Anti-Seize for Stainless Steel Fasteners
Anti-seize compound selection for stainless steel bolts and fittings to prevent galling and thread seizure during assembly and disassembly.
Stainless steel fasteners are prone to galling—cold welding of thread surfaces during tightening. This occurs because the passive oxide layer that gives stainless steel its corrosion resistance also reduces surface lubricity.
Why Copper Anti-Seize Should Be Avoided
Copper-based anti-seize creates a galvanic cell when used with stainless steel, potentially causing:
- Pitting corrosion of the stainless steel
- Copper migration into the grain boundaries
- Accelerated stress corrosion cracking
Recommended Anti-Seize Types for Stainless Steel
| Type | Temperature Range | Best For |
|---|---|---|
| Nickel-based | -50°C to +1315°C | High-temp, chemical processing |
| Nickel/graphite | -50°C to +980°C | General industrial |
| PTFE-based | -50°C to +260°C | Food/pharma, low temp |
| Molybdenum disulfide | -50°C to +450°C | High load, vacuum |
Torque Reduction
Anti-seize reduces friction, which increases clamp load at a given torque. Compensate by:
- Reducing torque to 70-80% of dry torque specification
- Using manufacturer’s K-factor if provided
- Testing actual clamp load for critical applications
Application Procedure
- Clean threads thoroughly—remove corrosion, old compound
- Apply thin, even coating to bolt threads
- Work compound into thread valleys
- Avoid excessive buildup that might contaminate mating surfaces
- Assemble and torque to adjusted specification
Galling Prevention During Assembly
In addition to anti-seize:
- Slow threading speed reduces galling risk
- Use fine threads when possible (more contact area)
- Consider different alloys for bolt and nut (e.g., 316 bolt, 316L nut)
Operating Conditions
| Operating Parameter | Typical Range/Value |
|---|---|
| Temperature Range | -50°C to +1300°C depending on compound type |
| Fastener Materials | 304, 316, 17-4 PH stainless steels common |
| Environment | May include saltwater, chemicals, high temperature |
| Assembly Condition | Both new assembly and disassembly of corroded parts |
| Galling Risk | High—stainless-to-stainless contact prone to galling |
Required Lubricant Properties
| Required Property | Specification |
|---|---|
| Base Type | Nickel-based or copper-free formulation |
| Temperature Rating | Copper-free: to +980°C; Nickel: to +1315°C |
| Corrosion Protection | Must prevent galvanic corrosion |
| Metal Content | Nickel, graphite, or PTFE (not copper for stainless) |
| Torque Factor | Known K-factor for accurate torque values |
| Chemical Resistance | Per application environment |
Compatibility Warnings
- -Copper-based anti-seize may cause galvanic corrosion with stainless steel
- -Some anti-seize compounds are not suitable for oxygen service
- -Torque values must be adjusted when using anti-seize (typically reduce by 20-30%)
Availability
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Sources
- ASTM F1137 - Zinc/Aluminum Corrosion Protective Coatings
- Henkel Loctite Anti-Seize Selection Guide
- Permatex Technical Data Sheets
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