A4 Stainless Steel (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80) is specified for marine, coastal and chemical applications. When push-in pneumatic fittings are specified in this grade, the dimensions remain per Industry standard; the material determines corrosion behavior (superior, including marine and chloride environments) and the service temperature range (approx. -200 °C to +400 °C, subject to the property class and the joint). Both are covered below with the size table.
Why Choose A4 Stainless Steel for Push-In Pneumatic Fittings
Specified for marine, coastal and chemical applications. For push-in pneumatic fittings, this matters when superior, including marine and chloride environments is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80 |
|---|---|
| Magnetic response | Largely non-magnetic |
| Service temperature | approx. -200 °C to +400 °C, subject to the property class and the joint |
| Corrosion characteristic | Superior, including marine and chloride environments |
Galvanic & Galling Considerations
Two important notes for stainless push-in pneumatic fittings: (1) stainless can gall on stainless threads under load — use a thread lubricant or anti-galling compound, especially for M6 and below; (2) when joined to aluminum or galvanized steel, stainless can drive galvanic corrosion of the less-noble metal in wet service — isolate with a coating or sleeve where appropriate.
Comparable Grades
For Push-In Pneumatic Fittings, the alternative stainless grade is A2 (304). A2 (304) suits general indoor and outdoor service; A4 (316) adds molybdenum for marine and chloride environments. Where higher strength matters more than corrosion, switch to plated alloy-steel class 8.8 or 10.9.
Using Stainless Fasteners in Aluminum
Stainless steel is more noble than aluminum, so in the presence of an electrolyte — rain, condensation, salt spray — the aluminum becomes the anode and corrodes at the joint. The effect is driven by the area ratio: a small stainless fastener in a large aluminum section is normally acceptable, while a large stainless fastener in thin aluminum is not. Where the joint is wet, isolate the two metals with a coated or nylon washer and a sealant, or specify an aluminum or coated fastener instead.
Sizes of Push-In Pneumatic Fittings Available in A4 Stainless Steel
| Tube OD (mm) | Thread size | Flow ref (Nl/min) | Max pressure (bar) | Pull-out force (N) | Reference standard | Notes |
|---|---|---|---|---|---|---|
| 4 | M5x0.8 | 80 | 10 | 70 | ISO 6150 | Push-in pneumatic fitting for PA/PU tubing |
| 4 | 1/8 BSP | 80 | 10 | 70 | ISO 6150 | Push-in pneumatic fitting for PA/PU tubing |
| 6 | M5x0.8 | 200 | 10 | 120 | ISO 6150 | Push-in pneumatic fitting for PA/PU tubing |
| 6 | 1/8 BSP | 200 | 10 | 120 | ISO 6150 | Push-in pneumatic fitting for PA/PU tubing |
| 6 | 1/4 BSP | 200 | 10 | 120 | ISO 6150 | Push-in pneumatic fitting for PA/PU tubing |
| 8 | 1/4 BSP | 350 | 10 | 180 | ISO 6150 | Push-in pneumatic fitting for PA/PU tubing |
| 8 | 3/8 BSP | 350 | 10 | 180 | ISO 6150 | Push-in pneumatic fitting for PA/PU tubing |
| 10 | 1/4 BSP | 500 | 10 | 250 | ISO 6150 | Push-in pneumatic fitting for PA/PU tubing |
| 10 | 3/8 BSP | 500 | 10 | 250 | ISO 6150 | Push-in pneumatic fitting for PA/PU tubing |
| 10 | 1/2 BSP | 500 | 10 | 250 | ISO 6150 | Push-in pneumatic fitting for PA/PU tubing |
| 12 | 3/8 BSP | 700 | 10 | 350 | ISO 6150 | Push-in pneumatic fitting for PA/PU tubing |
| 12 | 1/2 BSP | 700 | 10 | 350 | ISO 6150 | Push-in pneumatic fitting for PA/PU tubing |
| 16 | 1/2 BSP | 1200 | 10 | 500 | ISO 6150 | Push-in pneumatic fitting for PA/PU tubing |
| 16 | 3/4 BSP | 1200 | 10 | 500 | ISO 6150 | Push-in pneumatic fitting for PA/PU tubing |
