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ASME B18.31.2 · B18.31.1M · DIN 2509

Double End Stud Bolts Manufacturer in India

The same thread at both ends, a nut on each and a plain shank through the joint. We make double end stud bolts to ASME B18.31.2, ASME B18.31.1M and DIN 2509 in A193 B7, B8M, classes 8.8 to 10.9 and stainless. Below: how long the threads are, full dimension tables, how the stud sits in a joint and a length finder.

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  • ISO 9001:2015 certified manufacturer
  • Equal threads, plain shank
  • Inch and metric
  • EN 10204 3.1 / 3.2
Stainless steel double end studs with plain shank
Inch 1/4 – 4 in Metric M6 – M100 Ends equal threads
Overview

ASME B18.31.2 & DIN 2509 Studs (Double End Stud Bolts): Manufacturer & Stockist

A double end stud has the same thread at both ends and a plain shank between them. A nut on each end clamps the joint, and the shank can lie in the joint itself.

Exotic Alloy manufactures double end studs in Mumbai, India, and keeps common sizes and grades in stock for process plants, pump and compressor makers, fabricators and maintenance teams. We supply across India and export to Uzbekistan, Central Asia, the Gulf and Africa.

Double end, tap end or full thread?

Equal threads and a nut at each end make a double end (clamping-type) stud. With a short metal end for a tapped hole it is a tap end stud; threaded right through, a full threaded stud; with a thinner shank, a reduced shank stud; for pipe flange sets see flange bolting.

ASME B18.31.2 ASME B18.31.1M DIN 2509 Full body B7 / 8.8 / A4-70
Double end stud at a glance
Inch
ASME B18.31.2 clamping type, 1/4 to 4 in
Metric
ASME B18.31.1M, M6–M100; DIN 2509, M12–M100
Threads
Same length both ends; UNC, UNF, 8UN; ISO metric
Thread B
2D + 1/4 in up to 10 in long
Length
Overall LT, end to end (ASME)
Grades
A193 B7, B8M; 5.6, 8.8, 10.9; stainless
Related
Tap end, full threaded, nuts
ASME B18.31.2 clamping-type double end stud 3/4-10 UNC by 5 inch, full body, drawn to scale: the same thread length B, at least 1.75 inch, at both ends, a plain shank of body diameter ds between them, chamfered ends with the chamfered thread distance U of up to 0.200 inch, and the overall length L T of 5 inches measured end to end B ≥ 1.75 B ≥ 1.75 plain shank, ds min .735 LT = 5 in overall, end to end (±0.10 in) U ≤ .200 U ≤ .200 D Size 3/4-10 UNC × 5 in Both ends same thread, nut on each B at LT ≤ 10 in 1.75 in (= 2D + 1/4) Shank full body ds ≈ D ASME B18.31.2 clamping-type double end stud, full body, to scale EXOTIC ALLOY
A 3/4-10 UNC × 5 in clamping-type double end stud to ASME B18.31.2, to scale. At this length each end has at least 1.75 in of full thread; U is the chamfer to the first full thread.
Specification

Double End Stud Specification

The range we manufacture and supply.

Inch standardASME B18.31.2 clamping-type double-end stud, full body
Metric standardsASME B18.31.1M clamping type; DIN 2509 full shank
Sizes1/4–4 in; M6–M100 (ASME), M12–M100 (DIN 2509)
LengthsTo order; overall length LT
ThreadsUNC, UNF, 8UN; ISO metric coarse; equal at both ends
GradesASTM A193 B7, B7M, B16, B8, B8M; A320 L7; 5.6, 8.8, 10.9; A2 / A4-70
OptionsShort or long thread (DIN 2509), spigot with flats, reduced body
FinishPlain, zinc plated, hot-dip galvanized, PTFE (fluoropolymer) coated
CertificationEN 10204 3.1; 3.2 on request
SupplyStuds alone or with two nuts and washers
Types

ASME Clamping-Type & DIN 2509 Double End Studs

Three standards for the same idea, each with its own details.

DIN 2509 double end stud M24 with full shank, drawn to scale for a length of 160 mm: equal threads b of 36 mm (short thread) at both ends, thread undercuts g of up to 3.5 pitches next to the shank, shank ds of about 24 mm, and on one end a spigot of 14 mm diameter dp with two flats 11 mm apart (s) and 6 mm long (z); end view shows the spigot flats b 36 (short) b 36 (short) g ≤ 3.5P g ≤ 3.5P full shank ds 23.79–24 l = 160 z 6 flats s 11 spigot end (enlarged) spigot dp 14 DIN 2509 double end stud M24 × 160, short thread, to scale EXOTIC ALLOY
DIN 2509 M24 × 160, to scale. An undercut next to each thread and a spigot with two flats on one end set it apart from the ASME studs.
TypeStandardThreadsShankSizes
Clamping type, inchASME B18.31.2Equal, B min by length; chamfered endsFull or reduced body1/4–4 in
Clamping type, metricASME B18.31.1MEqual, b min by length; chamfered endsFull or reduced bodyM6–M100
Double end stud, full shankDIN 2509Equal, short or long; undercut gFull shank; spigot with flatsM12–M100

DIN 2509 lists property classes 5.6 and 8.8; the long thread is listed up to M39. Reduced body studs are on our reduced shank page.

Dimensions

Double End Stud Dimensions

SizeNut-end thread B min, both ends
LT ≤ 10 / ≤ 16 / > 16 in		U max
UNC / UNF / 8UN		Body ds min
UNC / UNF / 8UN
1/4 in3/4 / 1 / 1-1/2.100 / .071 / –.241 / .243 / –
5/16 in7/8 / 1-1/8 / 1-5/8.111 / .083 / –.303 / .304 / –
3/8 in1 / 1-1/4 / 1-3/4.125 / .083 / –.364 / .367 / –
7/16 in1-1/8 / 1-3/8 / 1-7/8.143 / .100 / –.426 / .428 / –
1/2 in1-1/4 / 1-1/2 / 2.154 / .100 / –.488 / .491 / –
9/16 in1-3/8 / 1-5/8 / 2-1/8.167 / .111 / –.550 / .552 / –
5/8 in1-1/2 / 1-3/4 / 2-1/4.182 / .111 / –.611 / .615 / –
3/4 in1-3/4 / 2 / 2-1/2.200 / .125 / –.735 / .739 / –
7/8 in2 / 2-1/4 / 2-3/4.222 / .143 / –.859 / .863 / –
1 in2-1/4 / 2-1/2 / 3.250 / .167 / –.983 / .987 / –
1-1/8 in2-1/2 / 2-3/4 / 3-1/4.286 / .167 / .2501.106 / 1.112 / 1.108
1-1/4 in2-3/4 / 3 / 3-1/2.286 / .167 / .2501.231 / 1.237 / 1.233
1-3/8 in3 / 3-1/4 / 3-3/4.333 / .167 / .2501.354 / 1.362 / 1.358
1-1/2 in3-1/4 / 3-1/2 / 4.333 / .167 / .2501.479 / 1.487 / 1.483
1-5/8 in3-1/2 / 3-3/4 / 4-1/4– / – / .250– / – / 1.608
1-3/4 in3-3/4 / 4 / 4-1/2.400 / – / .2501.727 / – / 1.733
1-7/8 in4 / 4-1/4 / 4-3/4– / – / .250– / – / 1.858
2 in4-1/4 / 4-1/2 / 5.444 / – / .2501.975 / – / 1.983
2-1/4 in4-3/4 / 5 / 5-1/2.444 / – / .2502.225 / – / 2.233
2-1/2 in5-1/4 / 5-1/2 / 6.500 / – / .2502.473 / – / 2.483
2-3/4 in5-3/4 / 6 / 6-1/2.500 / – / .2502.723 / – / 2.733
3 in– / 6-1/2 / 7.500 / – / .2502.973 / – / 2.982
3-1/4 in– / 7 / 7-1/2.500 / – / .2503.223 / – / 3.232
3-1/2 in– / 7-1/2 / 8.500 / – / .2503.473 / – / 3.482
3-3/4 in– / 8 / 8-1/2.500 / – / .2503.723 / – / 3.732
4 in– / 8-1/2 / 9.500 / – / .2503.973 / – / 3.982

ASME B18.31.2-2014 Table 2, clamping-type studs, inch. B: minimum full thread at each end by overall length LT; U: chamfer to the first full thread, 1 to 2 pitches; ds: full-body shank, maximum = D.

LTTolerance
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

ASME B18.31.2 clamping-type studs, tolerance on the overall length LT; mm converted.

SizePitch PThread b min, both ends
LT ≤ 250 / ≤ 400 / > 400 mm		U max
2P		Body ds min
LT ≤ 150 / > 150
M6118 / 24 / –25.82 / 5.7
M81.2518 / 24 / –*2.57.78 / 7.64
M101.526 / 32 / 4539.78 / 9.64
M121.7530 / 36 / 493.511.73 / 11.57
M14234 / 40 / 53413.73 / 13.57
M16238 / 44 / 57415.73 / 15.57
M202.546 / 52 / 65519.67 / 19.48
M24354 / 60 / 73623.67 / 23.48
M303.566 / 72 / 857– / 29.48
M36478 / 84 / 978– / 35.38
M424.590 / 96 / 1099– / 41.38
M485– / 108 / 12110– / 47.38
M565.5– / 124 / 13711– / 55.26
M646– / 140 / 15312– / 63.26
M726– / 156 / 16912– / 71.26
M806– / 172 / 18512– / 79.26
M906– / – / 20512– / 89.13
M1006– / – / 22512– / 99.13

ASME B18.31.1M Table 2, metric clamping-type studs, mm. b: minimum thread at each end (maximum b + 2P). *M8 is listed with 18 / 24 mm; every other size follows 2d + 6 / 2d + 12 / 2d + 25, which would give 22 / 28 mm for M8, so confirm M8 thread length on the order.

SizePitch PThread b, short
min–max		Thread b, long
min–max		Shank ds
min		Spigot dp / flats s / z
M121.7521–23.523–25.511.828 / 7 / 4
M16225–2828–3115.8212 / 10 / 5
M202.530–3434–3719.7914 / 11 / 6
M24336–40.540–44.523.7914 / 11 / 6
M27338–42.543–47.526.7918 / 13 / 6
M303.542–4747–5229.7918 / 13 / 6
M333.544–4950–5532.7525 / 22 / 9
M36450–5655–6135.7525 / 22 / 9
M39452–5858–6438.7528 / 24 / 10
M424.557–64–41.7528 / 24 / 10
M454.558–65–44.7532 / 27 / 11
M48564–71.5–47.7532 / 27 / 11
M52568–75.5–51.736 / 30 / 12
M565.573–81–55.736 / 32 / 13
M605.576–84–59.742 / 36 / 14
M64682–91–63.742 / 36 / 14
M72 × 6689–98–71.750 / 41 / 15
M80 × 6695–104–79.750 / 41 / 15
M90 × 66103–112–89.6550 / 41 / 15
M100 × 66111–120–99.6550 / 41 / 15

DIN 2509:2016, mm; nominal values = maximum for ds, dp and s, nominal z. Undercut g ≤ 3.5 P next to each thread; M72 to M100 have a 6 mm pitch.

Thread length

How Long Are the Threads? It Depends on the Stud Length

Minimum thread length B at each end of an ASME B18.31.2 double end stud against its overall length L T, for 1/2, 1 and 2 inch studs: B is 2D plus 1/4 inch up to 10 inches long, 2D plus 1/2 inch from 10 to 16 inches and 2D plus 1 inch above 16 inches; for example 1.25, 1.5 and 2 inches for a 1/2 inch stud Minimum thread B at each end vs. stud length LT, inch 0 1 2 3 4 5 6 0 4 8 10 12 16 20 24 overall length LT, in B, in 1/2 in stud, L_T up to 10 in: B min 1-1/4 in 1/2 in stud, L_T 10 to 16 in: B min 1-1/2 in 1/2 in stud, L_T over 16 in: B min 2 in 1/2 in 1 in stud, L_T up to 10 in: B min 2-1/4 in 1 in stud, L_T 10 to 16 in: B min 2-1/2 in 1 in stud, L_T over 16 in: B min 3 in 1 in 2 in stud, L_T up to 10 in: B min 4-1/4 in 2 in stud, L_T 10 to 16 in: B min 4-1/2 in 2 in stud, L_T over 16 in: B min 5 in 2 in B = 2D + 1/4, then 2D + 1/2 above 10 in, 2D + 1 above 16 in each line starts at LT = 2B (shortest stud with both threads) EXOTIC ALLOY
The minimum thread steps up at 10 and 16 in of stud length. Longer studs get longer threads, so the nuts have room on long, thick joints. Hover a point for the value.
  • Inch: B = 2D + 1/4, 2D + 1/2 or 2D + 1 in.
  • Metric ASME: b = 2d + 6, 2d + 12 or 2d + 25 mm.
  • DIN 938–940 nut ends: the same numbers, but switching at 125 and 200 mm.
  • DIN 2509: fixed short or long thread, whatever the length.
Sizeb = 2d + 6b = 2d + 12b = 2d + 25
M10263245
M12303649
M16384457
M20465265
M24546073
M30667285
M36788497
M429096109
DIN 938–940, used forl ≤ 125 mm125 < l ≤ 200 mml > 200 mm
ASME B18.31.1M, used forLT ≤ 250 mm250 < LT ≤ 400 mmLT > 400 mm

Thread lengths in mm. ASME B18.31.1M and DIN 938 / 939 / 835 / 940 (nut end) share these values; only the length breaks differ.

In the joint

A Double End Stud in a Bolted Joint

A double end stud in a bolted joint, to scale: ASME B18.31.1M M20 clamping-type stud through two 30 mm plates (grip 60 mm), a 3 mm washer and an 18 mm ISO 4032 nut at each end and at least two pitches beyond each nut need 112 mm, rounded to 120 mm; the 46 mm thread at each end carries the nut and runs 16 mm into the joint, the plain shank lies in the middle of the joint thread b 46 thread b 46 9 nut 18 3 grip 60 3 nut 18 9 LT = 120 mm (needed 112) thread runs 16 mm into the joint M20, ISO 4032 nuts, ISO 7089 washers EXOTIC ALLOY
M20 clamping-type stud through a 60 mm joint, to scale. Each 46 mm thread carries its nut and runs on into the joint; the plain shank sits in the middle.

Three checks for every stud

  • Length: grip + 2 washers + 2 nuts + stick-out at both ends.
  • Thread under each nut: the thread must reach past the nut, or the nut runs onto the shank before it clamps.
  • Shank: if the two threads would meet, the stud is threaded throughout; order a full threaded stud instead.
M20 examplemm
Grip (two 30 mm plates)60
2 washers + 2 nuts (ISO 4032)6 + 36
2 × 2 pitches stick-out10
Needed / ordered LT112 / 120
Thread b each end (LT ≤ 250)46
Thread into the joint, each side16

Our calculation; ordered length rounded up to the next 10 mm.

Finder

Double End Stud Length Finder

Length, thread under each nut and the load the stud carries.

Stud & joint

Our calculation. Grip = total thickness clamped; washer = one washer under each nut (0 if none); stick-out = thread beyond each nut, in pitches. Nuts: ISO 4032 or ASME B18.2.4.6M heavy hex (metric), ASME B18.2.2 heavy hex (inch), maximum height. Length = grip + 2 washers + 2 nuts + 2 stick-outs, rounded up to 1/4 in (inch) or to 5 mm up to 100 mm, 10 mm up to 200 mm and 20 mm above (our steps). Thread b from the standard for that length; DIN 2509 length l excludes the spigot. Loads = stress area × minimum strength.

Result
120
mm overall LT
46
mm thread b, each end
Length needed:112 mm
Stick-out each end:9 mm (3.6 P)
Thread past each nut:19 mm
Plain shank:28 mm
Min. tensile load:203.4 kN
Mass each (steel):261 g
Designation:ASME B18.31.1M clamping-type stud M20 × 2.5 × 120, class 8.8

Materials

Double End Stud Materials & Coatings

MaterialGradesFinishWhere
Cr-Mo alloy steel (4140 type)ASTM A193 B7, B7M; A320 L7Plain, PTFE coated, zincFlanges, valves, pressure equipment
Cr-Mo-V alloy steelASTM A193 B16PlainHigh-temperature joints
Carbon and alloy steelISO 898-1 5.6, 8.8, 10.9Plain, zinc, hot-dip galvanizedMachinery and structures
Stainless 304 / 316A2-70, A4-70; A193 B8, B8MPlainFood, chemical and marine plant, as in the photo
Nickel alloys and duplexInconel 718, A-286, S32760PlainHeat, seawater and sour service
Alloy steel
B7 · L7 · 8.8

Pressure and machinery joints.

41404340
Stainless
A2 · A4 · B8M

As in the photo.

304316
Nickel & duplex
718 · A-286 · S32760

Heat, seawater and sour service.

Inconel 718A-286S32760
Manufacturing

How Our Double End Studs Are Made

1

Bar

Certified bar, heat treated for the grade.

2

Cut

Cut to length, ends faced and chamfered.

3

First end

Thread rolled to length b.

4

Second end

Same thread; shank left plain.

5

Mark

Grade and maker’s mark on one end.

6

Finish

Coating, then bundling with nuts if ordered.

Applications

Where Our Double End Studs Are Used

Flanged joints

Pipe, valve and vessel flanges with a nut each side.

Pumps & compressors

Casings, covers and split housings.

Pressure equipment

Heat exchanger channels and manways.

Machinery

Tie bolts, frames and gearbox housings.

Food & chemical plant

Stainless studs on washdown equipment.

Structures

Through connections in steelwork.

Quality & testing

Double End Stud Inspection & Certification

CheckMethodApplied to
Both threadsGO / NOT GO ring gaugesEvery lot
Thread length bAgainst the length bandEvery lot
Chamfer UNOT GO major-diameter ring, 1–2 pitchesASME studs
LT, shank dsHeight gauge, micrometerEvery lot
Hardness, tensileTo ISO 898-1 or ASTMEvery heat-treat lot
MaterialPMI / chemical analysisStainless and alloys

Every shipment includes

  • EN 10204 3.1 certificate with heat number
  • Dimensional and thread gauge report
  • Lot number on every bundle

On request

  • EN 10204 3.2 with third-party inspection
  • Impact tests for A320 grades
  • PMI and coating reports
FAQ

Double End Stud Questions, Answered

A stud threaded for the same length at both ends with a plain shank between them, used with a nut at each end. ASME B18.31.2 calls it a clamping-type double-end stud with equal ends. A stud with a short metal end for a tapped hole is a tap end stud.

For ASME B18.31.2 and ASME B18.31.1M double end studs the nominal length is the overall length, end to end, including the chamfered ends. The length tolerance for inch studs runs from plus or minus 0.04 in for studs up to 2-1/2 in long to plus or minus 0.18 in above 16 in.

ASME B18.31.2 gives a minimum thread length B at each end of 2D + 1/4 in for studs up to 10 in long, 2D + 1/2 in up to 16 in and 2D + 1 in above, so a 1/2 in stud up to 10 in long has at least 1.25 in of thread at each end. Metric ASME studs use 2d + 6, 2d + 12 and 2d + 25 mm.

The numbers are the same, 2d + 6, 2d + 12 and 2d + 25 mm, as on the nut end of DIN 938 to 940 studs, but ASME B18.31.1M changes to the longer thread at 250 and 400 mm stud length, DIN at 125 and 200 mm. The ASME tables list 18 and 24 mm for M8, where the rule would give 22 and 28 mm.

A metric double end stud with a full shank, M12 to M100, made with a short or a long thread at both ends, an undercut next to each thread and a spigot with two flats on one end. DIN 2509 lists property classes 5.6 and 8.8; other classes and materials by agreement.

Add the grip, a washer and a nut at each end and at least two pitches of thread beyond each nut. Then check that the thread at each end is longer than the stick-out plus the nut, so the nut tightens on full thread. Our finder does both.

On a full body stud the plain shank is about the thread diameter. On a reduced body stud the shank is turned down below the thread diameter. Both are covered by ASME B18.31.2; this page covers full body studs, reduced body studs have their own page.

Inch double end studs are made in ASTM A193 B7, B7M, B16, B8 and B8M and ASTM A320 L7; metric studs in property classes 5.6, 8.8 and 10.9 and in stainless A2-70 and A4-70. The studs in our photo are stainless steel.
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