Grade 8.8 Steel Hydraulic Compression Fittings are stocked to DIN 2353. The grade provides requires plating (zinc) for corrosion protection and is magnetic; the practical service range is up to approx. +300 °C. Property data, grade comparison and the full size table follow.
Why Choose Grade 8.8 Steel for Hydraulic Compression Fittings
The workhorse medium-carbon alloy grade for structural joints. For hydraulic compression fittings, this matters when requires plating (zinc) for corrosion protection is the primary requirement.
Mechanical & Physical Properties
| Grade designation | class 8.8 |
|---|---|
| Magnetic response | Magnetic |
| Service temperature | up to approx. +300 °C |
| Corrosion characteristic | Requires plating (zinc) for corrosion protection |
Corrosion Behavior in Service
Carbon and alloy steel hydraulic compression fittings 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 hydraulic compression fittings 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 Hydraulic Compression Fittings Available in Grade 8.8 Steel
| Tube OD (mm) | Nut length L (mm) | Nut width across flats (mm) | Tube bore (mm) | Max working pressure (bar) | Mating thread | Reference standard | Notes |
|---|---|---|---|---|---|---|---|
| 4 | 22 | 13 | 8 | 400 | M10x1 | DIN 2353 / ISO 8434-1 | Compression hydraulic fitting |
| 5 | 24 | 14 | 9 | 400 | M12x1.5 | DIN 2353 / ISO 8434-1 | Compression hydraulic fitting |
| 6 | 27 | 17 | 11 | 400 | M14x1.5 | DIN 2353 / ISO 8434-1 | Compression hydraulic fitting |
| 8 | 30 | 19 | 13 | 400 | M16x1.5 | DIN 2353 / ISO 8434-1 | Compression hydraulic fitting |
| 10 | 33 | 22 | 16 | 400 | M18x1.5 | DIN 2353 / ISO 8434-1 | Compression hydraulic fitting |
| 12 | 36 | 24 | 18 | 315 | M22x1.5 | DIN 2353 / ISO 8434-1 | Compression hydraulic fitting |
| 14 | 39 | 27 | 20 | 315 | M26x1.5 | DIN 2353 / ISO 8434-1 | Compression hydraulic fitting |
| 15 | 39 | 27 | 20 | 315 | M26x1.5 | DIN 2353 / ISO 8434-1 | Compression hydraulic fitting |
| 16 | 42 | 30 | 22 | 315 | M26x1.5 | DIN 2353 / ISO 8434-1 | Compression hydraulic fitting |
| 18 | 45 | 32 | 25 | 250 | M30x2 | DIN 2353 / ISO 8434-1 | Compression hydraulic fitting |
| 20 | 48 | 36 | 27 | 250 | M30x2 | DIN 2353 / ISO 8434-1 | Compression hydraulic fitting |
| 22 | 51 | 38 | 30 | 250 | M36x2 | DIN 2353 / ISO 8434-1 | Compression hydraulic fitting |
| 25 | 55 | 41 | 32 | 250 | M36x2 | DIN 2353 / ISO 8434-1 | Compression hydraulic fitting |
| 28 | 58 | 46 | 36 | 160 | M42x2 | DIN 2353 / ISO 8434-1 | Compression hydraulic fitting |
| 30 | 60 | 48 | 38 | 160 | M42x2 | DIN 2353 / ISO 8434-1 | Compression hydraulic fitting |
| 35 | 66 | 55 | 44 | 160 | M52x2 | DIN 2353 / ISO 8434-1 | Compression hydraulic fitting |
| 38 | 69 | 58 | 47 | 160 | M52x2 | DIN 2353 / ISO 8434-1 | Compression hydraulic fitting |
| 42 | 74 | 65 | 52 | 100 | M60x2 | DIN 2353 / ISO 8434-1 | Compression hydraulic fitting |