STS Industrial - Bolts & Screws

 

ASTM A320 GRADE L7 STUD BOLTS

GOVERNING STANDARDS:
ASTM A320/A320M Standard specification for alloy-steel and stainless steel bolting for low temperature service.
ASME B16.5 Covers recommended stud bolt quantity, diameter, and length for use in flanged pipe fittings.
ASME B1.1 Class 2A Specifies the thread form, series, class, allowance, tolerance, and desig nation for unified screw threads. UNC for 1″ diameter and smaller. UN8 (8 threads per inch) for 1-1/8″ diameter and larger.

 

APPLICATIONS:

A320 L7 stud bolts are intended for low temperature service. It has the same chemical and physical properties as ASTM A193 Grade B7, but must meet a Charpy impact value of 20 lb-ft at -150ºF to ensure satisfactory performance in low temperature services.

ASTM A320 Grade L7 Stud Bolt Marking

Product to be marked with the manufacturer’s marking and grade marking on one end of each stud 3/8″ diameter and larger. Manufacturer’s marking may be placed on other end if insufficient space. 

MATERIAL PROPERTIES:
AISI 4140/4142 Quenched and Tempered

DIAMETER

PROOF LOAD

YIELD STRENGTH

TENSILE STRENGTH

CORE HARDNESS

up through 2-1/2″

105,000 psi 125,000 psi

 Max

Elongation 16% Minimum (All Diameters)
Reduction of Area 50% Minimum (All Diameters)
Material strengths listed are minimum acceptable per governing standard. Core hardness based on Rockwell scale.

 

STUD REFERENCE CHART:

The chart below gives the recommended stud bolt diameter, length, and quantity for a given flange size.

FLANGE NOMINAL PIPE DIAMETER (in.)
RATING BOLTING 1/2 3/4 1 1-1/4 1-1/2 2 2-1/2 3 3-1/2 4
150# Number 4 4 4 4 4 4 4 4 8 8
Diameter 1/2 1/2 1/2 1/2 1/2 5/8 5/8 5/8 5/8 5/8
Stud Bolt Length 2-1/4 2-1/2 2-1/2 2-3/4 2-3/4 3-1/4 3-1/2 3-1/2 3-1/2 3-1/2
Mach Bolt Length 2 2 2-1/4 2-1/4 2-1/2 2-3/4 3 3 3 3
300# Number 4 4 4 4 4 8 8 8 8 8
Diameter  1/2  5/8  5/8  5/8  3/4  5/8  3/4  3/4  3/4  3/4
Stud Bolt Length 2-1/2 3 3 3-1/4 3-1/2 3-1/2 4 4-1/4 4-1/4 4-1/2
Mach Bolt Length 2-1/4 2-1/2 2-1/2 2-3/4 3 3 3-1/4 3-1/2 3-3/4 3-3/4
600# Number 4 4 4 4 4 8 8 8 8 8
Diameter  1/2  5/8  5/8  5/8  3/4  5/8  3/4  3/4  7/8  7/8
Stud Bolt Length 3 3-1/2 3-1/2 3-3/4 4-1/4 4-1/4 4-3/4 5 5-1/2 5-3/4
900# Number 4 4 4 4 4 8 8 8 8
Diameter  3/4  3/4  7/8  7/8 1  7/8 1 7/8 1-1/8
Stud Bolt Length 4-1/4 4-1/2 5 5 5-1/2 5-3/4 6-1/4 5-3/4 6-3/4
1500# Number 4 4 4 4 4 8 8 8 8
Diameter  3/4  3/4  7/8  7/8 1  7/8 1 1-1/8 1-1/4
Stud Bolt Length 4-1/4 4-1/2 5 5 5-1/2 5-3/4 6-1/4 7 7-3/4
2500# Number 4 4 4 4 4 8 8 8 8
Diameter  3/4  3/4  7/8 1 1-1/8 1 1-1/8 1-1/4 1-1/2
Stud Bolt Length 4-3/4 5 5-1/2 6 6-3/4 7 7-3/4 8-3/4 10
FLANGE NOMINAL PIPE DIAMETER (in.)
RATING BOLTING 5 6 8 10 12 14 16 18 20 24
150# Number 8 8 8 12 12 12 16 16 20 20
Diameter 3/4 3/4 3/4 7/8 7/8 1 1 1-1/8 1-1/8 1-1/4
Stud Bolt Length 3-3/4 4 4-1/4 4-1/2 4-3/4 5-1/4 5-1/4 5-3/4 6-1/4 6-3/4
Mach Bolt Length 3-1/4 3-1/4 3-1/2 4 4 4-1/2 4-1/2 5 5-1/2 6
300# Number 8 12 12 16 16 20 20 24 24 24
Diameter  3/4  3/4  7/8 1 1-1/8 1-1/8 1-1/4 1-1/4 1-1/4 1-1/2
Stud Bolt Length 4-3/4 4-3/4 5-1/2 6-1/4 6-3/4 7 7-1/2 7-3/4 8 9
Mach Bolt Length 4-1/4 4-1/4 4-3/4 5-1/2 5-3/4 6-1/4 6-1/2 6-3/4 7-1/4 8
600# Number 8 12 12 16 20 20 20 20 24 24
Diameter 1 1 1-1/8 1-1/4 1-1/4 1-3/8 1-1/2 1-5/8 1-5/8 1-7/8
Stud Bolt Length 6-1/2 6-3/4 7-1/2 8-1/2 8-3/4 9-1/4 10 10-3/4 11-1/4 13
900# Number 8 12 12 16 20 20 20 20 20 20
Diameter 1-1/4 1-1/8 1-3/8 1-3/8 1-3/8 1-1/2 1-5/8 1-7/8 2 2-1/2
Stud Bolt Length 7-1/2 7-1/2 8-3/4 9-1/4 10 10-3/4 11-1/4 12-3/4 13-3/4 17-1/4
1500# Number 8 12 12 12 16 16 16 16 16 16
Diameter 1-1/2 1-3/8 1-5/8 1-7/8 2 2-1/4 2-1/2 2-3/4 3 3-1/2
Stud Bolt Length 9-3/4 10-1/4 11-1/2 13-1/4 14-3/4 16 17-1/2 19-1/2 21-1/4 24-1/4
2500# Number 8 8 12 12 12
Diameter 1-3/4 2 2 2-1/2 2-3/4
Stud Bolt Length 11-3/4 13-1/2 15 19-1/4 21-1/4

 

 

All dimensions in inches unless otherwise noted.

Sources: ASTM Standards for Mechanical Fasteners and Related Processes 2nd Edition, Inch Fastener Standards 8th Edition

Note: All material included on this page is informational only, and should not be used as one’s sole source for design purposes. STS Industrial, Inc. and its affiliates do not guarantee the accuracy of the information on this site, and retain no liability for the use or misuse of the information contained on this site.