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  2. API 6A

API 6A Bolting, API 6ACRA Bolting, API 6A718 Bolting

Fasteners, Stud Bolts, Studs, Bolting, Screws, Nuts, Washers

API 6A Closure Bolting shall be qualified, manufactured and marked in accordance with API 20 E & API 20F. Bolting Levels (BSLs) are specified in the below table.

Minimum Requirement of Closure Bolting

  API 20E API 20F
PSL 1 BSL-1 BSL-2
PSL 2 BSL-1 BSL-2
PSL3 BSL-1 BSL-2
PSL 4 BSL-2 (bolt nominal diameter ≤ 2 1/2 in.) BSL-2 (bolt nominal diameter ≤ 2 1/2 in.)
PSL 4 BSL-3 (bolt nominal diameter > 2 1/2 in.) BSL-3 (bolt nominal diameter > 2 1/2 in.)

API 6A Bolting Materials

Acceptabale Closure Bolting for 6B & 6BX Flanges & Studded Connections
 Product Pressure Rating MPa (psi) Nominal Size ( in .) ASTM Bolting Standard(s) and 0.2 % Offset Yield Strength
Nonexposed Bolting H2S-Exposed Bolting
A193 GR. B7 (≤ 2.5")
A320 GR. L7 (≤ 2.5")
A320 GR. L43 (≤ 4.0")		 A193 GR. B7 (˃ 2.5")
A320 GR. L7 (˃ 2.5")		 A13 GR. B7M (≤ 4.0")
A320 GR. L7M (≤ 2.5")		 A453 GR. 660D (≤ 4. 0" )
CRA
725 MPa (105 ksi) 655 MPa (95 ksi) 550 MPa (80 ksi) 725 MPa (105 ksi)
API 6A Studs, Bolts, and Cap Screws 13.8 (2000 ) All sizes ✔ NA ✔ ✔
20.7(3000 ) All sizes ✔ NA ✔ ✔
34.5 (5000 ) All sizes ✔ NA ✔ ✔
69. 0(10,000) 1 13/16, 2 1/16, 2 9/16,3 1/16 ✔ NA ✔ ✔
4 1/16 ✔ NA Unacceptable ✔
5 1/8 ✔ NA Unacceptable ✔
7 1/16 ✔ NA ✔ ✔
9, 11, 13 5/8, 18 3/4, 21 1/4 ✔ NA Unacceptable ✔
103.5(15,000 ) 14/5 ✔ NA ✔ ✔
2 1/16, 2 9/16,3 1/16, 4 1/16 ✔ NA Unacceptable ✔
5 1/8 ✔ NA ✔ ✔
7 1/16, 9, 11, 13 5/8 ✔ NA Unacceptable ✔
18 3/4 NA ✔ Unacceptable ✔
138.0(20,000 ) 1 13/16, 2 1/16, 2 9/16,3 1/16, 4 1/16, 7 1/16, 9 ✔ NA ✔ ✔
11, 13 5/8 ✔ Gr. L43 only ✔ ✔ Gr. B7M only ✔
API 6A Nuts All pressure ratings All sizes ASTM A194/A194M GR.2H, 2HM, 7, 7M ASTM A194/A194M GR.2HM, 7M
Allowable Closure Bolting by Temperature Class
Temperature Class P, S, T, U K, L
Impact testing of studs, bolts, and screws required No a Yes
Acceptable ASTM bolting standards and grades for studs, bolts, and screws A193/A193M GR.B7 A320/A320M GR.L7
A320/A320M GR.L7 A320/A320M GR.L43
A320/A320M GR.L43 A320/A320M GR.L7M
A193/A193M GR.B7M A453/A453M GR.660D
A320/A320M GR.L7M CRA
A453/A453M GR.660D -
CRA -
Acceptable ASTMs tandards and grades for nuts b ASTM A194/A194M ASTM A194/A194M
GR.2H, 2HM, 7, 7M GR.2H, 2HM, 7, 7M
Exposed Bolting (High Strength)

ASTM A453/A453M Grade 660D solution - treated and age hardened bolting shall be acceptable at a hardness o f HRC35 and lower, and a minimum 0.2 % offset yield strength of 725 MPa (105,000 psi ). Environmental and material limits specified in NACE MR0175/ISO15156 shall apply.

  • NOTE 1 - CRA materials may be used, provided they satisfy the minimum mechanical requirements of ASTM A453/A453M Grade 660D bolting, except that the maximum hardness shall meet NACE MR0175/ISO 15156 requirements .
  • NOTE 2 - NACE MR0175 provides material usage limits for H2S environments.Other forms of cracking may result from the presence of chlorides (such as seawater) and or hydrogen (such as cathodic protection ) .

ASTM A453/A453M Grade 660D solution treated and age hardened bolting as stated in should not be used on pressure containing and high load bearing connectors in the following situations :

  • wet/dry offshore and coastal applications in the presence of salt air;
  • where it is routine to clean/wash equipment with untreated/raw seawater .
  • NOTE 1 - Environmentally assisted cracking, such as s tress corrosion cracking (SCC), may result from the presence or accumulation of chlorides from deposited salt on highly stressed austenitic stainless steel bolting, such as Grade 660D .
  • NOTE 2 - API 6ACRA addresses alternative, higher-strength CRA materials suitable for sour exposure .

Exposed Bolting (Low Strength)

ASTM A193/A193M Grade B7M shall be acceptable at a minimum 0.2 % offset yield strength of 550 MPa (80, 000 psi ) for the flanges listed in Table for NACE MR01 75/ISO 1 51 56 exposed bolting ( low-strength ) .
ASTM A320/A320M Grade L7M shall be acceptable at a minimum 0 .2 % offset yield strength of 550 MPa (80,000 psi ) for the flanges listed in Table for NACE MR01 75/ISO 1 51 56 exposed bolting (low-strength ) only.
Only flanges having a bolt nominal diameter ≤ 63 .5 mm (≤ 2 .5 in. ) are acceptable for this grade of bolting .

Non-Exposed Boltiing

ASTM A193/A193M Grade B7 shall be acceptable for non exposed service for all flanges requiring a nominal bolt diameter ≤ 63 .5 mm (≤ 2.5 in.) and with temperature class P, S, T, and U.all bolting > 63.5 mm (> 2. 5 in.) Diameter shall require impact testing.
ASTM A320/A320M Grade L7 or L43 shall be acceptable for non exposed service for all flanges.
NOTE bolting make -up and connection capacity can be affected by miss matching the strength of the nut to the strength of the bolt. Bolting with diameters greater than38 mm (1. 50 in.) are typically affected more than smaller bolting.

Exposed Nuts

ASTM A194/A194M Grades 2HM and 7M shall be acceptable for all flange sizes and rated working pressures.
NOTE ASTM A453/A453M Grade 660D or CRA nuts may be used with NACE MR01 75/ISO 1 51 56 exposed bolting only if provisions are made to prevent galling.

API 6A Recommended Torque for All Bolting Types

Recommended Torques for Flange Bolting (SI Units)

Stud Diameter
D
in.		 Threads per in.
N
1/in.		 Studs with Sy = 550 MPa
Bolt Stress Equal to
275 MPa		 Studs with Sy = 720 MPa
Bolt Stress Equal to
360 MPa		 Studs with Sy = 655 MPa
Bolt Stress Equal to
327.5 MPa
Tension
F
kN		 Torque
f = 0.07
N-m		 Torque
f = 0.13
N-m		 Tension
F
kN		 Torque
f = 0.07
N-m		 Torque
f = 0.13
N-m		 Tension
F
kN		 Torque
f = 0.07
N-m		 Torque
f = 0.13
N-m
0.500 13 25 36 61 33 48 80 - - -
0.625 11 40 70 118 53 92 155 - - -
0.750 10 59 122 206 78 160 270 - - -
0.875 9 82 193 328 107 253 429 - - -
1.000 8 107 288 488 141 376 639 - - -
1.125 8 140 413 706 184 540 925 - - -
1.250 8 177 569 981 232 745 1285 - - -
1.375 8 21 9 761 1320 286 996 1727 - - -
1.500 8 265 991 1727 346 1297 2261 - - -
1.625 8 31 5 1263 221 1 41 2 1653 2894 - - -
1.750 8 369 1581 2777 484 2069 3636 - - -
1.875 8 428 1947 3433 561 2549 4493 - - -
2.000 8 492 2366 4183 644 3097 5476 - - -
2.250 8 631 3375 5997 826 4418 7851 - - -
2.500 8 788 4635 8271 1032 6068 10,828 - - -
2.625 8 - - - - - - 1040 6394 11 ,429
2.750 8 - - - - - - 11 46 7354 13,168
3.000 8 - - - - - - 1375 9555 17,1 56
3.250 8 - - - - - - 1624 12,1 54 21 ,878
3.750 8 - - - - - - 2185 18,685 33,766
3.875 8 - - - - - - 2338 20,620 37,293
4.000 8 - - - - - - 2496 22,683 41 ,057

Recommended Torques for Flange Bolting (USC Units)

Stud Diameter
D
in.		 Threads per in.
N
1/in.		 Studs with Sy = 80 ksi
Bolt Stress Equal to 40 ksi		 Studs with Sy = 105 ksi
Bolt Stress Equal to 52.5 ksi		 Studs with Sy = 95 ksi
Bolt Stress Equal to 47.5 ksi
Tension
F
lbf		 Torque
f = 0.07
ft-lbf		 Torque
f = 0.13
ft-lbf		 Tension
F
lbf		 Torque
f = 0.07
ft-lbf		 Torque
f = 0.13
ft-lbf		 Tension
F
lbf		 Torque
f = 0.07
ft-lbf		 Torque
f = 0.13
ft-lbf
0.500 13 5676 27 45 7,450 35 59 - - -
0.625 11 9040 52 88 11,865 68 115 - - -
0.750 10 13,378 90 153 17,559 118 200 - - -
0.875 9 18,469 143 243 24,241 188 31 9 - - -
1.000 8 24,230 213 361 31 ,802 279 474 - - -
1.125 8 31 ,618 305 523 41,499 401 686 - - -
1.250 8 39,988 421 726 52,484 553 953 - - -
1.375 8 49,340 563 976 64,759 739 1281 - - -
1.500 8 59,674 733 1278 78,322 962 1677 - - -
1.625 8 70,989 934 1635 93,1 73 1226 21 46 - - -
1.750 8 83,286 1169 2054 109,313 1534 2696 - - -
1.875 8 96,565 1440 2539 126,741 1890 3332 - - -
2.000 8 110,825 1750 3094 145,458 2297 4061 - - -
2.250 8 142,292 2496 4436 186,758 3276 5822 - - -
2.500 8 177,685 3429 61 18 233,21 2 4500 8030 - - -
2.625 8 - - - - - - 233,765 4716 8430
2.750 8 - - - - - - 257,694 5424 971 2
3.000 8 - - - - - - 309,050 7047 12,654
3.250 8 - - - - - - 365,070 8965 16,136
3.750 8 - - - - - - 491,099 13,782 24,905
3.875 8 - - - - - - 525,521 15,208 27,506
4.000 8 - - - - - - 561,108 16,730 30,282

API 6A Stud Bolt Length

API 6A Full Thread Stud Bolt Length for 6B Flange Connectors with "R" & "RX" Gaskets

API 6A Full Thread Stud Bolt Length for 6B Flange Connectors with R & RX Gaskets


Flange Size and Pressure Bolt Size and Thread Length* Flange Size and Pressure Bolt Size and Thread Length*
2 1/16 2000 5/8 - 11 UNC 5.000 7 1/16 2000 1 - 8 UNC 7.500
2 1/16 3000 7/8 - 9 UNC 6.500 7 1/16 3000 1 1/8 - 8 UN 8.500
2 1/16 5000 7/8 - 9 UNC 6.500 7 1/16 5000 1 3/8 - 8 UN 11.250
2 9/16 2000 3/4 - 10 UNC 5.500 9 2000 1 1/8 - 8 UN 8.500
2 9/16 3000 1 - 8 UNC 7.000 9 3000 1 3/8 - 8 UN 9.500
2 9/16 5000 1 - 8 UNC 7.000 9 5000 1 5/8 - 8 UN 12.500
3 1/8 2000 3/4 - 10 UNC 5.750 11 2000 1 1/4 - 8 UN 9.250
3 1/8 3000 7/8 - 9 UNC 6.500 11 3000 1 3/8 - 8 UN 10.000
3 1/8 5000 1 1/8 - 8 UN 7.750 11 5000 1 7/8 - 8 UN 14.250
4 1/16 2000 7/8 - 9 UNC 6.500 13 5/8 2000 1 1/4 - 8 UN 9.500
4 1/16 3000 1 1/8 - 8 UN 7.500 13 5/8 3000 1 3/8 - 8 UN 10.750
4 1/16 5000 1 1/4 - 8 UN 8.500 16 3/4 2000 1 1/2 - 8 UN 10.750
5 1/8 2000 1 - 8 UNC 7.250 16 3/4 3000 1 5/8 - 8 UN 12.250
5 1/8 3000 1 1/4 - 8 UN 8.250 21 1/4 2000 1 5/8 - 8 UN 12.250
5 1/8 5000 1 1/2 - 8 UN 10.500 20 3/4 3000 2-8 UN 15.000
  • FOOTNOTES* Tolerance on bolt length: +0.1 25/−0 in. for lengths up to 1 2 in. +0.250/ − 0 in. for lengths over 1 2 in.

API 6A Full Thread Stud Bolt Length for 6BX Flange Connectors

API 6A Full Thread Stud Bolt Length for 6BX Flange Connectors


Flange Size and Pressure Bolt Size and Thread Length * Flange Size and Pressure Bolt Size and Thread Length *
1 4/5 10,000 3/4 - 10 UNC 5.500 11 10,000 1 3/4 - 8 UN 15.250
1 4/5 15,000 7/8 - 9 UNC 6.000 11 15,000 2-8 UN 19.500
1 4/5 20,000 1 - 8 UNC 7.750 11 20,000 2 3/4 - 8 UN 23.750
2 1/16 10,000 3/4 - 10 UNC 5.500 13 5/8 5000 1 5/8 - 8 UN 12.750
2 1/16 15,000 7/8 - 9 UNC 6.500 13 5/8 10,000 1 7/8 - 8 UN 17.750
2 1/16 20,000 1 1/8 - 8 UN 8.500 13 5/8 15,000 2 1/4 - 8 UN 21.250
2 9/16 10,000 7/8 - 9 UNC 6.500 13 5/8 20,000 3-8 UN 29.750
2 9/16 15,000 1 - 8 UN 7.250 16 3/4 5000 1 7/8 - 8 UN 14.750
2 9/16 20,000 1 1/4 - 8 UN 9.500 16 3/4 10,000 1 7/8 - 8 UN 17.750
3 1/16 10,000 1 - 8 UNC 7.250 18 3/4 5000 2-8 UN 17.750
3 1/16 15,000 1 1/8 - 8 UN 8.000 18 3/4 10,000 2 1/4 - 8 UN 22.750
3 1/16 20,000 1 3/8 - 8 UN 10.250 18 3/4 15,000 3-8 UN 26.750
4 1/16 10,000 1 1/8 - 8 UN 8.500 21 1/4 5000 2-8 UN 19.000
4 1/16 15,000 1 3/8 - 8 UN 9.750 21 1/4 10,000 2 1/2 - 8 UN 24.750
4 1/16 20,000 1 3/4 - 8UN 12.500 26 3/4 2000 1 3/4 - 8 UN 14.250
5 1/8 10,000 1 1/8 - 8 UN 9.250 26 3/4 3000 2-8 UN 17.500
5 1/8 15,000 1 1/2 - 8 UN 11.500 30 2000 1 5/8 - 8 UN 14.500
7 1/16 10,000 1 1/2 - 8 UN 11.750 30 3000 1 7/8 - 8 UN 17.750
7 1/16 15,000 1 1/2 - 8 UN 13.000 - - - -
7 1/16 20,000 2-8 UN 17.750 - - - -
9 10,000 1 1/2 - 8 UN 13.500 - - - -
9 15,000 1 7/8 - 8 UN 16.000 - - - -
9 20,000 2 1/2 - 8UN 21.750 - - - -
  • FOOTNOTES* Tolerance on tap end thread length: +0.063/ − 0 in.** Tolerance on tap end stud length: +0.1 25/− 0 in.

API 6A Tap End Stud Bolt Length for 6B Flange Connectors with "R" & "RX" Gaskets

API 6A Tap End Stud Bolt Length for 6B Flange Connectors with R & RX Gaskets


Flange Size Size and Pressure Bolt and Thread Tap End Length* Nut End Length Length**
2 1/16 2000 5/8 - 11 UNC 0.761 1.563 3.625
2 1/16 3000 7/8 - 9 UNC 1.042 2.188 4.625
2 1/16 5000 7/8 - 9 UNC 1.042 2.188 4.625
2 9/16 2000 3/4 - 10 UNC 0.900 1.875 4.000
2 9/16 3000 1 - 8 UNC 1.188 2.500 5.125
2 9/16 5000 1 - 8 UNC 1.188 2.500 5.125
3 1/8 2000 3/4 - 10 UNC 0.900 1.875 4.1 25
3 1/8 3000 7/8 - 9 UNC 1.042 2.188 4.625
3 1/8 5000 1 1/8 - 8 UN 1.313 2.813 5.625
4 1/16 2000 7/8 - 9 UNC 1.042 2.188 4.625
4 1/16 3000 1 1/8 - 8 UN 1.313 2.813 5.500
4 1/16 5000 1 1/4 - 8 UN 1.438 3.1 25 6.125
5 1/8 2000 1 - 8 UNC 1.188 2.500 5.250
5 1/8 3000 1 1/4 - 8 UN 1.438 3.1 25 6.000
5 1/8 5000 1 1/2 - 8 UN 1.688 3.750 7.375
7 1/16 2000 1 - 8 UNC 1.188 2.500 5.375
7 1/16 3000 1 1/8 - 8 UN 1.313 2.813 5.875
7 1/16 5000 1 3/8 - 8 UN 1.563 3.438 7.500
9 2000 1 1/8 - 8 UN 1.313 2.813 5.875
9 3000 1 3/8 - 8 UN 1.563 3.438 6.750
9 5000 1 5/8 - 8 UN 1.813 4.063 8.500
11 2000 1 1/4 - 8 UN 1.438 3.1 25 6.500
11 3000 1 3/8 - 8 UN 1.563 3.438 7.000
11 5000 1 7/8 - 8 UN 2.063 4.688 9.625
13 5/8 2000 1 1/4 - 8 UN 1.438 3.1 25 6.625
13 5/8 3000 1 3/8 - 8 UN 1.563 3.438 7.375
16 3/4 2000 1 1/2 - 8 UN 1.688 3.750 7.500
16 3/4 3000 1 5/8 - 8 UN 1.813 4.063 8.375
21 1/4 2000 1 5/8 - 8 UN 1.813 4.063 8.375
20 3/4 3000 2-8 UN 2.188 5.000 10.125
  • FOOTNOTES* Tolerance on tap end thread length: + 0.063/− 0 in.** Tolerance on t ap end stud length: + 0.1 25/− 0 in.

API 6A Tap End Stud Bolt Length for 6BX Studded Flange Connectors

API 6A Tap End Stud Bolt Length for 6BX Studded Flange Connectors


Flange Size and Pressure Bolt Size and Thread Tap End Length * Nut End Length Length ** Flange Size and Pressure Bolt Size and Thread Tap End Length * Nut End Length Length **
1 13/16 10,000 3/4- 10 UNC 0.900 1.875 3.750 11 10,000 13/4- 8 UN 1.938 4.375 9.750
1 13/16 15,000 7/8 - 9 UNC 1.042 2.188 4.1 25 11 15,000 2-8 UN 2.188 5.000 12.000
1 13/16 20,000 1 - 8 UNC 1.188 2.500 5.125 11 20,000 23/4- 8 UN 2.938 6.875 15.000
2 1/16 10,000 3/4- 10 UNC 0.900 1.875 3.875 13 5/8 5000 1 5/8 - 8 UN 1.813 4.063 8.375
2 1/16 15,000 7/8 - 9 UNC 1.042 2.188 4.375 13 5/8 10,000 1 7/8 - 8 UN 2.063 4.688 11.000
2 1/16 20,000 1 1/8 - 8 UN 1.313 2.813 5.750 13 5/8 15,000 2 1/4 - 8 UN 2.438 5.625 13.250
2 9/16 10,000 7/8 - 9 UNC 1.042 2.188 4.375 13 5/8 20,000 3-8 UN 3.188 7.500 18.1 25
2 9/16 15,000 1 - 8 UNC 1.188 2.500 4.875 16 3/4 5000 1 7/8 - 8 UN 2.063 4.688 9.500
2 9/16 20,000 1 1/4 - 8 UN 1.438 3.1 25 6.250 16 3/4 10,000 1 7/8 - 8 UN 2.063 4.688 11.000
3 1/16 10,000 1 - 8 UNC 1.188 2.500 5.000 18 3/4 5000 2-8 UN 2.188 5.000 11.250
3 1/16 15,000 1 1/8 - 8 UN 1.313 2.813 5.500 18 3/4 10,000 2 1/4 - 8 UN 2.438 5.625 14.000
3 1/16 20,000 13/8- 8 UN 1.563 3.438 6.750 18 3/4 15,000 3-8 UN 3.188 7.500 16.750
4 1/16 10,000 1 1/8 - 8 UN 1.313 2.813 5.750 21 1/4 5000 2-8 UN 2.188 5.000 11.750
4 1/16 15,000 13/8- 8 UN 1.563 3.438 6.500 21 1/4 10,000 2 1/2- 8 UN 2.688 6.250 15.125
4 1/16 20,000 13/4- 8 UN 1.938 4.375 8.375 263/4 2000 13/4- 8 UN 1.938 4.375 9.125
5 1/8 10,000 1 1/8 - 8 UN 1.313 2.813 6.000 263/4 3000 2-8 UN 2.188 5.000 11.000
5 1/8 15,000 1 1/2- 8 UN 1.688 3.750 7.625 30 2000 1 5/8 - 8 UN 1.813 4.063 9.250
7 1/16 10,000 1 1/2- 8 UN 1.688 3.750 7.750 30 3000 1 7/8 - 8 UN 2.063 4.688 11.000
7 1/16 15,000 1 1/2- 8 UN 1.688 3.750 8.375 - - - - - -
7 1/16 20,000 2-8 UN 2.188 5.000 11.125 - - - - - -
9 10,000 1 1/2- 8 UN 1.688 3.750 8.500 - - - - - -
9 15,000 1 7/8 - 8 UN 2.063 4.688 10.1 25 - - - - - -
9 20,000 2 1/2- 8 UN 2.688 6.250 13.750 - - - - - -
    FOOTNOTES* Tolerance on bolt length: +0.1 25/−0 in. for lengths up to 1 2 in. +0.250/ − 0 in. for lengths over 1 2 in.

API 6A Full Thread Stud Bolt Length for 6B Flange Connectors with "R" Gaskets UNSC Series

API 6A Full Thread Stud Bolt Length for 6B Flange Connectors with R Gaskets UNSC Series


Flange Size and Pressure Bolt Size and Thread Length* Flange Size and Pressure Bolt Size and Thread Length*
2 1/16 2000 5/8 - 11 UNC 4.750 7 1/16 2000 1 - 8 UNC 7.250
2 1/16 3000 7/8 - 9 UNC 6.250 7 1/16 3000 1 1/8 - 8 UN 8.250
2 1/16 5000 7/8 - 9 UNC 6.250 7 1/16 5000 1 3/8 - 8 UN 11.000
2 9/16 2000 3/4 - 10 UNC 5.250 9 2000 1 1/8 - 8 UN 8.250
2 9/16 3000 1 - 8 UNC 6.750 9 3000 1 3/8 - 8 UN 9.250
2 9/16 5000 1 - 8 UNC 6.750 9 5000 1 5/8 - 8 UN 12.250
3 1/8 2000 3/4 - 10 UNC 5.500 11 2000 1 1/4 - 8 UN 9.000
3 1/8 3000 7/8 - 9 UNC 6.250 11 3000 1 3/8 - 8 UN 9.750
3 1/8 5000 1 1/8 - 8 UN 7.500 11 5000 1 7/8 - 8 UN 14.000
4 1/16 2000 7/8 - 9 UNC 6.250 13 5/8 2000 1 1/4 - 8 UN 9.250
4 1/16 3000 1 1/8 - 8 UN 7.250 13 5/8 3000 1 3/8 - 8 UN 10.500
4 1/16 5000 1 1/4 - 8 UN 8.250 16 3/4 2000 1 1/2 - 8 UN 10.500
5 1/8 2000 1 - 8 UNC 7.000 16 3/4 3000 1 5/8 - 8 UN 12.000
5 1/8 3000 1 1/4 - 8 UN 8.000 21 1/4 2000 1 5/8 - 8 UN 11.750
5 1/8 5000 1 1/2 - 8 UN 10.250 20 3/4 3000 2-8 UN 14.500
  • FOOTNOTES* Tolerance on bolt length:+0.1 25, −0 in. for lengths up to 1 2 in. +0.250, −0 in. for lengths over 1 2 in.

API 6A Tap End Stud Bolt Length for 6B Flange Connectors with "R" Gaskets UNSC Series

API 6A Tap End Stud Bolt Length for 6B Flange Connectors with R Gaskets UNSC Series


Flange Size and Pressure Bolt Size and Thread Tap End Length* Nut End Length Length** Flange Size and Pressure Bolt Size and Thread Tap End Length* Nut End Length Length**
2 1/16 2000 5/8 - 11 UNC 0.761 1.563 3.375 7 1/16 2000 1 - 8 UNC 1.188 2.500 5.000
21/16 3000 7/8 - 9 UNC 1.042 2.188 4.375 7 1/16 3000 1 1/8 - 8 UN 1.313 2.813 5.625
2 1/16 5000 7/8 - 9 UNC 1.042 2.188 4.375 7 1/16 5000 1 3/8 - 8 UN 1.563 3.438 7.250
2 9/16 2000 3/4- 10 UNC 0.900 1.875 3.750 9 2000 1 1/8 - 8 UN 1.313 2.813 5.625
2 9/16 3000 1 - 8 UNC 1.188 2.500 4.750 9 3000 1 3/8 - 8 UN 1.563 3.438 6.375
2 9/16 5000 1 - 8 UNC 1.188 2.500 4.750 9 5000 1 5/8 - 8 UN 1.813 4.063 8.1 25
3 1/8 2000 3/4- 10 UNC 0.900 1.875 3.875 11 2000 1 1/4 - 8 UN 1.438 3.1 25 6.125
3 1/8 3000 7/8 - 9 UNC 1.042 2.188 4.375 11 3000 1 3/8 - 8 UN 1.563 3.438 6.625
3 1/8 5000 1 1/8 - 8 UN 1.313 2.813 5.250 11 5000 1 7/8 - 8 UN 2.063 4.688 9.250
4 1/16 2000 7/8 - 9 UNC 1.042 2.188 4.375 13 5/8 2000 1 1/4 - 8 UN 1.438 3.1 25 6.250
41/16 3000 1 1/8 - 8 UN 1.313 2.813 5.125 13 5/8 3000 1 3/8 - 8 UN 1.563 3.438 7.000
4 1/16 5000 1 1/4 - 8 UN 1.438 3.1 25 5.750 16 3/4 2000 1 1/2 - 8 UN 1.688 3.750 7.1 25
51/8 2000 1 - 8 UNC 1.188 2.500 4.875 16 3/4 3000 1 5/8 - 8 UN 1.813 4.063 8.000
5 1/8 3000 1 1/4 - 8 UN 1.438 3.1 25 5.625 21 1/4 2000 1 5/8 - 8 UN 1.813 4.063 8.000
5 1/8 5000 1 1/2- 8 UN 1.688 3.750 7.000 203/4 3000 2-8 UN 2.188 5.000 9.625
  • FOOTNOTES* Tolerance on tap end thread length: +0.063/− 0 in.** Tolerance on tap end stud length; +0.1 25/− 0 in.