ASME B107.2-2002 — Socket Wrenches, Extensions, Adaptors, and Universal Joints, Power Drive (Impact) (Inch Series)

28 10 月, 2026
ASME Standards

🔧 ASME B107.2-2002 is the hand-tool standard covering general and dimensional data for detachable socket wrenches, extensions, adaptors, and universal joints intended for power-drive impact use, in the Inch series. Developed by the ASME B107 Committee (Socket Wrenches and Drives), it provides a unified classification and dimensional specification for impact socket accessories used with pneumatic, electric, and hydraulic power tools, and serves as the basis for tool manufacturing, procurement, and quality inspection.

💡 The key difference from hand-use sockets: impact sockets must survive the huge transient torque of high-frequency impact loads, so they demand tougher materials, stricter hardness, and greater structural strength — never substitute a hand socket on an impact wrench.

1. Scope 📌

This Standard is intended to cover the complete general and dimensional data for detachable socket wrenches, extensions, adaptors, and universal joints for power-drive impact use. Inclusion of dimensional data does not imply that all products described are stock production sizes — consumers should consult manufacturers for stock size lists. All dimensions in this Standard are in inches.

⚠️ B107.2 covers only “Power Drive (Impact)” accessories; manual-use sockets belong to other B107 substandards (e.g., B107.110). Do not confuse the two when specifying.

2. Classification 🗂️

Products are classified systematically by Type and Class:

Type	Product	Class
Type I	Sockets — single hexagon (6-point) and double hexagon (12-point)	1 regular, 2 long, 3 extra long, 4 regular thin-wall, 5 long thin-wall
Type II	Sockets — single square (4-point) and double square (8-point)	1 regular, 2 long
Type III	Universal sockets — single and double hexagon	1 regular, 2 long
Type IV	Bars, extension	—
Type V	Adaptors	—
Type VI	Universal joint	—
Type VII	Sockets, #5 spline drive	1 regular, 2 long

3. Key Technical Requirements 🔬

3.1 Drive and Driven Ends

The square drive (power-tool side) and the square opening (fastener side) dimensions are the basis of interchangeability. The Standard references ASME B107.4M-1995, Driving and Spindle Ends for Portable Hand, Impact, Air and Electric Tools (percussion tools excluded), for drive-end requirements, and ASME B107.17M-1997, Gages, Wrench Openings, Reference, for wrench-opening gage verification. Common drive sizes include 1/4 in, 3/8 in, 1/2 in, 3/4 in, 1 in, 1-1/2 in, and #5 spline.

3.2 Hexagon vs. Double-Hexagon Openings

A 6-point socket contacts the full faces of the fastener head, distributing load evenly with strong anti-slip performance — ideal for high-torque impact duty. A 12-point socket can be engaged every 30°, convenient in tight spaces, but each contact area carries less surface, making it comparatively easier to slip under heavy impact torque.

💡 Field rule for impact use: choose 6-point whenever possible. 12-point sockets engage conveniently but concentrate stress at the corners under high impact torque, accelerating wear and even cracking over time.

4. Test Procedures and Quality Inspection 🧪

Section 5 of the Standard specifies test procedures, mainly:

Dimensional inspection: verify drive, opening, and overall length with standard gages.
Hardness inspection: body and drive end must fall within the specified hardness range, balancing wear resistance and toughness.
Strength/impact testing: apply impact loads per the procedure to confirm sockets, extensions, and universal joints neither permanently deform nor fracture under rated impact torque.

⚠️ Impact sockets are safety-related products. A broken socket can fly off at high speed and injure people — always use certified B107.2-compliant products and discard deformed, cracked, or worn sockets.

5. Application and Safe Use 🛠️

🔧 Matching selection: the drive size must match the tool’s drive end — e.g., a 1/2 in impact wrench takes 1/2 in drive impact sockets; adaptors change drive size but reduce torque efficiency and add runout.
⚠️ No cross-use: never mount hand sockets on impact tools; impact sockets can be used by hand but their wall thickness and design targets differ, and long-term cross-use accelerates wear.
📊 Universal joints: allow driving at an angle (typically within 15°–25°), but torque loss and reaction forces grow with angle — at steep angles reduce speed and impact count.
🧰 Maintenance: periodically clean dirt and oil from sockets and check openings for wear; recheck opening dimensions with a gage after long service.

🚨 Safety red line: confirm the fastener size matches the socket opening before work; never hold a socket by hand while the tool is rotating; on elevated work, tether sockets to prevent falling-tool injuries.

6. Frequently Asked Questions ❓

❓ Q: What is the difference between B107.2 and B107.110 (or B107.100)?
A: B107.2 is specifically for power-drive impact-use sockets and accessories (Inch series); B107.110 and similar substandards cover manual socket wrenches and accessories. Classification, dimensions, and tests differ — do not mix them.

❓ Q: Why are impact sockets more expensive than hand sockets?
A: Impact sockets must survive high-frequency impact loads and therefore use better alloys and heat treatment and pass strict impact-strength tests — manufacturing and inspection costs exceed those of ordinary hand sockets.

❓ Q: Are 12-point sockets weaker than 6-point sockets?
A: At the same material and wall thickness, 6-point sockets contact the fastener over a larger area with more uniform stress, giving better anti-slip and anti-deformation performance; 12-point trades some strength for engagement convenience. Prefer 6-point for heavy impact torque.

🔍 Q: How do I confirm an impact socket meets B107.2?
A: Compliant products mark the standard number (e.g., ANSI/ASME B107.2) and specifications on packaging or body; request a conformance statement and test report from the manufacturer, and verify key dimensions on site with standard gages.

ASME B107.2-2002.pdf