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ASME B18.1.1-1972 (2016) — Small Solid Rivets
🔩 ASME B18.1.1-1972 (2016), Small Solid Rivets, is the foundational dimensional standard for small solid rivets of 7/16 inch nominal diameter and smaller in the American National Standards system. It was developed jointly under the sponsorship of the American Society of Mechanical Engineers (ASME) and the Society of Automotive Engineers (SAE), issued in 1972 and reaffirmed in 2016. The Standard provides complete general and dimensional data for those rivet types recognized as “American National Standard,” together with an appendix of the formulas on which the dimensional data are based. It gives engineers a single reference for selection, drawing callouts, and acceptance inspection. Small solid rivets are the most common permanent fasteners in sheet-metal work, agricultural equipment, vehicles, electrical apparatus, and light metal products, which is why the dimensional system in this Standard is so widely cited.
💡 A rivet is a “permanent” fastener: once the head is upset, it cannot be removed without damaging the parts it joins. Settle the diameter, length, type, and material at the selection stage, and write the acceptance rules into the procurement specification.
1. Scope and Applicability 📌
Section 1 defines the scope precisely: the Standard covers complete general and dimensional data for those types of small solid rivets recognized as “American National Standard.” All other types of small solid rivets within the diameter limits contained in the Standard are to be considered special. An appendix gives the formulas on which the dimensional data are based; however, where questions arise concerning acceptance of product, the dimensions in the tables govern over recalculation by formula. In other words, the tabulated values take precedence over the computed results.
⚠️ Another boundary condition is easily overlooked: inclusion of dimensional data in the Standard is not intended to imply that all described products are stock production sizes. Some sizes may be special-order items, so consumers should consult manufacturers about availability and lead time before purchasing.
Historically, American National Standards Committee B18 (bolts, screws, nuts, rivets, and similar fasteners) was organized in March 1922, and its Subcommittee 1 was charged with rivet standardization. The standard approved in 1927 as B18a-1927 established the basis for solid rivets under 1/2 inch; the proposed standard for tinners, coopers, and belt rivets was granted tentative recognition in 1928 and approved as B18g-1928 in January 1929. These were combined into B18.1-1953, revised again in 1965, and finally designated an American National Standard, ANSI B18.1.1-1972, on January 12, 1972. The document was reaffirmed in 2016.
2. Rivet Types and Head Forms 🔧
The Standard specifies small solid rivets in these types: flat head, flat countersunk head, button head, pan head, truss head, tinners, coopers, belt, and 60-degree flat countersunk head rivets. Each type has its own head profile, head diameter, and height proportions to suit different assembly spaces, load directions, and appearance requirements. Countersunk types, for example, are used where the head must finish flush with the surface, while the large, shallow truss head spreads the bearing load over a wider area on soft materials.
| Rivet Type | Head Characteristic | Typical Application |
|---|---|---|
| Flat Head | Flat head, slightly crowned top | General sheet-metal and structural joints |
| Flat Countersunk | Conical head, flush after upsetting | Surfaces that must stay smooth |
| 60° Countersunk | 60° included angle, shallow embedment | Thin sheet and confined spaces |
| Button Head | Hemispherical head | Connections where appearance matters |
| Pan Head | Cylindrical skirt with rounded top | General mechanical assembly |
| Truss Head | Large diameter, low height | Soft materials, wide bearing area |
| Tinners | Large flat head, short shank | Thin metal sheet joining |
| Coopers | Large-diameter thin head | Wooden barrels, leather goods |
| Belt | Flat, broad head | Belts and fabric joining |
3. Size Series and Designation 📏
Nominal sizes are tabulated by type: Tables 1 through 5 give nominal sizes of rivets in fractions of an inch or decimals for the respective types, while Tables 6 through 9 give the corresponding sizes for certain types. Typical nominal diameters span the common range from 1/16 inch to 7/16 inch, including 1/16, 3/32, 1/8, 5/32, 3/16, 7/32, 1/4, 9/32, 5/16, 11/32, 3/8, and 7/16 inch. The nominal diameter also fixes the shank-length series and head dimensions, so diameter, length, and type must always be specified together; a diameter-only callout is an ambiguous order.
| Nominal Diameter (in.) | Approx. Metric (mm) | Typical Use |
|---|---|---|
| 1/16 | 1.6 | Instruments, very thin sheet |
| 3/32 | 2.4 | Electrical apparatus, light sheet |
| 1/8 | 3.2 | General sheet-metal parts |
| 3/16 | 4.8 | Farm equipment, light structures |
| 1/4 | 6.4 | General structural parts |
| 5/16 | 7.9 | Joints carrying moderate tension |
| 3/8 | 9.5 | Heavy sheet and structures |
| 7/16 | 11.1 | Largest small-rivet size in the Standard |
The Standard also offers guidance on catalog presentation: where other size designations, such as Birmingham wire gage numbers, are shown interposed with “American National Standard” sizes, the data should be presented so that it is clear which diameters are and which are not American National Standard sizes, avoiding confusion in procurement and inspection.
💡 Although the head and shank proportions are derived from formulas in the appendix, acceptance is always based on the tabulated values. When calling out rivets on drawings, quote the standard tabular figures directly rather than converting from the formula.
4. Engineering Practice Essentials 🛠️
- 🔍 Selection workflow: determine head type from sheet thickness, assembly space, and load direction → choose nominal diameter from the hole size → set the shank length (the protrusion needed to form the upset head is typically 1 to 1.5 times the diameter) → confirm the item is a stock or standard size.
- 🔧 Hole fit: the through-hole is normally slightly larger than the rivet shank, giving a clearance fit. An oversized hole lets the shank shift after upsetting, while an undersized hole makes insertion difficult and can damage the shank.
- 📊 Materials and finishes: rivets are commonly made of low-carbon steel, aluminum, and copper; finishes include zinc, nickel, or anodizing. Always check electrochemical compatibility with the joined base metal to avoid galvanic corrosion.
- 📋 Special rivets: any type not listed in the Standard is treated as “special” and requires agreement with the manufacturer on supply, dimensions, and acceptance terms, clearly stated in the technical documents.
- ✅ Acceptance inspection: sample-inspect against the standard tabular dimensions, verifying head form, shank diameter, shank length, and their tolerances for the specific type.
⚠️ Riveting is a non-removable joint; once upset it cannot be dismantled without damage. Where periodic maintenance or part replacement is expected, prefer bolted connections; if riveting is unavoidable, confirm material compatibility and plan the maintenance strategy in advance.
5. Frequently Asked Questions ❓
❓ Q: How does B18.1.1 relate to the old B18.1 number?
A: ANSI B18.1.1-1972 is the current designation for the small solid rivet standard, superseding B18.1-1965. It was approved in 1972 and reaffirmed in 2016, so the current effective edition is B18.1.1-1972 (2016).
A: ANSI B18.1.1-1972 is the current designation for the small solid rivet standard, superseding B18.1-1965. It was approved in 1972 and reaffirmed in 2016, so the current effective edition is B18.1.1-1972 (2016).
❓ Q: When is a rivet considered “special”?
A: Within the 7/16 inch and smaller diameter range, any rivet type not among those listed (flat, flat countersunk, button, pan, truss, tinners, coopers, belt, 60° countersunk) is considered special and requires separately negotiated supply and acceptance terms.
A: Within the 7/16 inch and smaller diameter range, any rivet type not among those listed (flat, flat countersunk, button, pan, truss, tinners, coopers, belt, 60° countersunk) is considered special and requires separately negotiated supply and acceptance terms.
❓ Q: For acceptance, do we use the formula or the tabulated values?
A: Use the tabulated values. The Standard states explicitly that where questions arise concerning acceptance of product, the dimensions in the tables govern over recalculation by formula; state this clearly in acceptance agreements.
A: Use the tabulated values. The Standard states explicitly that where questions arise concerning acceptance of product, the dimensions in the tables govern over recalculation by formula; state this clearly in acceptance agreements.
🔍 Q: What if a catalog lists Birmingham wire gage numbers?
A: When other designations such as Birmingham wire gage numbers appear alongside American National Standard sizes, they must be clearly distinguished so that readers know which diameters are standard and which are not, preventing procurement errors.
A: When other designations such as Birmingham wire gage numbers appear alongside American National Standard sizes, they must be clearly distinguished so that readers know which diameters are standard and which are not, preventing procurement errors.
