Phos + oil≤ 200 °C
Phosphate and oil
A manganese or zinc phosphate conversion layer sealed with oil. It is not really a corrosion coating — it is a running-in surface that holds oil, prevents galling on first assembly, and keeps studs from rusting in the crate.
Specification
| Standards | ASTM F1137 · DIN 50942 · MIL-DTL-16232 · ISO 9717 |
|---|---|
| Thickness | 5 – 15 µm (photphat mangan) |
| Colour | Matt black to dark grey |
| Maximum temperature | 200 °C |
| Salt spray, ASTM B117 | 24 – 72 h — bao ve tam thoi, khong hon |
| Friction | µ ≈ 0,12 – 0,18 khi con dau — tang nhanh khi dau kho |
What it does well
- The standard finish B7 studs are supplied in worldwide — instantly recognisable
- Excellent anti-galling behaviour on first tightening
- Cheapest option, and adds essentially no thickness to the thread
- A sound base layer under paint or PTFE
Where it falls short
- Gives almost no long-term corrosion protection once the oil has dried or washed off
- Unsuitable for any outdoor or marine exposure
- Studs left in an unheated store will surface-rust within months
Specify it when
Insulated or lagged flanges, indoor process piping, and studs that will be coated or painted later.
Grades we apply it to
Need a quotation?
Send us the grade, size and quantity. We reply within one working day with price, lead time and the certificate package included.