ASME B107.100-2010 — Flat Wrenches (Combination, Box, Open End, Adjustable)

28 10 月, 2026
ASME Standards

🔧 ASME B107.100-2010 is the consolidated standard within the ASME B107 “Hand Tools and Accessories” family that covers flat wrenches. Through a process of “revision and incorporation,” it brings seven formerly separate wrench standards into a single document: B107.6 (Combination Wrenches), B107.8 (Adjustable Wrenches), B107.9 (Box Wrenches, Double Head), B107.21 (Wrench, Crowfoot), B107.39 (Open End Wrenches, Double Head), B107.40 (Wrenches, Flare Nut), and B107.66 (Ratcheting Box Wrenches). First issued as “Wrenches” in 2002, this edition is redesignated “Flat Wrenches” and adds B107.8, B107.21, and B107.66. It was approved as an American National Standard on March 11, 2010.

💡 The value of B107.100 is “one standard for one tool family”: procurement, acceptance, and quality systems can reference a single document to cover the whole family of flat wrenches, avoiding the version and clause conflicts that arise when several standards coexist.

1. Scope and General Framework 📌

This Standard defines essential performance and safety requirements for combination wrenches, double-head box wrenches, double-head open end wrenches, flare nut wrenches, adjustable wrenches, crowfoot wrenches, and ratcheting box wrenches. It specifies test methods for evaluating performance and safety and indicates the limitations of safe use. Each product chapter follows a uniform structure — definitions, references, performance requirements, tests, and safety requirements and limitations of use — making the document easy to navigate.

Compared with the prior separate standards, the principal changes are the uniform inclusion of performance requirements and test methods that evaluate both performance and safety, plus a uniform format across all product sections. The product-specific dimensional data are retained, with inch and metric tables given side by side (e.g., Tables 1/1M, 2/2M).

2. Products Covered 🔩

Source Standard	Product	Key Feature	Typical Size Range
B107.6	Combination wrenches	Open end at one end, box end at the other	1/4–2 in and metric equivalents
B107.8	Adjustable wrenches	Worm-gear adjustable jaw	4–24 in length classes
B107.9	Box wrenches, double head	12-point box at both ends	1/4–2 in
B107.21	Crowfoot wrenches	Open-end head used with a handle	1/4–1-1/4 in
B107.39	Open end wrenches, double head	Open end at both ends	1/4–2 in
B107.40	Flare nut wrenches	Slotted, enclosing open end	1/4–1-1/4 in
B107.66	Ratcheting box wrenches	Built-in ratchet in the box end	1/4–1-1/4 in

⚠️ Although the product chapters share a uniform format, their dimensional data, test torques, and safety requirements differ. Always consult the correct chapter for the product type (e.g., B107.6 for combination wrenches, B107.39 for open end wrenches) rather than treating them as interchangeable.

3. Performance Requirements and Test Methods 📊

The Standard specifies performance requirements for each wrench type; the core tests include:

Torque strength test: the open or box end is secured on a standard test mandrel and torque is progressively applied, verifying that no fracture or significant permanent deformation occurs at the specified maximum.
Hardness test: Rockwell hardness per ASTM E18 is used to verify the body hardness, balancing wear resistance and toughness.
Finish and coating inspection: adhesion and corrosion resistance are checked to confirm appearance and rust protection.
Ratchet function test (B107.66 only): verifies reliable reversing and functional retention after repeated use.

The mandrel dimensions and maximum insertion depths are given in the Standard (e.g., Tables 2/2M) so that results are comparable across laboratories. Performance requirements also cover dimensional and geometric tolerances such as opening size, thickness, length, and parallelism.

4. Safety Requirements and Limitations of Use 🛡️

The uniform safety section includes the following points:

Wrenches are for hand service only; unless the product is rated for power drive, they must not be used with impact tools.
Never slip a cheater bar over a wrench to increase torque — an open end wrench can slip or spring open under overload and cause injury.
Operate an adjustable wrench so that the load is taken on the fixed jaw side.
Match the wrench size exactly to the fastener; a loose fit will easily slip and damage both the fastener and the wrench.

🚨 Safety warning: improper loading of an open end wrench (reversed force, excessive jaw spread) can cause a sudden slip or a jam on the fastener corner; the released torque can easily injure the wrist. Always pull rather than push, and apply force in the correct direction.

5. Engineering Practice Essentials 🛠️

🔍 Set composition: a general maintenance set usually centers on combination wrenches from 6 to 24 mm (metric) and 1/4 to 1 in (inch), supplemented by box wrenches, an adjustable wrench, and ratcheting box wrenches to cover different torque and access needs.
🔧 Open end vs. box: an open end slips on and off quickly; a box end wraps the fastener for better anti-slip and is suited to high torque and damaged bolt heads.
📋 Acceptance: verify size marking and dimensions, check opening parallelism and coating, and sample-test hardness and torque strength reports.
📊 Maintenance: clean and oil after use to prevent opening wear that causes slipping; periodically lubricate ratcheting wrench mechanisms.

6. Frequently Asked Questions ❓

❓ Q: How does B107.100-2010 relate to the old separate B107.6 etc. standards?
A: B107.100 incorporates and supersedes B107.6, B107.8, B107.9, B107.21, B107.39, B107.40, and B107.66. When citing the current document, cite B107.100 rather than the superseded individual standards.

❓ Q: Why were the old wrench standards consolidated?
A: To unify the format, reduce maintenance effort, and align performance requirements and test methods across all wrench categories.

🔍 Q: What is the difference between a flare nut wrench and an ordinary open end wrench?
A: A flare nut wrench has a slotted, enclosing opening that fits fully over a tube-fitting nut without crushing the tube, making it suitable for hydraulic lines; an ordinary open end wrench is fully open for fast slip-on work.

❓ Q: How do I choose between a combination wrench and a ratcheting box wrench?
A: A combination wrench (open + box) is the most versatile and cost-effective; a ratcheting box wrench avoids repeated removal and re-seating, ideal for repetitive nut-running, but costs more and is more complex.

ASME B107.100-2010.pdf