Skip to main content

Socket Shoulder Bolt

Selected Socket Cap Screw Shoulder Bolt Alloy BlackSocket Shoulder Bolt
Socket Cap Screw Shoulder Bolt Alloy BlackSocket Shoulder Bolt

ASTM A574 Socket Head Shoulder Bolts, sometimes called stripper bolts or just shoulder bolts, have a smooth shoulder that is larger than the thread diameter, running down the majority of the length of the fastener. The shoulder, having a larger diameter than the threads allows the fastener to be used in rotating applications such as pulley shafts, bearing pins, axles, and pivot points. The thread length is standard for a given diameter. Unlike most fasteners, socket head shoulder bolts are not sized by the thread diameter and length under the head, rather the diameter and length of the shoulder itself. Dimensional specifications are governed by ASME B18.3.

Products

Dimensional Specifications

Socket shoulder bolt dimensions
Per ASME B18.3-2003
Size Nominal D A H C J T M R
Shoulder
Diameter		 Head Diameter Head Height Chamfer
or Radius		 Hexagon
Socket Size		 Key
Engage-
ment		 Fillet
Transition
Diameter		 Head
Fillet
Radius
Max Min Max Min Max Min Max Nom Min Max Min
1/4 0.2500 0.2480 0.2460 0.3750 0.3570 0.1880 0.1770 0.0200 1/8 0.1250 0.0940 0.2760 0.0090
5/16 0.3120 0.3105 0.3085 0.4380 0.4190 0.2190 0.2090 0.0260 5/32 0.1560 0.1170 0.3450 0.0120
3/8 0.3750 0.3730 0.3710 0.5620 0.5430 0.2500 0.2400 0.0310 3/16 0.1880 0.1410 0.4130 0.0150
1/2 0.5000 0.4980 0.4960 0.7500 0.7290 0.3120 0.3020 0.0400 1/4 0.2500 0.1880 0.5500 0.0200
5/8 0.6250 0.6230 0.6210 0.8750 0.8530 0.3750 0.3650 0.0500 5/16 0.3120 0.2340 0.6870 0.0240
3/4 0.7500 0.7480 0.7460 1.0000 0.9770 0.5000 0.4900 0.0600 3/8 0.3750 0.2810 0.8260 0.0300
1 1.0000 0.9980 0.9960 1.3120 1.2870 0.6250 0.6100 0.0830 1/2 0.5000 0.3750 1.0980 0.0400
1 1/4 1.2500 1.2480 1.2460 1.7500 1.7230 0.7500 0.7350 0.1020 5/8 0.6250 0.4690 1.3680 0.0500
1 1/2 1.5000 1.4980 1.4960 2.1250 2.0950 1.0000 0.9800 0.1380 7/8 0.8750 0.6560 1.6380 0.0600
1 3/4 1.7500 1.7480 1.7460 2.3750 2.3450 1.1250 1.1050 0.1570 1 1.0000 0.7500 1.9080 0.0700
2 2.0000 1.9980 1.9960 2.7500 2.7200 1.2500 1.2300 0.1760 1 1/4 1.2500 0.9370 2.1780 0.0800
See Notes 1 8         6  
Size Nominal K F D1 G I N E P
Shoulder
Neck
Diameter		 Shoulder
Neck
Width		 Nominal
Thread
Diameter		 Threads
per
Inch		 Thread Neck
Diameter		 Thread
Neck Width		 Thread
Neck Fillet		 Thread
Length		 Chamfer
or
Radius
Min Max Max Min Max Max Min Basic Max
1/4 0.2500 0.2270 0.0930 #10 0.1900 24 0.142 0.133 0.083 0.023 0.017 0.375 0.010
5/16 0.3120 0.2890 0.0930 1/4 0.2500 20 0.193 0.182 0.100 0.028 0.022 0.438 0.010
3/8 0.3750 0.3520 0.0930 5/16 0.3125 18 0.249 0.237 0.111 0.031 0.025 0.500 0.010
1/2 0.5000 0.4770 0.0930 3/8 0.3750 6 0.304 0.291 0.125 0.035 0.029 0.625 0.010
5/8 0.6250 0.6020 0.0930 1/2 0.5000 13 0.414 0.397 0.154 0.042 0.036 0.750 0.015
3/4 0.7500 0.7270 0.0930 5/8 0.6250 11 0.521 0.502 0.182 0.051 0.045 0.875 0.015
1 1.0000 0.9770 0.1250 3/4 0.7500 10 0.638 0.616 0.200 0.056 0.049 1.000 0.020
1 1/4 1.2500 1.2270 0.1250 7/8 0.8750 9 0.750 0.726 0.222 0.062 0.056 1.125 0.020
1 1/2 1.5000 1.4780 0.1250 1 1/8 1.1250 7 0.964 0.934 0.286 0.072 0.066 1.500 0.020
1 3/4 1.7500 1.7280 0.1250 1 1/4 1.2500 7 1.089 1.059 0.286 0.072 0.066 1.750 0.020
2 2.0000 1.9780 0.1250 1 1/2 1.5000 6 1.307 1.277 0.333 0.102 0.096 2.000 0.020
See Notes 6 6 10   7 7 7    
  1. 1. Shoulder. Shoulder refers to the enlarged unthreaded portion of the screw, the diameter of which serves as the basis for derivation of the nominal size.
  2. 6. Neck and Fillet Under Head. Screws may be necked under the head at the option of the manufacturer. The fillet extension above D, at the intersection of the head bearing surface and neck or shoulder, shall be controlled by maximum dimension M and minimum radius of curvature R. (See Detail Y)
  3. 7. Neck Under Shoulder. The neck under the shoulder shall allow the shoulder to seat against the face of a standard basic GO thread ring gage.
  4. 8. Head Diameter. The head may be plain or knurled at the option of the manufacturer.
  5. 10. Threads. Threads shall be Unified external thread: Class 3A, UNC Series. Acceptability is to be based on System 22, ASME B1.3M. Class 3A does not provide a plating allowance. When plated products are required, it is recommended that they be procured from the manufacturer.

Mechanical Properties

Alloy Steel, Quenched & Tempered Per ASTM A574-13
Nominal
Diameter		 Full-Size Screws Machined Test Specimen Product
Hardness
Tensile
Strength		 Proof
Load		 Yield Strength
at 0.2% offset		 Tensile
Strength		 Elongation
in 5D		 Reduction
of Area
ksi ksi ksi ksi % % Rockwell
1/2" & under 180 min 140 153 min 180 min 10 min 35 min 39-45 HRC
over 1/2" 170 min 135 153 min 170 min 10 min 35 min 37-45 HRC

Governing Standards

ASTM A574 Covers the requirements for quenched and tempered alloy steel hexagon socket-head cap screws, 0.060 through 4 in. in diameter where high strength is required.
ASME B18.3 Covers the complete general and dimensional data for various types of hexagon socket cap screws, shoulder screws, set screws, and hexagon keys recognized as an American National Standard.
ASME B1.1 UNC & UNF Class 2A Specifies the thread form, series, class, allowance, tolerance, and designation for unified screw threads.

Alloy Steel Socket Shoulder Bolt Head Marking
Alloy Steel Socket Shoulder Bolt requires no material marking

Chemical Properties

Per ASTM A574-13
Material Heat Analysis Product Analysis
Carbon Phosphorus Sulfur Alloying
Elements		 Carbon Phosphorus Sulfur Alloying
Elements
% by weight % by weight % by weight % by weight % by weight % by weight
Quenched and
tempered alloy steel		 0.33 min 0.035 max 0.040 max (1) 0.31 min 0.040 max 0.045 max (1)
  1. 1. One or more of the following alloying elements: chromium, nickel, molybdenum, or vanadium shall be present in sufficient quantity to ensure that the specified strength properties are met after oil quenching and tempering. As a guide for selecting material, an alloy steel should be capable of meeting the specified mechanical requirements if the “as oil quenched” core hardness one diameter from the point is equal to or exceeds 25 HRC + (55 × carbon content).