturing · Made to drawing
Need this screw in a grade that is not listed?
Grade 8 8 Steel is one of the grades the catalog describes. Thread size and pitch, length, property class, drive form, head geometry and head marking are all specifiable — the standard part is where it starts, not where it stops. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
Custom screw manufacturingSend a drawing
Applications & Industries
What Sealing Screws with Bonded Washer are specified for, industry by industry. Stocked from M5 to M16.
Industries that specify Sealing Screws with Bonded Washer
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Maintenance & MRO
Stocked replacements matched to an existing property class, thread and finish.
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Food, pharma & cleanroom
Stainless assemblies that are washed down, where the finish matters as much as the strength.
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Machine building & OEM
The default fastener on production equipment: covers, brackets, motor mounts and sub-assemblies tightened to a specified torque.
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Automotive & transport
Chassis, driveline and body fixings that see vibration and are assembled to a controlled preload.
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Steel fabrication
Bolted connections in frames, enclosures, walkways and weldments, on the bench and on site.
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Energy & infrastructure
Tower, pipework, switchgear and plant fixings specified for long service life and inspectable joints.
Typical applications
- assemblies that are dismantled for service and re-torqued
- joints where the property class is stated on the drawing
- clamping two machined faces to a calculated preload
- bolting brackets, motors and gearboxes to a frame
Service conditions to specify against
- Marine and coastal
- Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit.
- High load
- Supplied in ISO 898-1 property classes, so the joint can be designed to a stated proof load and tightened to a calculated torque rather than by feel.
- Sealed joints
- Used where the fixing has to keep water or air out as well as hold — the elastomer, not the fastener, decides service life.
- Torque and preload
- The joint is designed around bolt tension, so lubrication, coating and the friction coefficient all change the torque figure — state them together.
Where to use something else
- Do not use a machine thread into unthreaded sheet or timber; use a tapping screw, rivet nut or insert made for that parent material.
Full application guide: where Sealing Screws with Bonded Washer are used, how to specify them, and the cases they are wrong for
