Stud Bolts

Shop All Studs MSI Thread Pitch Chart MSI's Bolt Chart

Stud bolts, a term used for cut-to-length all thread rod, are used for: bolting together flanges, anchor bolting, as well as general fastening. 

MSI is a stud bolt distributor, offering stud bolts in carbon, stainless, along with several special alloys. With stud bolt diameters ranging from 1/2” to 4", MSI can provide the stud bolts required for virturally any project.

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Inventory

MSI Supply stocks B7 stud bolts from 1/2” - 2” diameter in: Plain (black) finish, Teflon Blue, and Cad Plating.  MSI also stocks B8 and B8M stud bolts from ¼ - 1-1/2”.  MSI can also provide larger stud bolts, stud bolts made from different materials (B8, B8M, Alloy 20, Monel, Hastelloy, Inconel, Titanium, etc), as well as different coatings. While many of the larger diameter items can be made available for a next-day delivery, some of the special alloys and coatings may be subject to a longer lead time.  The table below shows a look at not just the stud bolts MSI has in inventory, but what MSI is capable of providing.

Size Range: 1/4" to 4" Diameter (Metric & Standard)
Types: All Thread, Double End, Single End
Carbon Steel: B7, B7M, L7
Stainless Steel: B8, B8 CL2, B8M, B8M CL2, B16
Exotic Alloys: A2017-4PH, MonelInconelIncoloyHastelloy
Coatings: Black Oxide, Cadmium, Galvanized, Teflon, Xylan, Zinc, Others Upon Request

Thread Pitch

Thread pitch refers to the steepness of the angle of thread, which is measured in threads per inch.  MSI’s Thread Pitch Chart shows the unified screwed thread for coarse and fine thread, as well as the thread pitch for stud bolts. Stud bolts covered under the A193 or A320 ASTM Specifications utilize 8UN for all diameters 1” and above, meaning there are 8 threads per inch for these sizes. All other materials should be specified by the purchaser unless noted in the ASTM spec given.

Length

Length can be measured one of two ways, either overall length (OAL) or first useable thread to first useable thread (FTF). Industry standard and MSI stock is measured OAL. To find FTF measurement from OAL, simply subtract a quarter of an inch.

Stud Bolt chart showing overall length vs first to first

Material

Stud bolts can be made from many different grades of material, but the most common materials are listed below.  The A193 and A320 pages provide the chemical and mechanical properties of these material grades below.  

Carbon Steel

A193 B7 – This is the most common grade for which stud bolts are produced.  B7 is a Chrome-moly, Alloy steel that is made to AISI 4140/4142, and it is quenched and tempered.

A193 B7M – The “M” here stands for Modified (heat treated) B7 material

A193 B16 - Chrome-moly-vanadium, Alloy steel, AISI 4140/4142 quenched and tempered

A320 L7 - AISI 4140/4142 quenched and tempered Alloy steel

A320 L43 - AISI 4340 quenched and tempered Alloy Steel

Stainless Steel

A193 B6 – Heat treated 410 stainless (410HT)

A193 B8 – Produced to grade AISI 304, carbide solution treated, standardly available in class 1

A193 B8M – Produced to grade AISI 316, carbide solution treated, standardly available in class 1

A193 B8C- Grade 347 stainless material

A193 B8T – Grade 321 stainless material

A320 B8 - Produced to grade AISI 304, carbide solution treated, standardly available in class 1

A320 B8M - Produced to grade AISI 316, carbide solution treated, standardly available in class 1

A193 vs A320

A193 is the ASTM standard covering alloy and stainless steel bolting materials for high temperature or high-pressure service. This specification includes fasteners intended for use in pressure vessels, valves, flanges, and fittings. Material selection depends on design, service conditions, mechanical properties, and temperature characteristics. This material is often available in UNC thread pitches. If being used in traditional applications, threads are specified 8 threads per inch or 8UN for diameters above one inch.

A320 is the ASTM specification covering alloy steel and stainless bolting materials used in low-temperature services. A320 covers rolled, forged, or strain hardened bars, bolts, and stud bolts used for pressure vessels, valves, flanges, and fittings. As in A193, UNC threads are available but 8UN is standard on fasteners larger than 1" in diameter.

Bolt chart for flanges by class can be seen here.

CLASS 1 VS CLASS 2 STUD BOLTS

Class 1 stud bolts are made from solution-treated material. Class 2 stud bolts are made from solution-treated material that has been strain hardened. Austenitic steels in the strain hardened condition may not show uniform properties throughout the cross section, particularly in stud bolt sizes over 3/4" diameter.  For instance, A193 B8 and B8M stud bolts are standardly provided as class 1 but are also available in class 2.

DUAL CERTIFIED STUD BOLTS

Many stud bolts are provided as "dual certified," meaning they conform to multiple sets of ASTM standards. Example: A193 B7 stud bolts can meet the requirements of A320 L7; B8 and B8m stud bolts also typically conform to both A193 and A320.

Related Hardware

This chart shows the nuts and washers that accompany the stud bolts outlined here.  These items are required for proper installation.

Stud Bolt Grade

Nuts

Washers

L7

A194 Grade 4 or 7

F436

L43

A194 Grade 4 or 7

F436

B8 Class 1

A194 Grade 8

SS304

B8M Class 1

A194 Grade 8M

SS316

B8 Class 2

A194 Grade 8

SS304

B8M Class 2

A194 Grade 8M

SS316

B7

A194 Grade 2H

F436

B7M

A194 Grade 2HM

F436

B16

A194 Grade 4 or Grade 7

F436

 

Coating and Plating Stud Bolts

Stud bolts are most commonly available with a plain finish, which is also referred to as Black.  However, there are also numerous applications that call for coating/plating, with the most common Teflon Blue coating.  Teflon, or Xylan, coating provides for increased corrosive resistance, which is favorable that require increased corrosion resistance as well as the strength of B7 material.

Stud Bolt Coating and plating chart showing teflong blue, cad plated, zinc, and more