ASME B18.15 Forged Eye Bolts (Inch Series, Plain and Shoulder Patterns)
ASME B18.15 forged eye bolts, inch series 1/4 – 2 1/2 in — plain pattern for straight tensile loading and shoulder pattern for limited angular loading, with the collected per-size tables: shank length, eye dimensions, overall length, minimum full thread, shoulder geometry and UNC-2A thread sizes.
Last updated: 2026-11
Specifications
The ASME B18.15 inch-series forged eye bolt is the lifting and tie-down anchor point of the American fastener system: a forged ring (the eye) on a threaded shank, made in two patterns that answer two different loading rules. The plain pattern is for straight tensile pull only — the collected table runs 1/4 through 2 1/2 in with two rows per nominal size (regular and the next-larger section), and its geometry carries no shoulder, so any bending or angular load multiplies stress at the shank-to-eye transition and must be avoided. The shoulder pattern adds a machined shoulder (columns H, J, K and the radius under it in the collected table, 1/4 through 2 in): seated flush against the mating surface, the shoulder resists bending and permits limited angular loading — which is why it is the default choice wherever the sling or tie-down cannot be guaranteed to pull perfectly axial. Both tables print the same per-size core: major thread diameter A, shank length B for styles A and B, eye inside diameter C, eye outside diameter D, eye section diameter E, overall length F, minimum full thread G and the UNC-2A thread size. Preferred nominal sizes are marked bold in the source — see the table footnote. Working load limits, material and finish are not tabulated by the collected specification — per RFQ.
| Standard | ASME B18.15 — forged eyebolts, inch series (plain pattern: straight tensile load only; shoulder pattern: limited angular loading when the shoulder is properly seated) |
|---|---|
| Size range | Nominal 1/4 – 2 1/2 in (plain pattern table) and 1/4 – 2 in (shoulder pattern table); two geometry rows per nominal size in both tables; threads UNC-2A as printed (e.g. 1/4 - 20 … 2 1/2 - 4) |
| Tabulated geometry — plain pattern | Per size: major thread dia. A, shank length B (Style A / Style B), eye I.D. C, nominal eye O.D. D, eye section dia. E, overall length F, min full thread G (Style A / Style B), thread size UNC-2A |
| Tabulated geometry — shoulder pattern | Plain-pattern columns plus: eye-to-shoulder H, shoulder dia. J, shoulder height K, radius under shoulder R (0.015 – 0.095 as printed) |
| Working load / material / finish | Not tabulated by the collected specification — per RFQ (state loading direction, capacity requirement and finish at quotation; use only within the limits of the applicable standard and manufacturer recommendations) |
| Nominal Size (Fraction) | Nominal Size (Decimal) | A — Major Thread Dia. | B — Shank Length Style A | B — Shank Length Style B | C — Eye I.D. | D — Nominal Eye O.D. | E — Eye Sect. Dia. | F — Overall Length | G — Min Full Thread Style A | G — Min Full Thread Style B | Thread Size (UNC-2A) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/4 | 0.25 | 0.25 | 1.00 | 1.00 | 0.69 | 1.19 | 0.19 | 2.06 | 0.75 | 0.75 | 1/4 - 20 |
| 1/4 | 0.25 | 0.28 | 1.06 | 1.06 | 0.81 | 1.19 | 0.25 | 2.38 | 0.75 | 0.75 | 1/4 - 20 |
| 5/16 | 0.31 | 0.31 | 1.12 | 1.06 | 0.81 | 1.44 | 0.25 | 2.44 | 0.81 | 0.75 | 5/16 - 18 |
| 5/16 | 0.31 | 0.34 | 1.19 | 1.13 | 0.94 | 1.44 | 0.31 | 2.75 | 0.81 | 0.75 | 5/16 - 18 |
| 3/8 | 0.38 | 0.38 | 1.25 | 1.12 | 0.94 | 1.69 | 0.31 | 2.81 | 0.88 | 0.75 | 3/8 - 16 |
| 3/8 | 0.38 | 0.41 | 1.38 | 1.25 | 1.06 | 1.69 | 0.38 | 3.19 | 0.88 | 0.75 | 3/8 - 16 |
| 7/16 | 0.44 | 0.44 | 1.38 | 1.13 | 1.00 | 1.81 | 0.34 | 3.06 | 1.00 | 0.75 | 7/16 - 14 |
| 7/16 | 0.44 | 0.47 | 1.50 | 1.25 | 1.12 | 1.81 | 0.41 | 3.44 | 1.00 | 0.75 | 7/16 - 14 |
| 1/2 | 0.50 | 0.50 | 1.50 | 1.13 | 1.12 | 2.12 | 0.44 | 3.50 | 1.12 | 0.75 | 1/2 - 13 |
| 1/2 | 0.50 | 0.53 | 1.62 | 1.25 | 1.25 | 2.12 | 0.50 | 3.88 | 1.12 | 0.75 | 1/2 - 13 |
| 9/16 | 0.56 | 0.56 | 1.62 | 1.21 | 1.19 | 2.25 | 0.47 | 3.75 | 1.25 | 0.84 | 9/16 - 12 |
| 9/16 | 0.56 | 0.59 | 1.75 | 1.34 | 1.31 | 2.25 | 0.53 | 4.12 | 1.25 | 0.84 | 9/16 - 12 |
| 5/8 | 0.62 | 0.62 | 1.75 | 1.31 | 1.31 | 2.56 | 0.56 | 4.19 | 1.38 | 0.94 | 5/8 - 11 |
| 5/8 | 0.62 | 0.66 | 1.88 | 1.44 | 1.44 | 2.56 | 0.62 | 4.56 | 1.38 | 0.94 | 5/8 - 11 |
| 3/4 | 0.75 | 0.75 | 2.00 | 1.50 | 1.44 | 2.81 | 0.62 | 4.69 | 1.62 | 1.13 | 3/4 - 10 |
| 3/4 | 0.75 | 0.78 | 2.12 | 1.62 | 1.56 | 2.81 | 0.69 | 5.06 | 1.62 | 1.13 | 3/4 - 10 |
| 7/8 | 0.88 | 0.88 | 2.25 | 1.75 | 1.56 | 3.19 | 0.75 | 5.31 | 1.81 | 1.31 | 7/8 - 9 |
| 7/8 | 0.88 | 0.91 | 2.38 | 1.88 | 1.69 | 3.19 | 0.81 | 5.69 | 1.81 | 1.31 | 7/8 - 9 |
| 1 | 1.00 | 1.00 | 2.50 | 1.94 | 1.69 | 3.56 | 0.88 | 6.44 | 2.06 | 1.50 | 1 - 8 |
| 1 | 1.00 | 1.06 | 2.62 | 2.06 | 1.81 | 3.56 | 0.94 | 6.88 | 2.06 | 1.50 | 1 - 8 |
| 1 1/8 | 1.12 | 1.12 | 2.75 | 2.23 | 1.94 | 4.06 | 1.00 | 7.31 | 2.31 | 1.69 | 1 1/8 - 7 |
| 1 1/8 | 1.12 | 1.19 | 2.88 | 2.26 | 2.06 | 4.06 | 1.06 | 7.69 | 2.31 | 1.69 | 1 1/8 - 7 |
| 1 1/4 | 1.25 | 1.25 | 3.00 | 2.38 | 2.12 | 4.44 | 1.12 | 8.06 | 2.50 | 1.88 | 1 1/4 - 7 |
| 1 1/4 | 1.25 | 1.34 | 3.12 | 2.50 | 2.25 | 4.44 | 1.19 | 8.44 | 2.50 | 1.88 | 1 1/4 - 7 |
| 1 1/2 | 1.50 | 1.50 | 3.50 | 2.75 | 2.44 | 5.19 | 1.31 | 9.22 | 3.00 | 2.25 | 1 1/2 - 6 |
| 1 1/2 | 1.50 | 1.59 | 3.62 | 2.87 | 2.56 | 5.19 | 1.38 | 9.56 | 3.00 | 2.25 | 1 1/2 - 6 |
| 1 3/4 | 1.75 | 1.75 | 3.75 | 3.18 | 2.75 | 6.00 | 1.50 | 10.47 | 3.19 | 2.62 | 1 3/4 - 5 |
| 1 3/4 | 1.75 | 1.84 | 3.88 | 3.31 | 3.00 | 6.00 | 1.56 | 10.88 | 3.19 | 2.62 | 1 3/4 - 5 |
| 2 | 2.00 | 2.00 | 4.00 | 3.62 | 3.06 | 6.88 | 1.75 | 11.62 | 3.38 | 3.00 | 2 - 4 1/2 |
| 2 | 2.00 | 2.09 | 4.12 | 3.79 | 3.44 | 6.88 | 1.88 | 12.12 | 3.38 | 3.00 | 2 - 4 1/2 |
| 2 1/2 | 2.50 | 2.50 | 5.00 | 4.50 | 3.81 | 8.50 | 2.19 | 13.19 | 4.25 | 3.75 | 2 1/2 - 4 |
| 2 1/2 | 2.50 | 2.62 | 5.25 | 4.75 | 4.19 | 8.50 | 2.31 | 14.06 | 4.25 | 3.75 | 2 1/2 - 4 |
- Row 1 (1/4): The source marks preferred nominal sizes in bold within the table; bold formatting does not survive text conversion, so preferred status is not visible here.
| Nominal Size (Fraction) | Nominal Size (Decimal) | A — Major Thread Dia. | B — Shank Length Style A | B — Shank Length Style B | C — Eye I.D. | D — Eye O.D. | E — Eye Sect. Dia. | F — Overall Length | G — Min Full Thread Style A | G — Min Full Thread Style B | Thread Size (UNC-2A) | H — Eye to Shoulder | J — Shoulder Dia. | K — Shoulder Height | R — Radius under Shoulder |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/4 | 0.25 | 0.25 | 1.00 | 1.00 | 0.69 | 1.19 | 0.19 | 2.22 | 0.75 | 0.75 | 1/4 - 20 | 0.69 | 0.50 | 0.12 | 0.015 |
| 1/4 | 0.25 | 0.28 | 1.06 | 1.06 | 0.81 | 1.19 | 0.25 | 2.53 | 0.75 | 0.75 | 1/4 - 20 | 0.81 | 0.56 | 0.19 | 0.025 |
| 5/16 | 0.31 | 0.31 | 1.12 | 1.06 | 0.81 | 1.44 | 0.25 | 2.66 | 0.81 | 0.75 | 5/16 - 18 | 0.88 | 0.56 | 0.12 | 0.015 |
| 5/16 | 0.31 | 0.34 | 1.19 | 1.13 | 0.94 | 1.44 | 0.31 | 2.97 | 0.81 | 0.75 | 5/16 - 18 | 1.00 | 0.62 | 0.19 | 0.025 |
| 3/8 | 0.38 | 0.38 | 1.25 | 1.12 | 0.94 | 1.69 | 0.31 | 3.09 | 0.88 | 0.75 | 3/8 - 16 | 1.06 | 0.62 | 0.12 | 0.015 |
| 3/8 | 0.38 | 0.41 | 1.38 | 1.25 | 1.06 | 1.69 | 0.38 | 3.47 | 0.88 | 0.75 | 3/8 - 16 | 1.19 | 0.69 | 0.19 | 0.025 |
| 7/16 | 0.44 | 0.44 | 1.38 | 1.13 | 1.00 | 1.81 | 0.34 | 3.22 | 1.00 | 0.75 | 7/16 - 14 | 1.19 | 0.75 | 0.19 | 0.015 |
| 7/16 | 0.44 | 0.47 | 1.50 | 1.25 | 1.12 | 1.81 | 0.41 | 3.59 | 1.00 | 0.75 | 7/16 - 14 | 1.31 | 0.81 | 0.25 | 0.025 |
| 1/2 | 0.50 | 0.50 | 1.50 | 1.13 | 1.12 | 2.12 | 0.44 | 3.66 | 1.12 | 0.75 | 1/2 - 13 | 1.31 | 0.88 | 0.19 | 0.015 |
| 1/2 | 0.50 | 0.53 | 1.62 | 1.25 | 1.25 | 2.12 | 0.50 | 4.03 | 1.12 | 0.75 | 1/2 - 13 | 1.44 | 0.94 | 0.25 | 0.025 |
| 9/16 | 0.56 | 0.56 | 1.62 | 1.21 | 1.19 | 2.25 | 0.47 | 3.91 | 1.25 | 0.84 | 9/16 - 12 | 1.50 | 0.94 | 0.22 | 0.020 |
| 9/16 | 0.56 | 0.59 | 1.75 | 1.34 | 1.31 | 2.25 | 0.53 | 4.28 | 1.25 | 0.84 | 9/16 - 12 | 1.62 | 1.00 | 0.28 | 0.045 |
| 5/8 | 0.62 | 0.62 | 1.75 | 1.31 | 1.31 | 2.56 | 0.56 | 4.44 | 1.38 | 0.94 | 5/8 - 11 | 1.59 | 1.00 | 0.25 | 0.025 |
| 5/8 | 0.62 | 0.66 | 1.88 | 1.44 | 1.44 | 2.56 | 0.62 | 4.78 | 1.38 | 0.94 | 5/8 - 11 | 1.72 | 1.06 | 0.31 | 0.045 |
| 3/4 | 0.75 | 0.75 | 2.00 | 1.50 | 1.44 | 2.81 | 0.62 | 4.97 | 1.62 | 1.12 | 3/4 - 10 | 1.72 | 1.12 | 0.25 | 0.020 |
| 3/4 | 0.75 | 0.78 | 2.12 | 1.62 | 1.56 | 2.81 | 0.69 | 5.34 | 1.62 | 1.12 | 3/4 - 10 | 1.91 | 1.25 | 0.31 | 0.045 |
| 7/8 | 0.88 | 0.88 | 2.25 | 1.75 | 1.56 | 3.19 | 0.75 | 5.56 | 1.81 | 1.31 | 7/8 - 9 | 2.03 | 1.31 | 0.31 | 0.040 |
| 7/8 | 0.88 | 0.91 | 2.38 | 1.88 | 1.69 | 3.19 | 0.81 | 5.97 | 1.81 | 1.31 | 7/8 - 9 | 2.22 | 1.44 | 0.38 | 0.065 |
| 1 | 1.00 | 1.00 | 2.50 | 1.94 | 1.69 | 3.56 | 0.88 | 6.44 | 2.06 | 1.50 | 1 - 8 | 2.22 | 1.50 | 0.38 | 0.060 |
| 1 | 1.00 | 1.06 | 2.62 | 2.06 | 1.81 | 3.56 | 0.94 | 6.88 | 2.06 | 1.50 | 1 - 8 | 2.41 | 1.62 | 0.44 | 0.095 |
| 1 1/8 | 1.12 | 1.12 | 2.75 | 2.23 | 1.94 | 4.06 | 1.00 | 7.31 | 2.31 | 1.69 | 1 1/8 - 7 | 2.59 | 1.69 | 0.44 | 0.060 |
| 1 1/8 | 1.12 | 1.19 | 2.88 | 2.26 | 2.06 | 4.06 | 1.06 | 7.69 | 2.31 | 1.69 | 1 1/8 - 7 | 2.78 | 1.81 | 0.50 | 0.095 |
| 1 1/4 | 1.25 | 1.25 | 3.00 | 2.38 | 2.12 | 4.44 | 1.12 | 8.06 | 2.50 | 1.88 | 1 1/4 - 7 | 2.84 | 1.88 | 0.50 | 0.060 |
| 1 1/4 | 1.25 | 1.34 | 3.12 | 2.50 | 2.25 | 4.44 | 1.19 | 8.44 | 2.50 | 1.88 | 1 1/4 - 7 | 3.03 | 2.00 | 0.56 | 0.095 |
| 1 1/2 | 1.50 | 1.50 | 3.50 | 2.75 | 2.44 | 5.19 | 1.31 | 9.22 | 3.00 | 2.25 | 1 1/2 - 6 | 3.19 | 2.12 | 0.50 | 0.060 |
| 1 1/2 | 1.50 | 1.59 | 3.62 | 2.87 | 2.56 | 5.19 | 1.38 | 9.56 | 3.00 | 2.25 | 1 1/2 - 6 | 3.44 | 2.25 | 0.62 | 0.095 |
| 1 3/4 | 1.75 | 1.75 | 3.75 | 3.18 | 2.75 | 6.00 | 1.50 | 10.47 | 3.19 | 2.62 | 1 3/4 - 5 | 3.88 | 2.50 | 0.50 | 0.060 |
| 1 3/4 | 1.75 | 1.84 | 3.88 | 3.31 | 3.00 | 6.00 | 1.56 | 10.88 | 3.19 | 2.62 | 1 3/4 - 5 | 4.12 | 2.62 | 0.62 | 0.095 |
| 2 | 2.00 | 2.00 | 4.00 | 3.62 | 3.06 | 6.88 | 1.75 | 11.62 | 3.38 | 3.00 | 2 - 4 1/2 | 4.25 | 2.88 | 0.62 | 0.060 |
| 2 | 2.00 | 2.09 | 4.12 | 3.79 | 3.44 | 6.88 | 1.88 | 12.12 | 3.38 | 3.00 | 2 - 4 1/2 | 4.50 | 3.00 | 0.75 | 0.095 |
| Nominal Size | Thread Size | Breaking Strength Min (lbf) | Proof Load Min (lbf) | Rated Capacity @ 0° (lbf) | Rated Capacity @ 30° (lbf) | Rated Capacity @ 60° (lbf) | Rated Capacity @ 90° (lbf) |
|---|---|---|---|---|---|---|---|
| 1/4 | 1/4 - 20 | 2100 | 800 | 400 | 70 | NR | NR |
| 5/16 | 5//16 - 18 | 3400 | 1360 | 680 | 200 | NR | NR |
| 3/8 | 3/8 - 16 | 5000 | 2000 | 1000 | 375 | 200 | 155 |
| 7/16 | 7/16 - 14 | 6900 | 2760 | 1380 | 500 | 300 | 235 |
| 1/2 | 1/2 - 13 | 9200 | 3680 | 1840 | 805 | 470 | 395 |
| 9/16 | 9/16 - 12 | 11830 | 4740 | 2370 | 1105 | 635 | 520 |
| 5/8 | 5/8 - 11 | 14700 | 5880 | 2940 | 1340 | 805 | 670 |
| 3/4 | 3/4 - 10 | 21700 | 8680 | 4340 | 2115 | 1190 | 1040 |
| 7/8 | 7/8 - 9 | 30000 | 12000 | 6000 | 2815 | 1740 | 1475 |
| 1 | 1 - 8 | 39400 | 15760 | 7880 | 3670 | 2390 | 2110 |
| 1 1/8 | 1 1/8 - 7 | 49600 | 19840 | 9920 | 4660 | 3010 | 2610 |
| 1 1/4 | 1 1/4 - 7 | 63000 | 25200 | 12600 | 5896 | 3752 | 3350 |
| 1 1/2 | 1 1/2 - 6 | 91600 | 36520 | 18260 | 8575 | 5495 | 4960 |
| 1 3/4 | 1 3/4 - 5 | 123500 | 49400 | 24700 | 11524 | 7500 | 6700 |
| 2 | 2 - 4 | 162500 | 65000 | 32500 | 15210 | 9915 | 8800 |
- Row 2 (5/16): The 5/16 row's thread prints "5//16 - 18" in the source — a typo token for 5/16 - 18, reproduced verbatim.
- Row 1 (1/4): At 1/4 and 5/16 the 60° and 90° rated capacities print "NR" (not rated) — these angles are outside the plain pattern's rating at small sizes. The proof-load and rated-capacity cells print without an explicit unit in the tabulated data; the lbf scale follows the breaking-strength column. Verify against ASME B30.26 rigging practice before lifting use — a rated capacity is a de-rating rule, not a strength figure.
- Row 15 (2): The capacity ladder stops at 2 in while the dimension tables on this page run to 2 1/2 in — the source calculator did not return capacity for 2 1/2; capacity for that size is not established here.
Materials
- Material, capacity rating and finish specified per RFQ — forged carbon steel is the class default, but capacity and finish are confirmed at quotation, not assumed from the dimension tables
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (ASME B18.15 Forged Eye Bolts (Inch Series, Plain and Shoulder Patterns)) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantity is 1,000–10,000 pieces depending on size. Stock items run 3–7 days. High-strength and custom parts run 15–25 days. Quantities or variants outside the standard range are confirmed at quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
Plain pattern or shoulder pattern eye bolt — and why does the shoulder matter for angular loading?
It comes down to the direction of pull. A plain pattern eye bolt is dimensioned for a straight tensile load along the shank axis: pull it sideways even modestly and the bending moment at the shank-eye transition multiplies stress far beyond what the geometry suggests, which is why the standard and safe-use guidance forbid angular loading on plain pattern parts. The shoulder pattern solves this mechanically rather than by caution: the machined shoulder (the J/K/R columns in the collected table) must be fully seated against a flat mating surface, and the shoulder then carries the bending moment, permitting limited angular loading — "limited" because capacity still falls as the angle moves away from the shank axis, and the rated capacities are set by the manufacturer, not by the dimension tables on this page. Practically: if the pull is guaranteed axial and in-line, either pattern works and the plain table covers sizes to 2 1/2 in; if there is any chance of side pull — most real rigging — the shoulder pattern seated flush is the correct choice. Two ordering details from the tables: each nominal size has two geometry rows (regular and heavier section), so specify the row, not just the size; and check the wrench/thread column — all threads are UNC-2A across both tables.
What is the MOQ and lead time for this bolt type?
The minimum order quantity is 1,000–10,000 pieces depending on size. Stock items ship in 3–7 days; high-strength and custom parts in 15–25 days. Common sizes in this bolt type are widely stocked; confirm the exact schedule against quantity and size mix at quotation.
Related knowledge
- What Bolt Property Classes 8.8, 10.9 and 12.9 Encode — and When High Strength Stops Being the Right Choice
- Bolt Grade Selection: ISO 898-1 8.8/10.9/12.9 vs ASTM A307 and A325
- 8.8 vs 10.9 vs 12.9 Bolts: Strength, Hardness and Cost — What the Evidence Settles
- Calculating Bolt Preload and Clamp Force: Torque, Friction and Tightening Method
- How to Determine Tightening Torque and Choose a Tightening Method for a Bolted Joint
- Fastener Failure Modes: Which Fatigue, Creep and SCC Controls the Evidence Supports
- Hydrogen Embrittlement in High-Strength Bolts: Which Grades Need Controls, Which Coatings and Baking Schedules Are Acceptable, and What to Require Before the RFQ
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support