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ASME B16.5 · Class 150–2500 · RF & RTJ

Flange Bolting Stud Bolts Manufacturer in India

A full-thread stud and two heavy hex nuts for every bolt hole. We make flange bolting stud bolts for ASME B16.5 flanges in A193 B7 with 2H nuts, B7M, L7, B8M and nickel alloys, plain or PTFE coated. Below: the stud size map, a stud chart for every class with RF and RTJ lengths, how length is measured and a finder that counts studs and nuts for your joints.

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  • ISO 9001:2015 certified manufacturer
  • Complete stud & nut sets
  • Class 150 to 2500
  • EN 10204 3.1 / 3.2
Stud bolt with two heavy hex nuts for flange bolting
Classes 150 – 2500 NPS 1/2 – 24 Studs 1/2 – 3-1/2 in
Overview

ASME B16.5 Studs (Flange Bolting Stud Bolts): Manufacturer & Exporter

Flange bolting is the set of studs and nuts that clamps two pipe flanges and their gasket together. ASME B16.5 fixes how many studs a flange takes, how thick they are and how long, for every pressure class and pipe size.

Exotic Alloy manufactures complete flange stud bolt sets in Mumbai, India, for refineries, pipelines, offshore and petrochemical plants, EPC contractors and shutdown teams. We supply across India and export to Angola, West Africa, the Gulf and the Caspian region.

The stud and its nuts

Flange studs are threaded from end to end, so the nuts can sit wherever the flange thickness puts them; the stud itself is covered on our full threaded studs page. Each stud takes two heavy hex nuts. For high-temperature joints with waisted studs see reduced shank studs.

ASME B16.5 Class 150–2500 RF & RTJ B7 + 2H PTFE coated
Flange bolting at a glance
Flanges
ASME B16.5, Class 150–2500, NPS 1/2–24
Stud
Full thread, ASME B18.31.2 flange bolting stud
Length
First thread to first thread, points excluded
Thread
UNC to 1 in, 8UN from 1-1/8 in
Nuts
2 heavy hex per stud, ASME B18.2.2
Grades
A193 B7 / A194 2H; B7M, L7, B8M
Related
Full threaded, double end, nuts
ASME B16.5 stud bolt set for a Class 600 NPS 8 raised face flange, drawn to scale: a 1-1/8-8UN full-thread stud, length L 7-1/2 inches measured from first full thread to first full thread with the chamfered points of up to 2 pitches outside L, and two heavy hex nuts 1-13/16 inches across flats and 1-7/64 inches high; 12 such sets per joint L = 7-1/2 in (190.5 mm), first full thread to first full thread point point points (1 to 2 pitches) are not included in L heavy hex nut heavy hex nut Flange Class 600, NPS 8, RF Per joint 12 studs, 24 nuts Stud 1-1/8-8UN × 7-1/2 Nut 1-13/16 AF, 1-7/64 high ASME B16.5 stud bolt set, Class 600 NPS 8, to scale EXOTIC ALLOY
One of the 12 stud bolt sets of a Class 600 NPS 8 raised face joint, to scale. The 7-1/2 in length runs from first full thread to first full thread; the points are extra.
Specification

Flange Stud Bolt Specification

The range we manufacture and supply.

Flange standardASME B16.5, Class 150, 300, 600, 900, 1500, 2500
Pipe sizesNPS 1/2 to 24 (Class 2500 to NPS 12)
StudsASME B18.31.2 flange bolting studs, 1/2 to 3-1/2 in
LengthB16.5 RF or RTJ lengths, or to your joint
ThreadUNC to 1 in, 8UN from 1-1/8 in, class 2A
NutsHeavy hex, ASME B18.2.2; A194 2H, 2HM, 7, 8, 8M
Stud gradesASTM A193 B7, B7M, B16, B8, B8M; A320 L7, L43
CoatingsPlain, zinc plated, hot-dip galvanized, PTFE (fluoropolymer)
CertificationEN 10204 3.1; 3.2 on request; NACE MR0175 for B7M / 2HM
SupplySets packed per joint, tagged by line or flange
Stud sizes

Stud Size by Flange Class & Pipe Size

Higher class and larger pipe, thicker studs.

Stud diameter in inches for every ASME B16.5 class and pipe size, as a grid: darker cells are thicker studs, from 1/2 inch for small Class 150 flanges to 3-1/2 inches for NPS 24 Class 1500; empty cells are sizes not listed in that class Stud diameter (in) by class and NPS, ASME B16.5 1/2 3/4 1 1¼ 1½ 2 2½ 3 3½ 4 5 6 8 10 12 14 16 18 20 24 Class 150 Class 150 NPS 1/2: 4 studs 1/2 in, RF length 2-1/4 in 1/2 Class 150 NPS 3/4: 4 studs 1/2 in, RF length 2-1/2 in 1/2 Class 150 NPS 1: 4 studs 1/2 in, RF length 2-1/2 in 1/2 Class 150 NPS 1-1/4: 4 studs 1/2 in, RF length 2-3/4 in 1/2 Class 150 NPS 1-1/2: 4 studs 1/2 in, RF length 2-3/4 in 1/2 Class 150 NPS 2: 4 studs 5/8 in, RF length 3-1/4 in 5/8 Class 150 NPS 2-1/2: 4 studs 5/8 in, RF length 3-1/2 in 5/8 Class 150 NPS 3: 4 studs 5/8 in, RF length 3-1/2 in 5/8 Class 150 NPS 3-1/2: 8 studs 5/8 in, RF length 3-1/2 in 5/8 Class 150 NPS 4: 8 studs 5/8 in, RF length 3-1/2 in 5/8 Class 150 NPS 5: 8 studs 3/4 in, RF length 3-3/4 in 3/4 Class 150 NPS 6: 8 studs 3/4 in, RF length 4 in 3/4 Class 150 NPS 8: 8 studs 3/4 in, RF length 4-1/4 in 3/4 Class 150 NPS 10: 12 studs 7/8 in, RF length 4-1/2 in 7/8 Class 150 NPS 12: 12 studs 7/8 in, RF length 4-3/4 in 7/8 Class 150 NPS 14: 12 studs 1 in, RF length 5-1/4 in 1 Class 150 NPS 16: 16 studs 1 in, RF length 5-1/4 in 1 Class 150 NPS 18: 16 studs 1-1/8 in, RF length 5-3/4 in 1 1/8 Class 150 NPS 20: 20 studs 1-1/8 in, RF length 6-1/4 in 1 1/8 Class 150 NPS 24: 20 studs 1-1/4 in, RF length 6-3/4 in 1 1/4 Class 300 Class 300 NPS 1/2: 4 studs 1/2 in, RF length 2-1/2 in 1/2 Class 300 NPS 3/4: 4 studs 5/8 in, RF length 3 in 5/8 Class 300 NPS 1: 4 studs 5/8 in, RF length 3 in 5/8 Class 300 NPS 1-1/4: 4 studs 5/8 in, RF length 3-1/4 in 5/8 Class 300 NPS 1-1/2: 4 studs 3/4 in, RF length 3-1/2 in 3/4 Class 300 NPS 2: 8 studs 5/8 in, RF length 3-1/2 in 5/8 Class 300 NPS 2-1/2: 8 studs 3/4 in, RF length 4 in 3/4 Class 300 NPS 3: 8 studs 3/4 in, RF length 4-1/4 in 3/4 Class 300 NPS 3-1/2: 8 studs 3/4 in, RF length 4-1/4 in 3/4 Class 300 NPS 4: 8 studs 3/4 in, RF length 4-1/2 in 3/4 Class 300 NPS 5: 8 studs 3/4 in, RF length 4-3/4 in 3/4 Class 300 NPS 6: 12 studs 3/4 in, RF length 4-3/4 in 3/4 Class 300 NPS 8: 12 studs 7/8 in, RF length 5-1/2 in 7/8 Class 300 NPS 10: 16 studs 1 in, RF length 6-1/4 in 1 Class 300 NPS 12: 16 studs 1-1/8 in, RF length 6-3/4 in 1 1/8 Class 300 NPS 14: 20 studs 1-1/8 in, RF length 7 in 1 1/8 Class 300 NPS 16: 20 studs 1-1/4 in, RF length 7-1/2 in 1 1/4 Class 300 NPS 18: 24 studs 1-1/4 in, RF length 7-3/4 in 1 1/4 Class 300 NPS 20: 24 studs 1-1/4 in, RF length 8 in 1 1/4 Class 300 NPS 24: 24 studs 1-1/2 in, RF length 9 in 1 1/2 Class 600 Class 600 NPS 1/2: 4 studs 1/2 in, RF length 3 in 1/2 Class 600 NPS 3/4: 4 studs 5/8 in, RF length 3-1/2 in 5/8 Class 600 NPS 1: 4 studs 5/8 in, RF length 3-1/2 in 5/8 Class 600 NPS 1-1/4: 4 studs 5/8 in, RF length 3-3/4 in 5/8 Class 600 NPS 1-1/2: 4 studs 3/4 in, RF length 4-1/4 in 3/4 Class 600 NPS 2: 8 studs 5/8 in, RF length 4-1/4 in 5/8 Class 600 NPS 2-1/2: 8 studs 3/4 in, RF length 4-3/4 in 3/4 Class 600 NPS 3: 8 studs 3/4 in, RF length 5 in 3/4 Class 600 NPS 3-1/2: 8 studs 7/8 in, RF length 5-1/2 in 7/8 Class 600 NPS 4: 8 studs 7/8 in, RF length 5-3/4 in 7/8 Class 600 NPS 5: 8 studs 1 in, RF length 6-1/2 in 1 Class 600 NPS 6: 12 studs 1 in, RF length 6-3/4 in 1 Class 600 NPS 8: 12 studs 1-1/8 in, RF length 7-1/2 in 1 1/8 Class 600 NPS 10: 16 studs 1-1/4 in, RF length 8-1/2 in 1 1/4 Class 600 NPS 12: 20 studs 1-1/4 in, RF length 8-3/4 in 1 1/4 Class 600 NPS 14: 20 studs 1-3/8 in, RF length 9-1/4 in 1 3/8 Class 600 NPS 16: 20 studs 1-1/2 in, RF length 10 in 1 1/2 Class 600 NPS 18: 20 studs 1-5/8 in, RF length 10-3/4 in 1 5/8 Class 600 NPS 20: 24 studs 1-5/8 in, RF length 11-1/4 in 1 5/8 Class 600 NPS 24: 24 studs 1-7/8 in, RF length 13 in 1 7/8 Class 900 Class 900 NPS 1/2: 4 studs 3/4 in, RF length 4-1/4 in 3/4 Class 900 NPS 3/4: 4 studs 3/4 in, RF length 4-1/2 in 3/4 Class 900 NPS 1: 4 studs 7/8 in, RF length 5 in 7/8 Class 900 NPS 1-1/4: 4 studs 7/8 in, RF length 5 in 7/8 Class 900 NPS 1-1/2: 4 studs 1 in, RF length 5-1/2 in 1 Class 900 NPS 2: 8 studs 7/8 in, RF length 5-3/4 in 7/8 Class 900 NPS 2-1/2: 8 studs 1 in, RF length 6-1/4 in 1 Class 900 NPS 3: 8 studs 7/8 in, RF length 5-3/4 in 7/8 Class 900 NPS 4: 8 studs 1-1/8 in, RF length 6-3/4 in 1 1/8 Class 900 NPS 5: 8 studs 1-1/4 in, RF length 7-1/2 in 1 1/4 Class 900 NPS 6: 12 studs 1-1/8 in, RF length 7-1/2 in 1 1/8 Class 900 NPS 8: 12 studs 1-3/8 in, RF length 8-3/4 in 1 3/8 Class 900 NPS 10: 16 studs 1-3/8 in, RF length 9-1/4 in 1 3/8 Class 900 NPS 12: 20 studs 1-3/8 in, RF length 10 in 1 3/8 Class 900 NPS 14: 20 studs 1-1/2 in, RF length 10-3/4 in 1 1/2 Class 900 NPS 16: 20 studs 1-5/8 in, RF length 11-1/4 in 1 5/8 Class 900 NPS 18: 20 studs 1-7/8 in, RF length 12-3/4 in 1 7/8 Class 900 NPS 20: 20 studs 2 in, RF length 13-3/4 in 2 Class 900 NPS 24: 20 studs 2-1/2 in, RF length 17-1/4 in 2 1/2 Class 1500 Class 1500 NPS 1/2: 4 studs 3/4 in, RF length 4-1/4 in 3/4 Class 1500 NPS 3/4: 4 studs 3/4 in, RF length 4-1/2 in 3/4 Class 1500 NPS 1: 4 studs 7/8 in, RF length 5 in 7/8 Class 1500 NPS 1-1/4: 4 studs 7/8 in, RF length 5 in 7/8 Class 1500 NPS 1-1/2: 4 studs 1 in, RF length 5-1/2 in 1 Class 1500 NPS 2: 8 studs 7/8 in, RF length 5-3/4 in 7/8 Class 1500 NPS 2-1/2: 8 studs 1 in, RF length 6-1/4 in 1 Class 1500 NPS 3: 8 studs 1-1/8 in, RF length 7 in 1 1/8 Class 1500 NPS 4: 8 studs 1-1/4 in, RF length 7-3/4 in 1 1/4 Class 1500 NPS 5: 8 studs 1-1/2 in, RF length 9-3/4 in 1 1/2 Class 1500 NPS 6: 12 studs 1-3/8 in, RF length 10-1/4 in 1 3/8 Class 1500 NPS 8: 12 studs 1-5/8 in, RF length 11-1/2 in 1 5/8 Class 1500 NPS 10: 12 studs 1-7/8 in, RF length 13-1/4 in 1 7/8 Class 1500 NPS 12: 16 studs 2 in, RF length 14-3/4 in 2 Class 1500 NPS 14: 16 studs 2-1/4 in, RF length 16 in 2 1/4 Class 1500 NPS 16: 16 studs 2-1/2 in, RF length 17-1/2 in 2 1/2 Class 1500 NPS 18: 16 studs 2-3/4 in, RF length 19-1/2 in 2 3/4 Class 1500 NPS 20: 16 studs 3 in, RF length 21-1/4 in 3 Class 1500 NPS 24: 16 studs 3-1/2 in, RF length 24-1/4 in 3 1/2 Class 2500 Class 2500 NPS 1/2: 4 studs 3/4 in, RF length 4-3/4 in 3/4 Class 2500 NPS 3/4: 4 studs 3/4 in, RF length 5 in 3/4 Class 2500 NPS 1: 4 studs 7/8 in, RF length 5-1/2 in 7/8 Class 2500 NPS 1-1/4: 4 studs 1 in, RF length 6 in 1 Class 2500 NPS 1-1/2: 4 studs 1-1/8 in, RF length 6-3/4 in 1 1/8 Class 2500 NPS 2: 8 studs 1 in, RF length 7 in 1 Class 2500 NPS 2-1/2: 8 studs 1-1/8 in, RF length 7-3/4 in 1 1/8 Class 2500 NPS 3: 8 studs 1-1/4 in, RF length 8-3/4 in 1 1/4 Class 2500 NPS 4: 8 studs 1-1/2 in, RF length 10 in 1 1/2 Class 2500 NPS 5: 8 studs 1-3/4 in, RF length 11-3/4 in 1 3/4 Class 2500 NPS 6: 8 studs 2 in, RF length 13-1/2 in 2 Class 2500 NPS 8: 12 studs 2 in, RF length 15 in 2 Class 2500 NPS 10: 12 studs 2-1/2 in, RF length 19-1/4 in 2 1/2 Class 2500 NPS 12: 12 studs 2-3/4 in, RF length 21-1/4 in 2 3/4 thinner thicker stud NPS across the top; empty = not listed EXOTIC ALLOY
The whole ASME B16.5 range on one grid. Stud diameters run from 1/2 in to 3-1/2 in; hover a cell for the number of studs and the RF length.

Class 900 and 1500 have no NPS 3-1/2; Class 2500 ends at NPS 12. Diameters do not always rise with size: Class 900 NPS 3 uses 7/8 in studs, NPS 2-1/2 uses 1 in.

Stud charts

ASME B16.5 Stud Bolt Charts, Class 150 to 2500

NPSStudsStud sizeLength RF
in (mm)		Length RTJ
in (mm)		Heavy hex nut
across flats / height, in
1/241/2-13 UNC2-1/4 (57)–7/8 / 31/64
3/441/2-13 UNC2-1/2 (64)–7/8 / 31/64
141/2-13 UNC2-1/2 (64)3 (76)7/8 / 31/64
1-1/441/2-13 UNC2-3/4 (70)3-1/4 (83)7/8 / 31/64
1-1/241/2-13 UNC2-3/4 (70)3-1/4 (83)7/8 / 31/64
245/8-11 UNC3-1/4 (83)3-3/4 (95)1-1/16 / 39/64
2-1/245/8-11 UNC3-1/2 (89)4 (102)1-1/16 / 39/64
345/8-11 UNC3-1/2 (89)4 (102)1-1/16 / 39/64
3-1/285/8-11 UNC3-1/2 (89)4 (102)1-1/16 / 39/64
485/8-11 UNC3-1/2 (89)4 (102)1-1/16 / 39/64
583/4-10 UNC3-3/4 (95)4-1/4 (108)1-1/4 / 47/64
683/4-10 UNC4 (102)4-1/2 (114)1-1/4 / 47/64
883/4-10 UNC4-1/4 (108)4-3/4 (121)1-1/4 / 47/64
10127/8-9 UNC4-1/2 (114)5 (127)1-7/16 / 55/64
12127/8-9 UNC4-3/4 (121)5-1/4 (133)1-7/16 / 55/64
14121-8 UNC5-1/4 (133)5-3/4 (146)1-5/8 / 63/64
16161-8 UNC5-1/4 (133)5-3/4 (146)1-5/8 / 63/64
18161-1/8-8 UN5-3/4 (146)6-1/4 (159)1-13/16 / 1-7/64
20201-1/8-8 UN6-1/4 (159)6-3/4 (171)1-13/16 / 1-7/64
24201-1/4-8 UN6-3/4 (171)7-1/4 (184)2 / 1-7/32
NPSStudsStud sizeLength RF
in (mm)		Length RTJ
in (mm)		Heavy hex nut
across flats / height, in
1/241/2-13 UNC2-1/2 (64)3 (76)7/8 / 31/64
3/445/8-11 UNC3 (76)3-1/2 (89)1-1/16 / 39/64
145/8-11 UNC3 (76)3-1/2 (89)1-1/16 / 39/64
1-1/445/8-11 UNC3-1/4 (83)3-3/4 (95)1-1/16 / 39/64
1-1/243/4-10 UNC3-1/2 (89)4 (102)1-1/4 / 47/64
285/8-11 UNC3-1/2 (89)4 (102)1-1/16 / 39/64
2-1/283/4-10 UNC4 (102)4-1/2 (114)1-1/4 / 47/64
383/4-10 UNC4-1/4 (108)4-3/4 (121)1-1/4 / 47/64
3-1/283/4-10 UNC4-1/4 (108)5 (127)1-1/4 / 47/64
483/4-10 UNC4-1/2 (114)5 (127)1-1/4 / 47/64
583/4-10 UNC4-3/4 (121)5-1/4 (133)1-1/4 / 47/64
6123/4-10 UNC4-3/4 (121)5-1/2 (140)1-1/4 / 47/64
8127/8-9 UNC5-1/2 (140)6 (152)1-7/16 / 55/64
10161-8 UNC6-1/4 (159)6-3/4 (171)1-5/8 / 63/64
12161-1/8-8 UN6-3/4 (171)7-1/4 (184)1-13/16 / 1-7/64
14201-1/8-8 UN7 (178)7-1/2 (190)1-13/16 / 1-7/64
16201-1/4-8 UN7-1/2 (190)8 (203)2 / 1-7/32
18241-1/4-8 UN7-3/4 (197)8-1/4 (210)2 / 1-7/32
20241-1/4-8 UN8 (203)8-3/4 (222)2 / 1-7/32
24241-1/2-8 UN9 (229)10 (254)2-3/8 / 1-15/32
NPSStudsStud sizeLength RF
in (mm)		Length RTJ
in (mm)		Heavy hex nut
across flats / height, in
1/241/2-13 UNC3 (76)3 (76)7/8 / 31/64
3/445/8-11 UNC3-1/2 (89)3-1/2 (89)1-1/16 / 39/64
145/8-11 UNC3-1/2 (89)3-1/2 (89)1-1/16 / 39/64
1-1/445/8-11 UNC3-3/4 (95)3-3/4 (95)1-1/16 / 39/64
1-1/243/4-10 UNC4-1/4 (108)4-1/4 (108)1-1/4 / 47/64
285/8-11 UNC4-1/4 (108)4-1/4 (108)1-1/16 / 39/64
2-1/283/4-10 UNC4-3/4 (121)4-3/4 (121)1-1/4 / 47/64
383/4-10 UNC5 (127)5 (127)1-1/4 / 47/64
3-1/287/8-9 UNC5-1/2 (140)5-1/2 (140)1-7/16 / 55/64
487/8-9 UNC5-3/4 (146)5-3/4 (146)1-7/16 / 55/64
581-8 UNC6-1/2 (165)6-1/2 (165)1-5/8 / 63/64
6121-8 UNC6-3/4 (171)6-3/4 (171)1-5/8 / 63/64
8121-1/8-8 UN7-1/2 (190)7-3/4 (197)1-13/16 / 1-7/64
10161-1/4-8 UN8-1/2 (216)8-1/2 (216)2 / 1-7/32
12201-1/4-8 UN8-3/4 (222)8-3/4 (222)2 / 1-7/32
14201-3/8-8 UN9-1/4 (235)9-1/4 (235)2-3/16 / 1-11/32
16201-1/2-8 UN10 (254)10 (254)2-3/8 / 1-15/32
18201-5/8-8 UN10-3/4 (273)10-3/4 (273)2-9/16 / 1-19/32
20241-5/8-8 UN11-1/4 (286)11-1/2 (292)2-9/16 / 1-19/32
24241-7/8-8 UN13 (330)13-1/4 (337)2-15/16 / 1-27/32
NPSStudsStud sizeLength RF
in (mm)		Length RTJ
in (mm)		Heavy hex nut
across flats / height, in
1/243/4-10 UNC4-1/4 (108)4-1/4 (108)1-1/4 / 47/64
3/443/4-10 UNC4-1/2 (114)4-1/2 (114)1-1/4 / 47/64
147/8-9 UNC5 (127)5 (127)1-7/16 / 55/64
1-1/447/8-9 UNC5 (127)5 (127)1-7/16 / 55/64
1-1/241-8 UNC5-1/2 (140)5-1/2 (140)1-5/8 / 63/64
287/8-9 UNC5-3/4 (146)5-3/4 (146)1-7/16 / 55/64
2-1/281-8 UNC6-1/4 (159)6-1/4 (159)1-5/8 / 63/64
387/8-9 UNC5-3/4 (146)5-3/4 (146)1-7/16 / 55/64
481-1/8-8 UN6-3/4 (171)6-3/4 (171)1-13/16 / 1-7/64
581-1/4-8 UN7-1/2 (190)7-1/2 (190)2 / 1-7/32
6121-1/8-8 UN7-1/2 (190)7-3/4 (197)1-13/16 / 1-7/64
8121-3/8-8 UN8-3/4 (222)8-3/4 (222)2-3/16 / 1-11/32
10161-3/8-8 UN9-1/4 (235)9-1/4 (235)2-3/16 / 1-11/32
12201-3/8-8 UN10 (254)10 (254)2-3/16 / 1-11/32
14201-1/2-8 UN10-3/4 (273)11 (279)2-3/8 / 1-15/32
16201-5/8-8 UN11-1/4 (286)11-1/2 (292)2-9/16 / 1-19/32
18201-7/8-8 UN12-3/4 (324)13-1/4 (337)2-15/16 / 1-27/32
20202-8 UN13-3/4 (349)14-1/4 (362)3-1/8 / 1-31/32
24202-1/2-8 UN17-1/4 (438)18 (457)3-7/8 / 2-29/64
NPSStudsStud sizeLength RF
in (mm)		Length RTJ
in (mm)		Heavy hex nut
across flats / height, in
1/243/4-10 UNC4-1/4 (108)4-1/4 (108)1-1/4 / 47/64
3/443/4-10 UNC4-1/2 (114)4-1/2 (114)1-1/4 / 47/64
147/8-9 UNC5 (127)5 (127)1-7/16 / 55/64
1-1/447/8-9 UNC5 (127)5 (127)1-7/16 / 55/64
1-1/241-8 UNC5-1/2 (140)5-1/2 (140)1-5/8 / 63/64
287/8-9 UNC5-3/4 (146)5-3/4 (146)1-7/16 / 55/64
2-1/281-8 UNC6-1/4 (159)6-1/4 (159)1-5/8 / 63/64
381-1/8-8 UN7 (178)7 (178)1-13/16 / 1-7/64
481-1/4-8 UN7-3/4 (197)7-3/4 (197)2 / 1-7/32
581-1/2-8 UN9-3/4 (248)9-3/4 (248)2-3/8 / 1-15/32
6121-3/8-8 UN10-1/4 (260)10-1/2 (267)2-3/16 / 1-11/32
8121-5/8-8 UN11-1/2 (292)11-3/4 or 12-3/4*2-9/16 / 1-19/32
10121-7/8-8 UN13-1/4 (337)13-1/2 (343)2-15/16 / 1-27/32
12162-8 UN14-3/4 (375)15-1/4 (387)3-1/8 / 1-31/32
14162-1/4-8 UN16 (406)16-3/4 (425)3-1/2 / 2-13/64
16162-1/2-8 UN17-1/2 (444)18-1/2 (470)3-7/8 / 2-29/64
18162-3/4-8 UN19-1/2 (495)20-3/4 (527)4-1/4 / 2-45/64
20163-8 UN21-1/4 (540)22-1/4 (565)4-5/8 / 2-61/64
24163-1/2-8 UN24-1/4 (616)25-1/2 (648)5-3/8 / 3-7/16
NPSStudsStud sizeLength RF
in (mm)		Length RTJ
in (mm)		Heavy hex nut
across flats / height, in
1/243/4-10 UNC4-3/4 (121)4-3/4 (121)1-1/4 / 47/64
3/443/4-10 UNC5 (127)5 (127)1-1/4 / 47/64
147/8-9 UNC5-1/2 (140)5-1/2 (140)1-7/16 / 55/64
1-1/441-8 UNC6 (152)6 (152)1-5/8 / 63/64
1-1/241-1/8-8 UN6-3/4 (171)6-3/4 (171)1-13/16 / 1-7/64
281-8 UNC7 (178)7 (178)1-5/8 / 63/64
2-1/281-1/8-8 UN7-3/4 (197)8 (203)1-13/16 / 1-7/64
381-1/4-8 UN8-3/4 (222)9 (229)2 / 1-7/32
481-1/2-8 UN10 (254)10-1/4 (260)2-3/8 / 1-15/32
581-3/4-8 UN11-3/4 (298)12-1/4 (311)2-3/4 / 1-23/32
682-8 UN13-1/2 (343)14 (356)3-1/8 / 1-31/32
8122-8 UN15 (381)15-1/2 (394)3-1/8 / 1-31/32
10122-1/2-8 UN19-1/4 (489)20 (508)3-7/8 / 2-29/64
12122-3/4-8 UN21-1/4 (540)22 (559)4-1/4 / 2-45/64

Number, size and length of studs for ASME B16.5 flanges, inch; mm rounded. Length L from first full thread to first full thread. RF lengths for the class’s raised face (0.06 in for Class 150 and 300, 0.25 in above). Class 150 NPS 1/2 and 3/4 have no ring joint. *Class 1500 NPS 8 RTJ: the published charts we compared give 11-3/4 in and 12-3/4 in; we confirm it against your flange before cutting. Nut sizes from ASME B18.2.2.

RF & RTJ

Raised Face or Ring Joint: Why the Length Changes

Raised face and ring type joint flanges compared for Class 300 NPS 4, studs drawn to scale: 8 studs 3/4-10 UNC per joint, 4-1/2 inches long for the raised face joint with a flat gasket, 5 inches long for the ring joint, where the ring keeps the flange faces apart; flanges schematic gasket L = 4-1/2 in Raised face (RF) ring L = 5 in Ring type joint (RTJ) Class 300 NPS 4: 8 studs 3/4-10 UNC; stud and nuts to scale, flanges schematic EXOTIC ALLOY
The same flange size, two joint types. The ring holds the flange faces apart, so the RTJ stud is 1/2 in longer here.
  • RF: flat gasket on the raised faces; shortest studs.
  • RTJ: metal ring in grooves; flanges stand apart, studs often longer.
  • Class 600 and up: with the 0.25 in raised face, RF and RTJ lengths are often the same.
  • Measuring: L excludes the points; order by L, not overall length.
Stud length LTolerance
up to 12 in±1/16 in (±1.6 mm)
over 12 to 18 in±1/8 in (±3.2 mm)
over 18 in±1/4 in (±6.4 mm)

Length tolerance for flange bolting studs (ASME B18.31.2).

On the flange

Studs on the Flange Face

Face of a Class 600 NPS 8 flange to scale: outside diameter 16-1/2 inches, 12 bolt holes of 1-1/4 inch on a 13-3/4 inch bolt circle, holes straddling the centre lines, each taking a 1-1/8 inch stud bolt hole 1: 1-1/4 in hole, 1-1/8 in stud bolt hole 2: 1-1/4 in hole, 1-1/8 in stud bolt hole 3: 1-1/4 in hole, 1-1/8 in stud bolt hole 4: 1-1/4 in hole, 1-1/8 in stud bolt hole 5: 1-1/4 in hole, 1-1/8 in stud bolt hole 6: 1-1/4 in hole, 1-1/8 in stud bolt hole 7: 1-1/4 in hole, 1-1/8 in stud bolt hole 8: 1-1/4 in hole, 1-1/8 in stud bolt hole 9: 1-1/4 in hole, 1-1/8 in stud bolt hole 10: 1-1/4 in hole, 1-1/8 in stud bolt hole 11: 1-1/4 in hole, 1-1/8 in stud bolt hole 12: 1-1/4 in hole, 1-1/8 in stud bolt circle 13-3/4 OD 16-1/2 Class 600 NPS 8 flange face, to scale: 12 holes 1-1/4 in for 1-1/8 in studs Holes straddle the centre lines; tighten in a cross (star) pattern, as in ASME PCC-1. EXOTIC ALLOY
Class 600 NPS 8: 12 studs on a 13-3/4 in bolt circle. Each 1-1/4 in hole is 1/8 in larger than its 1-1/8 in stud.

Before the joint is made up

  • Check the stud size, length and grade marking against the line list.
  • Run each nut along its stud by hand; lubricate threads and nut faces.
  • Leave a little thread showing beyond each nut.

Tightening

  • Bring the flanges together evenly with all studs snug.
  • Tighten in a cross (star) pattern in several passes.
  • Follow the procedure of ASME PCC-1 or your company standard.
Finder

Flange Bolting Finder: Studs & Nuts per Joint

Pick the flange; get the stud set, the quantities and the load.

Flange & order

Stud number, size and length from the ASME B16.5 charts on this page; nuts ASME B18.2.2 heavy hex, two per stud. Spares are rounded up per item. Our calculation: minimum yield load = stress area × ASTM minimum yield strength (A193 / A320, by diameter); mass of a stud ≈ pitch-diameter cylinder over L plus two pitches, steel, nuts not included.

Result
12
studs per joint, 1-1/8 in
7-1/2
in stud length L (191 mm)
Thread:1-1/8-8UN
Studs / nuts to order:12 / 24
Nut across flats / height:1-13/16 / 1-7/64 in
Length tolerance:±1/16 in
Min. yield load, stud / joint:83.0 / 996 kip
Studs mass (approx.):1.9 lb each, 23 lb
Designation:12 × stud 1-1/8-8UN × 7-1/2 in, ASTM A193 B7, with 24 heavy hex nuts A194 2H

Grades

Stud & Nut Grade Combinations

StudsNutsWhere
ASTM A193 B7A194 2HCarbon and low-alloy steel flanges, the standard set
ASTM A193 B7MA194 2HMSour service, hardness limited
ASTM A193 B16A194 7Higher-temperature joints (A194 grade 4 was dropped from ASTM A194 in 2017)
ASTM A320 L7A194 7Low-temperature service
ASTM A193 B8 / B8M (Class 1 or 2)A194 8 / 8MStainless flanges, cryogenic and corrosive service
Duplex, super duplex, nickel alloysSame alloySeawater, sour and high-temperature lines

Common stud and nut pairings; follow your piping specification. Strength of each grade on our full threaded studs page.

Alloy steel
B7 · B7M · L7

Most flange bolting.

41404340
Stainless
B8 · B8M

As in the photo.

304316
Special alloys
S32760 · 718 · 625

Offshore and sour lines.

S32760718625
Manufacturing

How Our Flange Stud Bolt Sets Are Made

1

Bar

Heat-treated bar to A193 / A320, certified by heat.

2

Cut

Cut to the B16.5 length plus points.

3

Thread

Rolled end to end, UNC or 8UN, chamfered.

4

Nuts

Heavy hex nuts to A194, gauged on the studs.

5

Coat

Plain, zinc, galvanized or PTFE coated.

6

Pack

Sets assembled and packed per joint.

Applications

Where Our Flange Stud Bolts Are Used

Refineries

Process piping and exchanger connections.

Oil & gas

Wellhead piping, manifolds and pipelines.

Offshore

Coated and duplex sets for seawater exposure.

Petrochemical

Reactor and column nozzles.

Power plants

Steam and feedwater lines.

LNG & cryogenic

L7 and B8 sets for cold service.

Quality & testing

Flange Bolting Inspection & Certification

CheckMethodApplied to
Stud threadGO / NOT GO ring gauges, 2AEvery lot
Nut threadGO / NOT GO plug gaugesEvery lot
Length LFirst thread to first threadEvery lot
Hardness, tensileTo ASTM A193 / A320 / A194Every heat-treat lot
ImpactCharpy V at test temperatureA320 grades
CoatingThickness gaugeCoated sets

Every shipment includes

  • EN 10204 3.1 certificates for studs and nuts
  • Grade marking on studs and nuts
  • Packing list by joint or line

On request

  • EN 10204 3.2 with third-party inspection
  • NACE MR0175 / ISO 15156 compliance
  • Coating and PMI reports
FAQ

Flange Bolting Questions, Answered

ASME B16.5 sets the number and size of the studs for every class and pipe size. A Class 150 NPS 4 flange takes 8 studs of 5/8 in, a Class 600 NPS 8 flange 12 studs of 1-1/8 in and a Class 1500 NPS 24 flange 16 studs of 3-1/2 in.

From first full thread to first full thread, without the chamfered points, which are one to two pitches long at each end. The tolerance is plus or minus 1/16 in up to 12 in long, 1/8 in up to 18 in and 1/4 in above.

In a ring type joint a metal ring sits in grooves in both flanges and keeps the flange faces apart, so the joint is thicker. For Class 300 NPS 4 the studs are 4-1/2 in long for a raised face flange and 5 in for a ring type joint.

On the raised face of the class: 0.06 in (2 mm) for Class 150 and 300, 0.25 in (7 mm) for Class 600 and above. With the taller raised face, many Class 600 to 2500 sizes use the same stud length for RF and RTJ.

UNC up to 1 in and the 8-thread series 8UN from 1-1/8 in, class 2A, with two heavy hex nuts to ASME B18.2.2 on each stud. A 1-1/8 in stud takes nuts 1-13/16 in across flats.

ASTM A193 B7 studs with A194 2H heavy hex nuts are the usual set for carbon-steel flanges. Common alternatives are B7M with 2HM nuts for sour service, A320 L7 with A194 Grade 7 nuts for low temperatures, and B8 or B8M with A194 8 or 8M nuts for stainless flanges.

Two heavy hex nuts per stud, so a Class 600 NPS 8 joint with 12 studs needs 24 nuts. Our finder counts studs and nuts for any number of joints.

We supply studs and nuts plain, zinc plated, hot-dip galvanized or with a fluoropolymer (PTFE) coating, which protects against corrosion and makes the nuts easier to remove.
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