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ASME B107.9M-1994 — Wrenches, Box, Angled, Open End, Combination, Flare Nut, and Tappet (Metric Series)
🔧 ASME B107.9M-1994 is the comprehensive ASME B107 family standard for fixed wrenches in the metric series, covering box wrenches, angled wrenches, open-end wrenches, combination wrenches, flare nut wrenches, and tappet wrenches — seven types in all. It provides complete general and dimensional data for each type and is a key reference for selecting, accepting, and inspecting fixed wrenches in automotive service, aerospace assembly, and industrial maintenance; its inch-series sibling is B107.6. The Standard also carries a January 1996 Errata issued as replacement pages, correcting certain dimension tables and callouts.
💡 The 1996 Errata is issued as replacement pages: users replace the affected pages per the errata list and are advised to keep this cover page for reference. When using or inspecting to the Standard, verify the copy in hand incorporates the corrections (e.g., corrected drawing callouts and gage spelling).
1. Scope and Product Classification 📌
The Standard covers seven fixed-wrench Types, each subdivided by Class and Style to suit different fastening and access conditions:
- Type I — Box wrench: double head; Class 1 with 15° offset each end, Class 2 with deep or modified offset; regular and short lengths.
- Type II — Engineers wrench: double-head open end, 15° offset.
- Type III — Combination wrench: open end on one side and a 15° offset box opening on the other; regular, short, and long styles.
- Type IV — Flare nut wrench: double-head open end for flare (tube) nuts.
- Type V — Flare nut combination wrench: open end plus 15° offset box end.
- Type VI — Angle wrench: double-head open end; Style 1 at 15°/60°, Style 2 at 30°/60°.
- Type VII — Tappet wrench: double-head open end, 15° offset, for valve-tappet adjustment work.
⚠️ The head angles (15°/30°/60°) of angled and offset wrenches are deliberate: the angle dictates flip-over reachability in confined spaces, so match the head-angle combination to the fastener position and rotation arc.
2. Technical Requirements and Specifications 📏
Section 4 specifies materials, marking, hardness, proof loads, wrench opening, and finish; extensive tables give opening sizes, overall lengths, head thicknesses, and offset angles for every type and size. Core requirements are summarized below:
| Type | Head Configuration | Head Angles | Length / Class | Typical Use |
|---|---|---|---|---|
| Type I Box | Double-head closed | 15° / deep offset | Regular, short | High-torque slip-resistant turning |
| Type II Engineers | Double-head open end | 15° | Fixed series | General fast run-up |
| Type III Combination | Open end + box end | Open end / box 15° | Regular, short, long | General maintenance |
| Type IV Flare nut | Double-head open end | — | Fixed series | Hydraulic/brake tube nuts |
| Type V Flare nut comb. | Open end + box end | Box 15° | Fixed series | Line assembly work |
| Type VI Angle | Double-head open end | 15°/60° or 30°/60° | Style 1 / Style 2 | Crank and connecting-rod access |
| Type VII Tappet | Double-head open end | 15° | Class 1 | Engine valve adjustment |
On hardness, wrenches shall be heat treated to not less than 38 HRC nor more than 55 HRC (Brinell 353–547 HB) — enough strength and wear resistance without brittleness. Wrench openings must conform to the gages of ASME B107.17M. Each wrench (except Type III combination) shall be marked on a face or the handle, as close to each head as practicable, with the respective nominal wrench opening, plus the manufacturer’s name or trademark so the source and country of origin can be determined.
💡 The wide 38–55 HRC window balances serviceability and durability: below 38 HRC tools wear and distort quickly; above 55 HRC they become brittle. Hardness is verified per ASTM E18.
3. Proof Loads and Test Procedures 🔬
- Hardness test: per ASTM E18 and ASTM E10 (Brinell) with properly prepared surfaces.
- Proof-load test: per the applicable tables — the wrench must withstand the proof load without failure or permanent deformation affecting durability or serviceability; test mandrels shall be hardened to not less than 55 HRC and smoothly finished on the engaging surfaces.
- Workmanship: surfaces thoroughly clean, free from cracks, and essentially free from burrs, pits, and other detrimental deficiencies.
🚨 Proof-load testing has an explicit mandrel hardness requirement (≥55 HRC): an unhardened mandrel will dent under load and distort the test. Always use compliant hardened mandrels and the fixture position shown in the figures.
4. Engineering Practice Essentials 🛠️
- 🔍 Selection: choose box or the box end of combination wrenches for high torque; flare-nut types for tube fittings; angled or short-length wrenches in tight spaces.
- 🔧 Torque management: respect the proof-load tables; never overload or extend leverage with an over-length pipe.
- 📊 Space use: 60° heads keep turning possible with minimal swing, ideal for connecting rods and crankshafts with limited arc.
- 📋 Receiving inspection: verify size and manufacturer markings, spot-check hardness and opening gage conformance, and retain records.
Because the Standard covers seven types, a few practical conventions keep a tool crib manageable. Combination wrenches (Type III) are the workhorse and justify the largest set. Dedicated flare-nut wrenches should be kept near tube fittings and hydraulic benches so a plain open-end wrench is not used in their place. Tappet wrenches are typically sold in thin-blade form for valve adjustment and should not be used for general service where a heavier wrench is appropriate. Marking each wrench with its nominal opening size helps users reach for the correct size without trial and error, and makes the mandated size and source markings easy to audit during inspection.
5. Frequently Asked Questions ❓
❓ Q: How do I choose between the 15°/60° and 30°/60° angle wrenches?
A: The 60° head guarantees continued turning with minimal back-swing; the 15° or 30° head sets the initial approach angle. The tighter the surrounding obstruction, the more the head-angle combination matters.
A: The 60° head guarantees continued turning with minimal back-swing; the 15° or 30° head sets the initial approach angle. The tighter the surrounding obstruction, the more the head-angle combination matters.
❓ Q: How is a flare nut wrench different from a plain open-end wrench?
A: A flare nut wrench forms a near-complete hex ring with a side slot that lets the tube pass through, so it grips the flare nut without crushing the line — the dedicated tool for hydraulic, brake, and fuel fittings.
A: A flare nut wrench forms a near-complete hex ring with a side slot that lets the tube pass through, so it grips the flare nut without crushing the line — the dedicated tool for hydraulic, brake, and fuel fittings.
🔍 Q: Why must wrenches carry a “nominal opening size” mark?
A: The nominal size is the fastener across-flats dimension; a clear, permanent mark speeds field matching and enables receiving traceability to the manufacturer and country of origin — a mandatory marking requirement.
A: The nominal size is the fastener across-flats dimension; a clear, permanent mark speeds field matching and enables receiving traceability to the manufacturer and country of origin — a mandatory marking requirement.
🔧 Q: Does the 1996 Errata affect users?
A: Yes. It corrected, among others, the Table 10B title (Type VI, Style 1, Angle Wrench, 15° and 60°), “gauge”→”gage,” and a Max./Min. column mislabel; using the errata-incorporated copy avoids accepting parts to wrong dimensions.
A: Yes. It corrected, among others, the Table 10B title (Type VI, Style 1, Angle Wrench, 15° and 60°), “gauge”→”gage,” and a Max./Min. column mislabel; using the errata-incorporated copy avoids accepting parts to wrong dimensions.
