A4 Stainless Steel Hex Socket Pipe Plugs are supplied to DIN 906 (taper thread) / DIN 908 (parallel thread with seal). The grade provides superior, including marine and chloride environments and is largely non-magnetic; the practical service range is approx. -200 °C to +400 °C, subject to the property class and the joint. Property data, grade comparison and the full size table follow.
Why Choose A4 Stainless Steel for Hex Socket Pipe Plugs
Specified for marine, coastal and chemical applications. For hex socket pipe plugs, 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 |
Corrosion Behavior in Service
A4 (316) adds 2–3% molybdenum to the A2 (304) composition, which dramatically improves resistance to chloride-pitting corrosion. For Hex Socket Pipe Plugs in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Galvanic & Galling Considerations
Two important notes for stainless hex socket pipe plugs: (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.
Using Stainless Fasteners in Aluminum
The galvanic couple here runs the wrong way: aluminum is the less noble metal, so it corrodes and the fastener does not. What governs the rate is the ratio of areas — a large anode and a small cathode is a tolerable combination, the reverse concentrates the attack into thin material around the hole. An isolating washer plus sealant breaks the circuit; where that is impractical, match the fastener to the substrate.
Sizes of Hex Socket Pipe Plugs Available in A4 Stainless Steel
| Standard | Thread form | Seals on | Needs a washer |
|---|---|---|---|
| DIN 906 | taper (R / NPT) | the thread flanks | no |
| DIN 908 | parallel (G / M) | the face under the head | yes u2014 bonded or USIT ring |
| DIN 910 | parallel (G / M), hex head | the face under the head | yes u2014 bonded or USIT ring |
| DIN 7604 | parallel (G / M), hex head, low profile | the face under the head | yes u2014 bonded or USIT ring |
