Why Material Selection Matters
In food and pharma environments, fastener corrosion isn't just an aesthetic issue — corroded fasteners create:
Recall risk
Contaminated product can require expensive recalls
Inspection failures
FDA, USDA, or EU audits
Particle contamination
Rust or coating flakes can contaminate product
Pitting that harbors bacteria
Difficult or impossible to clean
Recommended Materials by Application
Stainless Steel — General Food Service
Suitable for most indoor food service applications away from harsh chemical exposure:
- Mild detergent cleaning — Dish washers, sink areas
- Dry food processing — Bakeries, dry mixers
- Refrigeration equipment — Walk-in coolers, freezers
- Stainless steel cabinetry — Prep tables, cabinets
Stainless Steel — Premium Food/Pharma
Required for chloride-heavy environments and direct food contact:
- Meat and seafood processing — Salt exposure, brining solutions
- Beverage processing — Acidic environments (citrus, tomato)
- Pharmaceutical clean rooms — Where cleaning chemicals are aggressive
- Dairy processing — High temperatures + cleaning chemicals
- Marine food (commercial fishing) — Saltwater splash
Avoid in Food Service
Standard carbon steel (any plating)
Will rust eventually
Cadmium-plated
Health concerns, not FDA-compliant
Brass
Lead concerns, especially in older brass alloys
Plain zinc plating
Will corrode in cleaning environments
Sanitary Design Principles
Beyond material selection, fastener choice affects cleanability:
Hex Head vs Socket Head
- Hex Head: Easier to grip with cleaning equipment, no socket to harbor food/bacteria
- Socket Head: The hex socket can collect food debris — use only where cleanability isn't critical
Smooth Surfaces vs Threads
- Tapered/Conical surfaces — Easier to clean
- Sharp corners — Bacterial harborage
- Exposed threads — Avoid where possible; use shoulder bolts or unthreaded sections in direct food contact areas
Self-Draining Design
Avoid fastener configurations that create dead spaces where liquid can pool:
- Use sloped surfaces
- Open-bottom designs vs closed
- Vented assemblies where required
Sample Construction Fastener Specifications
| Application | Material | Finish | |
|---|---|---|---|
| Sink/dishwasher mounting | 304 stainless | Passivated | |
| Refrigeration unit | 304 stainless | Passivated | |
| Conveyor belt structure (dry food) | 304 stainless | Electropolished | |
| Meat processing equipment | 316 stainless | Electropolished | |
| Pharmaceutical clean room | 316L stainless | Electropolished | |
| Dairy processing | 316 stainless | Polished | |
| Beverage bottling | 316 stainless | Polished | |
| Bakery equipmen | 304 stainless | Passivated |
Common Mistakes in Food Service
Reusing fasteners after corrosion
Replace any fastener showing surface corrosion. Don't trust visual appearance alone
Mixing stainless grades
A 304 fastener in a 316 environment will be the weakest link.
Wrong cleaning protocol
Chloride bleach can pit stainless. Use approved sanitizers per equipment manufacturer.
Not isolating dissimilar metals
Steel fasteners in stainless equipment cause galvanic corrosion.
Galling on stainless
Stainless threads can cold-weld during tightening. Use anti-seize compound (food-grade where required) and proper torque.
Regulatory Considerations
FDA (United States)
21 CFR 175 — Materials in contact with food. 304 and 316 stainless are well-established as compliant for incidental food contact.
3-A Sanitary Standards — Dairy industry equipment standards. Stainless construction with proper passivation typically meets requirements.
USDA
Meat and poultry processing requires USDA-acceptable materials. Stainless steel with proper finishes typically qualifies.
EU / European
EC 1935/2004 — Materials in contact with food. Stainless steel typically compliant.
Medical Device
For implantable medical devices, stricter material certifications apply (ASTM F138 for 316L, ASTM F899 for various alloys). Contact our specialty sales for medical device fasteners.
Get Help with Food Service Selection
For specific applications, contact our food service specialist:
- Sanitary design verification
- Specific FDA/USDA compliance questions
- Material certifications and traceability
- Custom electropolished items
- Volume pricing for large equipment manufacturers