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Fastener Standardization for Washers and Lockwashers: SAE J2655-2015 Explained
Selecting the correct washer or lockwasher for ship systems and equipment just became more straightforward with SAE J2655-2015. This standard centralizes inch-dimensioned washers and lockwashers—including flat, helical, toothed, and tab types—into a single part identification number (PIN) system. It aligns with ASME B18.21.1 and introduces modern coating options while prohibiting hazardous hexavalent chromium. Engineers can now order components with fewer errors and greater confidence, whether for military, marine, or general industrial use.
The Part Identification Number (PIN) System
The PIN is the backbone of SAE J2655-2015. It encodes the washer configuration, nominal diameter, special features, material, and finish in a structured format. The PIN consists of five fields (four for some types) with no blank spaces, making it easy to communicate precise requirements. For example, a flat washer in carbon steel with zinc coating might be identified as J2655-8-3-G1-ZA, where Field 1 is the standard base, Field 2 the configuration, Field 3 the diameter, Field 4 the material (G1 for carbon steel), and Field 5 the coating (ZA for zinc electroplate with clear topcoat).
This approach eliminates ambiguity in procurement and manufacturing, as every PIN directly corresponds to defined dimensions, materials, and finishes. The standard even includes appendices for non-standard flat washers and Navy-typical lock plates, expanding its utility.
🛠️ Insight: The PIN system reduces ordering errors by up to 60% in some applications, as it removes the need for lengthy text descriptions and manual cross-referencing between separate standards.
Material and Coating Designators
Tables 6 and 7 of SAE J2655-2015 list material designators (Field 4) and permitted finishes (Field 5) for each washer type. Materials include carbon steel, alloy steel, stainless steel, brass, copper alloys, phosphor bronze, and nickel alloys. Hardness requirements are specified to ensure performance. Coatings range from electrodeposited zinc (designators Z, ZA, ZC) to zinc flake (designator F) and hot-dip galvanizing. The latest revision replaces outdated references with ISO 10683 for zinc flake coatings and removes hexavalent chromium from all permitted finishes.
| Designator | Material | UNS Alloy | Typical Hardness |
|---|---|---|---|
| G1 | Carbon Steel | ― | 38–45 HRC |
| S1 | Stainless Steel (304) | S30400 | B85–100 HRB |
| S2 | Stainless Steel (316) | S31600 | B85–100 HRB |
| C2 | Brass | C26000 | B75–95 HRB |
| N7 | Nickel-Copper Alloy | N05500 | B80–95 HRB |
Coating designators have also been updated. Designator F (zinc flake per ISO 10683) is now a permitted alternative to electrodeposited coatings, offering superior corrosion resistance in harsh environments. Designators ZA and ZC replace previous unclear designations, providing clear specification for topcoat types. Designator Z remains as a catch-all that allows either ZA or ZC to be supplied.
Addressing Hazardous Materials and Modern Coatings
The 2015 revision introduces a firm prohibition on hexavalent chromium in all coatings, aligning with global environmental regulations. This replaces earlier allowances and forces manufacturers to use safer alternatives such as trivalent chromium passivates or zinc flake. The standard also clarifies salt spray corrosion protection requirements for electrodeposited coatings, ensuring consistent performance in marine environments.
Additionally, the standard now includes guidance for specifying CRES 316 (molybdenum-bearing stainless steel) and adds Appendix B for lock plates and tab lock washers common in Navy designs. This makes J2655 more comprehensive for defense and commercial shipbuilding.
⚠️ Important: When specifying coatings, always verify that the chosen designator does not contain hexavalent chromium. Designators that were previously allowed (such as Designator A for aluminum and Designator C) have been inactivated or removed in J2655-2015 to comply with environmental standards.
Frequently Asked Questions
- How do I construct a PIN for a flat washer?
Follow Figure 1 in the standard: start with the document number (J2655), then the configuration code (e.g., 0 for round flat washer), the nominal diameter (based on ASME B18.21.1), the material designator from Table 6, and optionally a coating designator from Table 6. Example: J2655-0-8-G1-ZA for a 1/2-inch carbon steel flat washer with clear zinc coating. - What are the permitted materials for lockwashers?
Helical spring lock washers are typically carbon steel or stainless steel; toothed lock washers add phosphor bronze and nickel alloys. Refer to Table 7 in the standard for a complete list of designators and hardness limits. - Why are hexavalent chromium coatings prohibited?
Hexavalent chromium is a known carcinogen and restricted under many environmental regulations. The 2015 revision aligns J2655 with modern occupational health and disposal requirements, ensuring safer handling and reduced environmental impact. - How do I select the correct coating designator?
Consider the environmental exposure: for moderate corrosion resistance, electrodeposited zinc (ZA, ZC) is common; for high salt-spray resistance, choose zinc flake (F). If the application is in ship systems, consult the coating guidance in SAE J2280. Always confirm with your supplier the exact coating type and thickness.
SAE J2655-2015 represents a major step forward in washer and lockwasher standardization. By adopting the PIN system and referencing the latest ASME dimensions, engineers can ensure consistency, reduce mistakes, and meet modern material and environmental requirements—all while simplifying the supply chain.
