Cadmium plating
Electrolytic cadmium plating to ASTM B766 class 12 type II, with 1,000 hours of salt spray in an ASTM B117 report from an ISO/IEC 17025 accredited test.
A uniform layer with natural lubricating properties, high resistance to galvanic corrosion and good performance in threaded joints — the historical reference coating for critical fasteners in marine environments and severe atmospheres. Cadmium faces growing environmental restriction in several jurisdictions, which makes replacement by zinc-nickel or NanoGalv® a natural technical conversation: Sapucaia is one of the few that offers all three and can lead the migration.
High-strength sacrificial protection, galvanic compatibility with aluminum and torque-tension behavior on threads. Restricted in the EU since 1991 — with the exemption kept for offshore, nuclear and aerospace.
Two properties explain why cadmium is still specified after so much restriction. The first is torque-tension behavior: the layer has natural lubricity, so the threaded joint tightens with a low, predictable friction coefficient, and that predictability is what the designer uses to calculate preload. The second is galvanic compatibility with aluminum — in a light-alloy assembly, replacing cadmium with another coating can move corrosion to the structure instead of eliminating it.
The typical application is critical fasteners in marine environments and severe atmospheres: aircraft parts, subsea fasteners on platforms, wellhead equipment components. Those are exactly the three niches where the European restriction has kept an exemption since 1991 — offshore, nuclear and aerospace.
Sapucaia applies cadmium, zinc-nickel and NanoGalv®. That changes the nature of the replacement conversation: when the project standard allows a swap, we lead the migration with the test alongside, and we have no commercial interest in the answer being one or the other.
Note: LHE aerospace cadmium meets AMS-QQ-P-416 — a requirement of 96 h with no white corrosion. It is an aerospace-sector standard, not oil & gas: in O&G the designation is ASTM B766 class 12 type II. Confirmed on the EBRATS 2026 showcase cards.
Technical data
- Thickness (O&G practice)
- 12 µm
- Salt spray
- 1,000 h · ASTM B117
- Report
- ISO/IEC 17025 accredited test
- Standard
- ASTM B766 · class 12, type II
- Finishes
- Yellow chromate · olive drab
- Approval
- TechnipFMC
What each standard sets for Cadmium.
The chip at the top of the page names the standard. This table says what it requires — which is what the specifier checks before closing the drawing.
| Standard | What it covers | What it sets here |
|---|---|---|
| ASTM B766 | Coating specification | The standard for electrodeposited cadmium. Class 12 and type II is the oil and gas designation, and it applies to both the yellow and the olive drab finish. |
| AMS-QQ-P-416 | Aerospace specification | The standard of the AEROSPACE sector — not of oil and gas. It governs low-hydrogen-embrittlement cadmium (LHE) on aircraft parts. |
| ASTM B849 | Stress relief, before the bath | Heat treatment prior to coating. The standard and the class come from the customer’s specification — it is the step Petrobras cites together with B850. |
| ASTM B850 | Hydrogen relief | Post-coating treatment to reduce the risk of hydrogen embrittlement in high-strength steel. |
| ASTM B117 | Test method | Neutral salt spray. It is the method of the 1,000 h report — and it is a test method, not a coating specification: it does not replace B766. |
| Petrobras N-215 | Operator specification | Coating requirements for components in oil and gas service. |
The applications that come here.
Subsea fasteners
Studs, nuts and bolts of subsea equipment, where the project standard still specifies cadmium and inspection costs more than the part.
Aircraft parts
Structural and system components in light alloy, for galvanic compatibility with aluminum — in the low-embrittlement variant, under AMS-QQ-P-416.
Calculated threaded joint
Where the design depends on a predictable friction coefficient to reach preload: the natural lubricity of the layer is what makes torque repeatable.
Led migration
When the standard allows replacement, the same supplier applies zinc-nickel and NanoGalv® — so the comparison comes with a test, not a sales argument.
Variations of this line.
Cadmium yellow chromate
The historical reference coating for critical fasteners in marine environments: 1,000 hours to red rust, in accredited testing.
Cadmium olive drab chromate
The same protection as yellow chromate, in the olive drab finish required by military and aerospace specifications.
Cadmium LHE for aerospace
LHE stands for low hydrogen embrittlement. On a structural aerospace component, hydrogen embrittlement gives no second chance.
What specifiers usually ask.
Can cadmium still be used?
Yes, in the sectors where the standard requires or allows it. The European Union restriction dates from 1991 and kept an exemption for offshore, nuclear and aerospace — precisely the applications where substitution is not trivial. Cadmium is regulated, not superseded.
Why is replacing cadmium with zinc-nickel not automatic?
Because cadmium delivers two things the substitute has to reproduce: predictable torque-tension in a threaded joint and galvanic compatibility with aluminum. In a light-alloy assembly, a badly sized swap moves corrosion to the structure. Migration is done with the project standard in hand and a comparative test, not by analogy.
What is the correct cadmium designation in oil and gas?
ASTM B766 class 12 type II, and it applies to both the yellow chromate and the olive drab. The practical thickness in oil and gas is 12 µm. In aerospace the designation is different: AMS-QQ-P-416.
What proof comes with cadmium?
An ASTM B117 salt-spray report with 1,000 hours to red rust, in an ISO/IEC 17025 accredited test. The method is written next to the number because it is the first thing the specifier checks — hours without a method specify nothing.