STUD BOLT FOR FLANGES

BOLTING SET DEFINITION

A stud bolt set consists of a fully threaded steel rod and 2 matching heavy hex nuts (having 6 sides each). Within the petrochemical and power generation industries, stud bolts are widely used for flanged joints. Stud bolts are available in a variety of materials from carbon steel to alloy, stainless and nickel alloys. The material choosen for the threaded stud and the associated nuts, should be compatible.

Stud bolts for flanges

 

Threaded rod stud bolts The stud length equals the effective threaded length measured parallel to the axis, starting from the first thread excluding the chamfers. 

ASME B1.1 norm defines the threading specs. The most used thread is the symmetrical type with a V-profile (that features a 60 deg. angle), as it is easier to manufacturer and inspect compared to the non-symmetrical types. Thread series relate to the diameter and pitch combinations, measured by the number of threads per inch (TPI) applied to a single diameter.

The standard thread pitches are:

  • Coarse thread series (UNC/UNRC): this is the most common type which is used for most screws, bolts, and nuts. Coarse threads are adopted for threads in low strength materials such as iron, mild steel, copper and softer alloy, aluminum, etc. The coarse thread is also more tolerant in adverse conditions and it facilitates quick assembly
     
  • Fine thread series (UNF/UNRF) is widely used for precision duties and when a higher tensile strength is required (vs. the coarse thread series)
     
  • 8-Thread series (8UN) is the elective threading method for multiple ASTM standards including A193 B7, A193 B8/B8M, and A320. This series is widely used for diameters from one inch upwards

What is the difference between screws, bolts and studs?

Bolts, Studs and Screws

BOLT CHARTS

The number of bolts required by a flanged connection, as well as the lenght and the diameter of the bolts, depends on the flange diameter and class (the higher the class, the greater the number of holes), as shown in the following tables taken from ASME B16.5:

ASME B 16.5 RF AND RTJ FLANGES – CLASS 150

NPS BOLTS DIAMATER in. LENGHT RF LENGHT
RTJ
BOLTS NUMBER   NPS BOLTS DIAMATER in. LENGHT RF LENGHT
RTJ
BOLTS NUMBER
1/2 1/2 55 ... 4 5 3/4 95 110 8
3/4 1/2 65 .. 4 6 3/4 100 115 8
1 1/2 65 75 4 8 3/4 110 120 8
1.1/4 1/2 70 85 4 10 7/8 115 125 12
1.1/2 1/2 70 85 4 12 7/8 120 135 12
2 5/8 85 95 4 14 1 135 145 12
2.1/2 5/8 90 100 4 16 1 135 145 16
3 5/8 90 100 4 18 1.1/8 145 160 16
3.1/2 5/8 90 100 8 20 1.1/8 160 170 20
4 5/8 90 100 8 24 1.1/4 170 185 20

 

ASME B 16.5 RF AND RTJ FLANGES – CLASS 300

NPS BOLTS DIAMATER in. LENGHT
RF
LENGHT
RTJ
BOLTS NUMBER   NPS BOLTS DIAMATER in. LENGHT
RF
LENGHT
RTJ
BOLTS NUMBER
1/2 1/2 65 75 4 5 3/4 120 135 8
3/4 5/8 75 90 4 6 3/4 120 140 12
1 5/8 75 90 4 8 7/8 140 150 12
1.1/4 5/8 85 95 4 10 1 160 170 16
1.1/2 3/4 90 100 4 12 1.1/8 170 185 16
2 5/8 90 100 8 14 1.1/8 180 190 20
2.1/2 3/4 100 115 8 16 1.1/4 190 205 20
3 3/4 110 120 8 18 1.1/4 195 210 24
3.1/2 3/4 110 125 8 20 1.1/4 205 220 24
4 3/4 115 125 8 24 1.1/2 230 255 24

 

ASME B 16.5 RF AND RTJ FLANGES - CLASS 400

NPS BOLTS DIAMATER in. LENGHT
RF
LENGHT
RTJ
BOLTS NUMBER   NPS BOLTS DIAMATER in. LENGHT
RF
LENGHT
RTJ
BOLTS NUMBER
1/2 1/2 75 75 4 5 7/8 145 145 8
3/4 5/8 90 90 4 6 7/8 150 150 12
1 5/8 90 90 4 8 1 170 170 12
1.1/4 5/8 95 95 4 10 1.1/8 190 190 16
1.1/2 3/4 110 110 4 12 1.1/4 205 205 16
2 5/8 110 110 8 14 1.1/4 210 210 20
2.1/2 3/4 120 120 8 16 1.3/8 220 220 20
3 3/4 125 125 8 18 1.3/8 230 230 24
3.1/2 7/8 140 140 8 20 1.1/2 240 250 24
4 7/8 140 140 8 24 1.3/4 265 280 24

 

ASME B 16.5 RF AND RTJ FLANGES - CLASS 600

NPS BOLTS DIAMATER in. LENGHT
RF
LENGHT
RTJ
BOLTS NUMBER   NPS Diameter
bolts (in)
LENGHT
RF
LENGHT
RTJ
BOLTS NUMBER
1/2 1/2 75 75 4 5 1 165 165 8
3/4 5/8 90 90 4 6 1 170 170 12
1 5/8 90 90 4 8 1.1/8 190 195 12
1.1/4 5/8 95 95 4 10 1.1/4 215 215 16
1.1/2 3/4 110 110 4 12 1.1/4 220 220 20
2 5/8 110 110 8 14 1.3/8 235 235 20
2.1/2 3/4 120 120 8 16 1.1/2 255 255 20
3 3/4 125 125 8 18 1.5/8 275 275 20
3.1/2 7/8 140 140 8 20 1.5/8 285 290 24
4 7/8 145 145 8 24 1.7/8 330 335 24

 

ASME B 16.5 RF AND RTJ FLANGES - CLASS 900

NPS BOLTS DIAMATER in. LENGHT
RF
LENGHT
RTJ
BOLTS NUMBER   NPS BOLTS DIAMATER in. LENGHT
RF
LENGHT
RTJ
BOLTS NUMBER
1/2 3/4 110 110 4 6 1.1/8 190 195 12
3/4 3/4 115 115 4 8 1.3/8 220 220 12
1 7/8 125 125 4 10 1.3/8 235 235 16
1.1/4 7/8 125 125 4 12 1.3/8 255 255 20
1.1/2 1 140 140 4 14 1.1/2 275 280 20
2 7/8 145 145 8 16 1.5/8 285 290 20
2.1/2 1 160 160 8 18 1.7/8 325 335 20
3 7/8 145 145 8 20 2 350 360 20
4 1.1/8 170 170 8 24 2.1/2 440 455 20
5 1.1/4 190 190 8          

 

ASME B 16.5 RF AND RTJ FLANGES - CLASS 1500

NPS BOLTS DIAMATER in. LENGHT
RF
LENGHT
RTJ
BOLTS NUMBER   NPS BOLTS DIAMATER in. LENGHT
RF
LENGHT
RTJ
BOLTS NUMBER
1/2 3/4 110 110 4 6 1.3/8 260 265 12
3/4 3/4 115 115 4 8 1.5/8 290 300 12
1 7/8 125 125 4 10 1.7/8 335 345 12
1.1/4 7/8 125 125 4 12 2 375 385 16
1.1/2 1 140 140 4 14 2.1/4 405 425 16
2 7/8 145 145 8 16 2.1/2 445 470 16
2.1/2 1 160 160 8 18 2.3/4 495 525 16
3 1.1/8 180 180 8 20 3 540 565 16
4 1.1/4 195 195 8 24 3.1/2 615 650 16
5 1.1/2 250 250 8          

 

ASME B 16.5 RF AND RTJ FLANGES - CLASS 2500

NPS BOLTS DIAMATER in. LENGHT
RF
LENGHT
RTJ
BOLTS NUMBER     NPS BOLTS DIAMATER in. LENGHT
RF
LENGHT
RTJ
BOLTS NUMBER
1/2 3/4 120 120 4 3 1.1/4 220 230 8
3/4 3/4 125 125 4 4 1.1/2 255 260 8
1 7/8 140 140 4 5 1.3/4 300 310 8
1.1/4 1 150 150 4 6 2 345 355 8
1.1/2 1.1/8 170 170 4 8 2 380 395 12
2 1 180 180 8 10 2.1/2 490 510 12
2.1/2 1.1/8 195 205 8 12 2.3/4 540 560 1

 

 

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