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) | Seal material | Common length range (mm) | Reference standard |
|---|---|---|---|---|---|---|---|---|
| M5 | 0.8 | 8 | 3.5 | 10 | 1.0 | NBR | 8~40 | DIN 933 + BS 4518 |
| M6 | 1.0 | 10 | 4.0 | 12 | 1.5 | NBR | 10~50 | DIN 933 + BS 4518 |
| M8 | 1.25 | 13 | 5.3 | 14 | 1.5 | NBR | 12~60 | DIN 933 + BS 4518 |
| M10 | 1.5 | 17 | 6.4 | 16 | 1.5 | NBR | 16~60 | DIN 933 + BS 4518 |
| M12 | 1.75 | 19 | 7.5 | 19 | 2.0 | NBR | 20~80 | DIN 933 + BS 4518 |
| M16 | 2.0 | 24 | 10.0 | 24 | 2.0 | NBR | 25~80 | DIN 933 + BS 4518 |
