Grease Nipples (DIN 71412) manufactured in A4 Stainless Steel (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80) are dimensioned to DIN 71412 / ISO 6392 (lubricating nipples). The sections below give the mechanical and physical properties of the grade, its behavior in corrosive and elevated-temperature service, and the full size table.
Why Choose A4 Stainless Steel for Grease Nipples (DIN 71412)
Specified for marine, coastal and chemical applications. For grease nipples (din 71412), 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 Grease Nipples (DIN 71412) in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Comparable Grades
For Grease Nipples (DIN 71412), the alternative stainless grade is A2 (304). The practical dividing line is chlorides: A2 (304) is fine until salt is involved, and A4 (316) exists for the cases where it is — coastal, marine and road-salt service. Neither reaches the strength of a plated class 8.8 or 10.9 fastener.
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 Grease Nipples (DIN 71412) Available in A4 Stainless Steel
| Thread | Head angle | Form | Notes |
|---|---|---|---|
| M6 x 1.0 | straight (form A) | DIN 71412 A | commonest small nipple |
| M8 x 1.0 | straight (form A) | DIN 71412 A | general machinery |
| M8 x 1.25 | straight (form A) | DIN 71412 A | general machinery |
| M10 x 1.0 | straight (form A) | DIN 71412 A | general machinery |
| M10 x 1.0 | 45 degrees (form B) | DIN 71412 B | where a straight gun will not reach |
| M10 x 1.0 | 90 degrees (form C) | DIN 71412 C | tight or shrouded positions |
| R 1/8 in | straight (form A) | DIN 71412 A | tapered pipe thread |
| R 1/4 in | straight (form A) | DIN 71412 A | tapered pipe thread |
| 1/4-28 UNF | straight | inch series | imported and automotive equipment |
