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ASME B18.31.2 · DIN 976-1 · 1/4–4 in, M2–M72

Full Threaded Studs Manufacturer in India

Threaded from end to end, so a nut can sit anywhere along them. We make full threaded studs to ASME B18.31.2 (continuous thread and flange bolting studs, UNC, UNF and 8UN) and DIN 976-1 (Form A and B), in A193 B7, B8M, A320 L7, classes 8.8 to 12.9, stainless and nickel alloys. Below: how length is measured, full dimension and tolerance tables, grades, loads and a stud length finder.

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  • ISO 9001:2015 certified manufacturer
  • Cut, chamfered & rolled to length
  • Inch and metric
  • EN 10204 3.1 / 3.2
Stainless steel full threaded studs
Inch 1/4 – 4 in Metric M2 – M72 Thread UNC, 8UN, ISO
Overview

ASME B18.31.2 & DIN 976-1 Studs (Full Threaded Studs): Manufacturer & Distributor

A full threaded stud is a headless rod threaded from end to end. Two nuts clamp the joint, or one end goes into a tapped hole; because the thread runs the whole length, the nuts can sit anywhere along it.

Exotic Alloy manufactures full threaded studs in Mumbai, India, and keeps common sizes and grades in stock for refineries, pipeline and process plants, fabricators and machine builders. We supply across India and export to Kazakhstan, Central Asia, the Gulf and Africa.

Stud, stud bolt or threaded rod?

All three are threaded right through. ASME B18.31.2 calls the inch part a continuous thread stud; for pipe flanges the same kind of part is a flange bolting stud (“stud bolt”) and its length is measured differently (section 03). Metric studs follow DIN 976-1, which also lists 1, 2 and 3 m rods. For studs with a plain shank see double end, tap end and reduced shank studs; for complete flange sets see flange bolting.

ASME B18.31.2 DIN 976-1 A & B UNC / UNF / 8UN A193 B7 / B8M 8.8 / 10.9 / A4-70
Full threaded stud at a glance
Inch
ASME B18.31.2, 1/4 to 4 in
Metric
DIN 976-1 Form A / B, M2 to M72
Thread
UNC, UNF, 8UN; ISO coarse & fine, 6g
Ends
Chamfered, 1–2 pitches (ASME)
Length
Overall; flange studs between first full threads
Grades
A193 B7, B8M, A320 L7; 4.8–12.9, A2 / A4-70
Related
Flange bolting, double end, nuts
ASME B18.31.2 continuous thread stud 3/4-10 UNC by 5 inch drawn to scale: threaded over its full length, both ends chamfered, chamfered thread distance U of 0.100 to 0.200 inch (one to two pitches) at each end, overall length L T measured end to end with a tolerance of plus or minus 0.10 inch; end view showing the grade symbol B7 and the maker's mark stamped on one end LT = 5 in overall, end to end (±0.10 in) D U U U = 0.100–0.200 in (1 to 2 pitches): chamfer to first full thread first full thread P = 1/10 in (10 threads per inch, UNC) B7 EA End view (enlarged) grade + maker’s mark on one end (ASTM A193) ASME B18.31.2 continuous thread stud, 3/4-10 UNC × 5 in, to scale EXOTIC ALLOY
A 3/4-10 UNC × 5 in continuous thread stud to ASME B18.31.2, to scale. Both ends chamfered; U, the distance from the end to the first full thread, is 1 to 2 pitches. The grade and maker’s mark go on one end.
Specification

Full Threaded Stud Specification

The range we manufacture and supply.

Inch standardASME B18.31.2-2014 continuous thread stud and flange bolting stud
Metric standardDIN 976-1:2016 Form A (plain ends), Form B (chamfered)
Sizes1/4 to 4 in; M2 to M72
Lengths1/4 in steps to 10 in, 1/2 in above; DIN 5–500 mm, rods 1 / 2 / 3 m
ThreadUNC, UNF, 8UN; ISO metric coarse and fine, 6g
GradesASTM A193 B7, B7M, B16, B8, B8M; A320 L7, L43; 4.8–12.9; A2-70, A4-70
Special alloysInconel 718 (ASTM A1014), A-286 (A453 660), duplex, super duplex, Monel K-500
FinishPlain, zinc plated, hot-dip galvanized, PTFE (fluoropolymer) coated
CertificationEN 10204 3.1; 3.2 on request
SupplyStuds alone or with nuts and washers, bundled or boxed
Types & length

Continuous Thread Stud, Stud Bolt & DIN 976-1: How Length Is Measured

The studs look alike; the length on the order means different things.

How the length of a fully threaded stud is measured, four studs at the same scale: ASME B18.31.2 continuous thread stud 1/2-13 by 4 inch measured end to end as L T; ASME flange bolting stud 1/2-13 by 4 inch measured between the first full threads, so it is 0.15 to 0.31 inch longer overall; DIN 976-1 Form A M12 by 100 with plain ends and Form B with chamfered ends, both measured overall Continuous thread stud ASME B18.31.2 Flange bolting stud ASME B18.31.2 / B16.5 DIN 976-1 Form A plain ends DIN 976-1 Form B chamfered ends LT = 4 in, end to end 1/2-13 × 4 in overall 4 in ± 0.08 L = 4 in, first full thread to first full thread U U 1/2-13 × 4 in overall 4 in + 2U = 4.15–4.31 in l = 100 mm, overall M12 × 100 100 mm = 3.94 in l = 100 mm, overall M12 × 100 100 mm = 3.94 in Same scale throughout; dashed orange lines mark the first full thread. Chamfers drawn at U max (2 pitches). EXOTIC ALLOY
Four fully threaded studs at the same scale. A 4 in flange bolting stud is 0.15 to 0.31 in longer overall than a 4 in continuous thread stud, because its two chamfered ends lie outside L.
TypeStandardEndsLength measuredLength tolerance
Continuous thread studASME B18.31.2Chamfered, U = 1–2 pitchesLT, overall, end to end±0.04 to ±0.18 in
Flange bolting stud (stud bolt)ASME B18.31.2, for ASME B16.5 flangesChamfered, U = 1–2 pitchesL, first full thread to first full thread±0.062 to ±0.250 in
Stud, Form ADIN 976-1Plainl, overall–
Stud, Form BDIN 976-1Chamferedl, overall–
Threaded rod, 1 / 2 / 3 mDIN 976-1 (formerly DIN 975)CutRod length–

Tolerances by length band in section 04. On an order for inch studs, say whether the length is overall or first thread to first thread.

Dimensions

Full Threaded Stud Dimensions & Tolerances

SizeD
in		UNC
thr./in		UNF
thr./in		8UN
thr./in		U, UNC
min–max, in		U, UNF
min–max, in		U, 8UN
min–max, in
1/4 in0.25002028–.050–.100.036–.071–
5/16 in0.31251824–.056–.111.042–.083–
3/8 in0.37501624–.063–.125.042–.083–
7/16 in0.43751420–.072–.143.050–.100–
1/2 in0.50001320–.077–.154.050–.100–
9/16 in0.56251218–.084–.167.056–.111–
5/8 in0.62501118–.091–.182.056–.111–
3/4 in0.75001016–.100–.200.063–.125–
7/8 in0.8750914–.111–.222.072–.143–
1 in1.0000812–.125–.250.084–.167–
1-1/8 in1.12507128.143–.286.084–.167.125–.250
1-1/4 in1.25007128.143–.286.084–.167.125–.250
1-3/8 in1.37506128.167–.333.084–.167.125–.250
1-1/2 in1.50006128.167–.333.084–.167.125–.250
1-5/8 in1.6250––8––.125–.250
1-3/4 in1.75005–8.200–.400–.125–.250
1-7/8 in1.8750––8––.125–.250
2 in2.00004½–8.222–.444–.125–.250
2-1/4 in2.25004½–8.222–.444–.125–.250
2-1/2 in2.50004–8.250–.500–.125–.250
2-3/4 in2.75004–8.250–.500–.125–.250
3 in3.00004–8.250–.500–.125–.250
3-1/4 in3.25004–8.250–.500–.125–.250
3-1/2 in3.50004–8.250–.500–.125–.250
3-3/4 in3.75004–8.250–.500–.125–.250
4 in4.00004–8.250–.500–.125–.250

ASME B18.31.2-2014 Table 1, inch. U: chamfered thread distance from the end to the first full thread, checked with a NOT GO major-diameter ring gauge; 1 to 2 pitches at each end. Lengths in 1/4 in steps up to 10 in, 1/2 in steps above.

Continuous thread stud (overall LT)

LT lengthTolerance
in		Tolerance
mm
3/4 to 2-1/2 in±.040±1.02
over 2-1/2 to 4 in±.080±2.03
over 4 to 8 in±.100±2.54
over 8 to 16 in±.120±3.05
over 16 in±.180±4.57

Flange bolting stud (L between first full threads)

L lengthTolerance
in		Tolerance
mm
3/4 to 12 in±.062±1.57
over 12 to 18 in±.125±3.17
over 18 in±.250±6.35

ASME B18.31.2, inch; mm values converted.

SizePitch P
coarse, mm		Fine pitches
mm		Stress area As
mm²		Mass
kg per metre		Classes
DIN 976-1
M20.4–2.10.019by agreement
M2.50.45–3.40.03by agreement
M30.5–5.00.043*4.8–12.9, A2/A4-70
(M3.5)0.6–6.80.05984.8–12.9, A2/A4-70
M40.7–8.80.07764.8–12.9, A2/A4-70
M50.8–14.20.1244.8–12.9, A2/A4-70
M61–20.10.1774.8–12.9, A2/A4-70
M81.25136.60.3194.8–12.9, A2/A4-70
M101.51, 1.2558.00.5024.8–12.9, A2/A4-70
M121.751.25, 1.584.30.7284.8–12.9, A2/A4-70
(M14)21.51150.9954.8–12.9, A2/A4-70
M1621.51571.334.8–12.9, A2/A4-70
(M18)2.51.51921.654.8–12.9, A2/A4-70
M202.51.52452.084.8–12.9, A2/A4-70
(M22)2.51.53032.564.8–12.9, A2/A4-70
M243235334.8–12.9, A2/A4-70
(M27)324593.8824.8–12.9
M303.525614.7444.8–12.9
(M33)3.526945.8124.8–12.9
M36438176.8884.8–12.9
(M39)439768.1644.8–12.9
M424.5311219.412by agreement
(M45)4.53130610.914by agreement
M4853147312.348by agreement
(M52)53175814.654by agreement
M565.54203016.946by agreement
(M60)5.54236219.632by agreement
M6464267622.272by agreement
(M68)64305525.334by agreement
M72–6346028.596by agreement

DIN 976-1:2016, mm; sizes in brackets are second choice. Stress area As by the ISO 898-1 formula (our calculation); mass per metre of steel stud from DIN 976-1. *M3: the pitch-diameter formula that reproduces every other row within 2 % gives 0.044 kg. M72 is listed with a 6 mm pitch only. Lengths 5–500 mm (14, 18, 22, 28, 85 and 95 mm second choice) and rods of 1, 2 and 3 m; thread tolerance 6g. Larger sizes and other classes by agreement.

Inch heavy hex nuts, ASME B18.2.2

SizeAcross flats s
max, in		Height m
nominal		Height m
min–max, in
1/4 in.50015/64 in.218–.250
5/16 in.56219/64 in.280–.314
3/8 in.68823/64 in.341–.377
7/16 in.75027/64 in.403–.441
1/2 in.87531/64 in.464–.504
9/16 in.93835/64 in.526–.568
5/8 in1.06239/64 in.587–.631
3/4 in1.25047/64 in.710–.758
7/8 in1.43855/64 in.833–.885
1 in1.62563/64 in.956–1.012
1-1/8 in1.8121-7/64 in1.079–1.139
1-1/4 in2.0001-7/32 in1.187–1.251
1-3/8 in2.1881-11/32 in1.310–1.378
1-1/2 in2.3751-15/32 in1.433–1.505
1-5/8 in2.5621-19/32 in1.556–1.632
1-3/4 in2.7501-23/32 in1.679–1.759
1-7/8 in2.9381-27/32 in1.802–1.886
2 in3.1251-31/32 in1.925–2.013
2-1/4 in3.5002-13/64 in2.155–2.251
2-1/2 in3.8752-29/64 in2.401–2.505
2-3/4 in4.2502-45/64 in2.647–2.759
3 in4.6252-61/64 in2.893–3.013
3-1/4 in5.0003-3/16 in3.124–3.252
3-1/2 in5.3753-7/16 in3.370–3.506
3-3/4 in5.7503-11/16 in3.616–3.760
4 in6.1253-15/16 in3.862–4.014

Metric hex nuts

SizeISO 4032
s / m max, mm		Heavy hex B18.2.4.6M
s / m max, mm
M35.5 / 2.4–
M3.56 / 2.8–
M47 / 3.2–
M58 / 4.7–
M610 / 5.2–
M813 / 6.8–
M1016 / 8.4–
M1218 / 10.821 / 12.3
M1421 / 12.824 / 14.3
M1624 / 14.827 / 17.1
M1827 / 15.8–
M2030 / 1834 / 20.7
M2234 / 19.436 / 23.6
M2436 / 21.541 / 24.2
M2741 / 23.846 / 27.5
M3046 / 25.650 / 30.7
M3350 / 28.7–
M3655 / 3160 / 36.6
M3960 / 33.4–
M4265 / 3470 / 42
M4570 / 36–
M4875 / 3880 / 48
M5280 / 42–
M5685 / 4590 / 56
M6090 / 48–
M6495 / 51100 / 64

Nut heights used by the length finder. Inch: ASME B18.2.2-2022 heavy hex nuts, the usual nut for ASTM A193 / A320 studs (nut grades to ASTM A194); the 2015 edition’s 0.411 in maximum for 7/16 in is a misprint, below its own 27/64 in nominal. Metric: ISO 4032 style 1 and ASME B18.2.4.6M heavy hex nuts.

Threads

UNC or 8UN? Thread Series for Large Studs

UNC versus 8UN threads on large studs. Left: 2 inch thread profiles to scale, 2-4 1/2 UNC has a deeper thread than 2-8UN, stress area 2.50 against 2.77 square inches. Right: bar chart of the extra tensile stress area of 8UN over UNC for sizes 1 1/8 to 4 inch, from 3.2 percent at 1 1/4 inch to a peak of 11.1 percent at 2 1/2 inch, falling to 6.6 percent at 4 inch 2 in thread, to scale 0.136 2-4½ UNC: P 2/9 in As = 2.50 in² 0.077 2-8UN: P 1/8 in As = 2.77 in², +10.9 % Thread depth (root) to the dashed line; 1 in of thread shown 8UN stress area gain over UNC, % 0 4 8 12 1-1/8 in: UNC 7 thr./in A_s 0.763 in2, 8UN A_s 0.790 in2, +3.6 % 1⅛ 1-1/4 in: UNC 7 thr./in A_s 0.969 in2, 8UN A_s 1.000 in2, +3.2 % 1¼ 3.2 1-3/8 in: UNC 6 thr./in A_s 1.155 in2, 8UN A_s 1.234 in2, +6.8 % 1⅜ 1-1/2 in: UNC 6 thr./in A_s 1.405 in2, 8UN A_s 1.492 in2, +6.2 % 1½ 1-3/4 in: UNC 5 thr./in A_s 1.899 in2, 8UN A_s 2.082 in2, +9.6 % 1¾ 2 in: UNC 4.5 thr./in A_s 2.498 in2, 8UN A_s 2.771 in2, +10.9 % 2 2-1/4 in: UNC 4.5 thr./in A_s 3.248 in2, 8UN A_s 3.557 in2, +9.5 % 2¼ 2-1/2 in: UNC 4 thr./in A_s 3.999 in2, 8UN A_s 4.442 in2, +11.1 % 2½ 11.1 2-3/4 in: UNC 4 thr./in A_s 4.934 in2, 8UN A_s 5.425 in2, +10.0 % 2¾ 3 in: UNC 4 thr./in A_s 5.967 in2, 8UN A_s 6.506 in2, +9.0 % 3 3-1/4 in: UNC 4 thr./in A_s 7.099 in2, 8UN A_s 7.686 in2, +8.3 % 3¼ 3-1/2 in: UNC 4 thr./in A_s 8.329 in2, 8UN A_s 8.963 in2, +7.6 % 3½ 3-3/4 in: UNC 4 thr./in A_s 9.657 in2, 8UN A_s 10.339 in2, +7.1 % 3¾ 4 in: UNC 4 thr./in A_s 11.083 in2, 8UN A_s 11.813 in2, +6.6 % 4 6.6 Stud size, in (sizes with both UNC and 8UN) Aₛ = 0.7854 (D − 0.9743/n)², our calculation EXOTIC ALLOY
The 8-thread series keeps the thread shallow on large studs. At 2 in the UNC thread is 0.136 in deep, 8UN only 0.077 in; hover a bar for both stress areas.
  • UNC gets coarser with size: 7 threads per inch at 1-1/8 in, 4 from 2-1/2 in up.
  • 8UN keeps 8 threads per inch from 1-1/8 to 4 in; 1 in UNC already has 8.
  • More metal: the shallower thread leaves 3.2 to 11.1 % more tensile stress area.
  • UNF is listed only up to 1-1/2 in.
  • Pipe flanges: studs are usually ordered UNC up to 1 in and 8UN from 1-1/8 in.
SizeUNC
thr./in		As UNC
in²		As 8UN
in²		8UN gain
%
1-1/8 in70.7630.790+3.6
1-1/4 in70.9691.000+3.2
1-3/8 in61.1551.234+6.8
1-1/2 in61.4051.492+6.2
1-3/4 in51.8992.082+9.6
2 in4½2.4982.771+10.9
2-1/4 in4½3.2483.557+9.5
2-1/2 in43.9994.442+11.1
2-3/4 in44.9345.425+10.0
3 in45.9676.506+9.0
3-1/4 in47.0997.686+8.3
3-1/2 in48.3298.963+7.6
3-3/4 in49.65710.339+7.1
4 in411.08311.813+6.6

Stress area As = 0.7854 (D − 0.9743/n)² (ASME B1.1), our calculation. The nut must have the same thread series as the stud.

Strength

Stud Grades, Strength & Tensile Loads

Inch: ASTM A193 and A320

GradeMaterialDiameter
in		Tensile min
ksi		Yield min
ksi		Hardness maxNote
A193 B74140-type Cr-Mo, Q&T≤ 2½ / to 4 / to 7125 / 115 / 100105 / 95 / 75321 HBW, 35 HRCStandard high-temperature stud
A193 B7MCr-Mo, Q&T≤ 4 / to 7100 / 10080 / 75235 HBW, 99 HRBHardness-limited, sour service
A193 B16Cr-Mo-V, Q&T≤ 2½ / to 4 / to 8125 / 110 / 100105 / 95 / 85321 HBW, 35 HRCHigher temperatures
A193 B8, B8M Cl. 1304 / 316, solution treatedall7530223 HBW, 96 HRBCorrosion and cryogenic
A193 B8 Cl. 2304, strain hardened≤ ¾ / 1 / 1¼ / 1½125 / 115 / 105 / 100100 / 80 / 65 / 50321 HBW, 35 HRCStrength falls with size
A193 B8M Cl. 2316, strain hardened≤ ¾ / 1 / 1¼ / 1½110 / 100 / 95 / 9095 / 80 / 65 / 50321 HBW, 35 HRCStrength falls with size
A320 L7Cr-Mo, Q&T≤ 2½125105321 HBW, 35 HRCImpact tested at −150 °F (−101 °C)
A320 L434340 Ni-Cr-Mo, Q&T≤ 4125105321 HBW, 35 HRCImpact tested at −150 °F (−101 °C)

ASTM A193 (high-temperature and general service) and A320 (low-temperature service), minimum values. Austenitic Class 2 studs are strain hardened, so their strength falls as the diameter grows.

Metric: DIN 976-1 property classes

ClassMaterialRm min
MPa		Yield min
MPa		DIN 976-1 sizes
4.8Carbon steel420340M3–M39
5.6Carbon steel500300M3–M39
5.8Carbon steel520420M3–M39
8.8Carbon or alloy steel, quenched & tempered800 (≤ M16), 830640 (≤ M16), 660M3–M39
10.9Alloy steel, quenched & tempered1040940M3–M39
12.9Alloy steel, quenched & tempered12201100M3–M39
A2-70Stainless 304 type, cold worked700450M3–M24
A4-70Stainless 316 type, cold worked700450M3–M24

Steel to ISO 898-1, stainless to ISO 3506-1. Yield: lower yield or 0.2 % proof stress (for 4.8 and 5.8 the ISO 898-1 stress at 0.0048 d non-proportional elongation). DIN 976-1 also allows brass (CU2, CU3) and aluminium (AL1, AL2).

SizeAs
mm²		4.8
kN		5.6
kN		8.8
kN		10.9
kN		12.9
kN		A2-70 / A4-70
kN
M620.18.410.116.120.924.514.1
M836.615.418.329.338.144.725.6
M105824.429.046.460.370.840.6
M1284.335.442.267.487.7102.859.0
M1615765.978.5125.6163.3191.5109.9
M20245102.9122.5203.4254.8298.9171.5
M24353148.3176.5293.0367.1430.7247.1
M30561235.6280.5465.6583.4684.4–
M36817343.1408.5678.1849.7996.7–

Minimum ultimate tensile load = As × minimum tensile strength (ISO 898-1, ISO 3506-1), our calculation; 8.8 uses 830 MPa above M16. A2-70 / A4-70 only to M24 in DIN 976-1.

SizeThreadAs
in²		B7 tensile / yield
kip		B8M Cl. 1 tensile / yield
kip		B8M Cl. 2 tensile / yield
kip
1/2 in1/2-13 UNC0.14217.7 / 14.910.6 / 4.315.6 / 13.5
5/8 in5/8-11 UNC0.22628.3 / 23.717.0 / 6.824.9 / 21.5
3/4 in3/4-10 UNC0.33441.8 / 35.125.1 / 10.036.8 / 31.8
7/8 in7/8-9 UNC0.46257.7 / 48.534.6 / 13.946.2 / 36.9
1 in1-8 UNC0.60675.7 / 63.645.4 / 18.260.6 / 48.5
1-1/8 in1-1/8-8UN0.79098.8 / 83.059.3 / 23.775.1 / 51.4
1-1/4 in1-1/4-8UN1.000125.0 / 105.075.0 / 30.095.0 / 65.0
1-1/2 in1-1/2-8UN1.492186.5 / 156.6111.9 / 44.8134.3 / 74.6
1-3/4 in1-3/4-8UN2.082260.3 / 218.6156.2 / 62.5–
2 in2-8UN2.771346.3 / 290.9207.8 / 83.1–
2-1/2 in2-1/2-8UN4.442555.3 / 466.4333.2 / 133.3–
3 in3-8UN6.506748.2 / 618.1488.0 / 195.2–
3-1/2 in3-1/2-8UN8.9631030.8 / 851.5672.2 / 268.9–
4 in4-8UN11.8131358.5 / 1122.2886.0 / 354.4–

As × ASTM minimum tensile and yield strength, our calculation; UNC to 1 in, 8UN above. B8M Class 2 is covered to 1-1/2 in. 1 kip = 1,000 lbf = 4.448 kN.

Finder

Full Threaded Stud Length & Load Finder

Grip, washers, two nuts and the stick-out give the length; the grade gives the load.

Length of a full threaded stud for a bolted joint, M20 to scale: two 20 mm plates (grip 40 mm), a 3 mm washer and an ISO 4032 nut 18 mm high at each end, and at least two pitches (5 mm) standing out beyond each nut, need 92 mm, so the next DIN 976-1 length is 100 mm, which leaves 9 mm beyond each nut 9 nut m 18 3 grip 40 3 nut m 18 9 l = 100 mm, DIN 976-1 (next length above 92) Needed: grip 40 + 2 washers 3 + 2 nuts 18 + 2 × 2P (5) = 92 mm stick-out ≥ 2 pitches M20, ISO 4032 nut, ISO 7089 washer EXOTIC ALLOY
How the finder adds up the length, M20 example to scale. The result is rounded up to the next standard length, so the actual stick-out is usually longer than the minimum.

Stud & joint

Our calculation. Grip = total thickness clamped (flanges and gasket, or plates); washer = thickness of one washer under each nut (0 if none); stick-out = thread beyond each nut, in pitches. Nuts: ISO 4032, or heavy hex to ASME B18.2.4.6M (metric) or B18.2.2 (inch). Ends: DIN 976-1 Form A plain, Form B chamfered; ASME studs chamfered. Inch grades are ASTM A193 unless marked A320. Length = grip + 2 washers + 2 nut heights (maximum) + 2 stick-outs, rounded up to the next DIN 976-1 length, or to the next 1/4 in (1/2 in above 10 in) as overall LT. Loads = stress area × minimum strength of the grade.

Result
100
mm, DIN 976-1 length
203.4
kN min. tensile load
Length needed:92 mm
Stick-out per nut:9 mm (3.6 P)
Stress area:245 mm²
Min. yield load:161.7 kN
Mass each (steel):0.208 kg
Designation:DIN 976-1 Form A M20 × 100, class 8.8

Materials

Full Threaded Stud Materials & Coatings

MaterialGradesFinishWhere
Cr-Mo alloy steel (4140 type)ASTM A193 B7, B7M; A320 L7Plain, zinc, PTFE coatedFlanges, valves, pressure vessels
Ni-Cr-Mo alloy steel (4340)ASTM A320 L43Plain, PTFE coatedLow-temperature service, larger sizes
Carbon and alloy steelISO 898-1 4.8 to 12.9Plain, zinc, hot-dip galvanizedStructures, machinery, anchoring
Stainless 304 / 316ASTM A193 B8, B8M; A2-70, A4-70PlainCorrosive and cryogenic service
A-286 (iron-nickel superalloy)ASTM A453 Grade 660PlainHigh-temperature joints
Inconel 718ASTM A1014 (UNS N07718)PlainSubsea and high-temperature bolting
Duplex and super duplexUNS S32205, S32750, S32760PlainSeawater and offshore
Alloy steel
B7 · L7 · L43

The standard pressure-joint stud.

41404340
Stainless
B8 · B8M · A2 / A4

As in the photo.

304316
Nickel & duplex
718 · A-286 · S32760

Heat, seawater and sour service.

Inconel 718A-286S32760
Manufacturing

How Our Full Threaded Studs Are Made

1

Bar

Certified bar; B7 bar quenched and tempered.

2

Cut

Cut to length, ends faced square.

3

Thread

Thread rolled end to end; large sizes cut.

4

Chamfer

Ends chamfered to the root diameter.

5

Mark

Grade and maker’s mark on one end.

6

Finish

Coating, then bundling with nuts if ordered.

Applications

Where Our Full Threaded Studs Are Used

Pipe flanges

Flange joints in refineries, pipelines and process plants.

Pressure vessels

Manways, nozzles and heat exchanger channels.

Valves & pumps

Bonnets, casings and covers.

Low temperature

A320 L7 and B8 studs on cold and cryogenic lines.

Machinery

Tie rods, housings and adjustable stops.

Structures

Hangers, bracing and base plates from cut rod.

Quality & testing

Full Threaded Stud Inspection & Certification

CheckMethodApplied to
ThreadGO / NOT GO ring gaugesEvery lot
Chamfer UNOT GO major-diameter ring, 1–2 pitchesASME studs
LengthOverall, or first thread to first threadEvery lot
HardnessBrinell / RockwellEvery heat-treat lot
Tensile, yieldMachined or full-size testPer grade standard
ImpactCharpy V at test temperatureA320 grades
MaterialPMI / chemical analysisStainless and nickel alloys

Every shipment includes

  • EN 10204 3.1 certificate with heat number
  • Mechanical test and hardness results
  • Dimensional report

On request

  • EN 10204 3.2 with third-party inspection
  • Impact tests, PMI reports
  • Coating thickness reports
FAQ

Full Threaded Stud Questions, Answered

A headless rod threaded over its whole length, used with a nut at each end or screwed into a tapped hole at one end. ASME B18.31.2 calls it a continuous thread stud (1/4 to 4 in); the metric equivalent is DIN 976-1, Form A with plain ends and Form B with chamfered ends (M2 to M72).

It depends on the standard. An ASME B18.31.2 continuous thread stud is measured overall, end to end. An ASME flange bolting stud for ASME B16.5 flanges is measured from first full thread to first full thread, so the chamfered ends, 1 to 2 pitches each, come on top. DIN 976-1 studs are measured overall.

Both are threaded over their full length. Form A has plain ends, as cut from threaded rod; Form B has chamfered ends, which start more easily in a nut or tapped hole. DIN 976-1 also lists 1, 2 and 3 m lengths, the threaded rods formerly covered by the withdrawn DIN 975.

ASME B18.31.2 lists UNC, UNF (up to 1-1/2 in) and the 8-thread series 8UN (from 1-1/8 in). Studs for pipe flanges are usually ordered UNC up to 1 in and 8UN from 1-1/8 in. 8UN has a shallower thread and 3.2 to 11.1 % more tensile stress area than UNC; at 2 in it is 2.77 against 2.50 square inches.

For ASME B18.31.2 continuous thread studs: plus or minus 0.04 in up to 2-1/2 in long, 0.08 in to 4 in, 0.10 in to 8 in, 0.12 in to 16 in and 0.18 in above. For flange bolting studs: plus or minus 0.062 in up to 12 in, 0.125 in to 18 in and 0.250 in above.

Inch studs are mostly ASTM A193 B7 (125 ksi tensile and 105 ksi yield up to 2-1/2 in), B7M where hardness is limited, B16, stainless B8 and B8M, and ASTM A320 L7 or L43 for low temperatures. DIN 976-1 studs come in classes 4.8 to 12.9 (M3 to M39) and stainless A2-70 and A4-70 (M3 to M24).

We allow at least two pitches beyond each nut. The chamfered end of an ASME stud can be up to two pitches long, so less than that may leave an incomplete thread inside the nut. Our length finder adds this to the grip, the washers and the nut heights.

ASTM A193 requires the grade symbol and the maker's identification on one end of each stud; for studs smaller than 3/8 in (10 mm) marking is a matter of agreement. ASME B18.31.2 requires the stud ends to be suitable for marking.
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