ASTM A453 Grade 660 Class D API 6A Full Thread Stud Bolt

For products monogrammed per API 6A 21st Edition, all closure bolting shall be qualified and manufactured in accordance with API 20F (Corrosion-Resistant Bolting Requirements).

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 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.

What does ASTM A453 Grade 660 Class D require?

ASTM A453 Grade 660 Class D is solution treated at 1650 ± 25 °F [900 ± 14 °C] for 2 h min or 1800 ± 25 °F [980 ± 14 °C] for 1 h min and liquid quenched, then aged at 1325 ± 25 °F [720 ± 14 °C] for 16 h and air cooled, with a second age at 1200 ± 25 °F [650 ± 14 °C] for 16 h if needed to reach the properties (A453/A453M-17 Table 4). Table 5 requires up to 2½ in. [63.5 mm]: 130 ksi [895 MPa] tensile and 105 ksi [725 MPa] yield; over 2½ in. [63.5 mm]: 120 ksi [825 MPa] tensile and 95 ksi [655 MPa] yield; 15 % elongation, 18 % reduction of area and 248 to 321 HB (24 to 35 HRC) in both size ranges.

Class D does not require a stress-rupture test and is stamped NR in addition to the other required markings (8.2.1, 9.1). Each bolting component carries the grade symbol and class (660 D) and the thread type: M1 or M2 for machined threads, R1 or R2 for rolled threads, formed after (1) or before (2) the precipitation heat treatment (6.1.1, 9.1). The 35 HRC maximum matches the ISO 15156-3 (NACE MR0175) limit for UNS S66286. API 20F covers Grade 660 Class D for BSL-2 and BSL-3 bolting, and API 6A (21st edition) 8.2.3.6 cautions against Grade 660D on pressure-containing connectors in salt-air offshore or coastal service, or where equipment is washed with raw seawater. See the ASTM A453 660D (Class D) specification, ASTM A453 Grade 660 chemical composition and mechanical properties.

Make-up torque: API 6A Bolting Torque for Flanges (SI Units) and API 6A Bolting Torque for Flanges (USC Units).

Source: ASTM A453/A453M-17; API 6A 21st edition; API 20F; ISO 15156-3. Last reviewed .

Specifications
  • ASTM A453
  • ASTM A638
  • EN 10269
  • EN 10083-3
  • ISO 3506-5
  • DIN 267
Surface Treatments
  • Xylan 1070 / 1014 / 1400 / 1424
  • Xylar 2 / 101
  • SermaGard 1105 / 1280
  • Dacromet 320 / 500
  • TakeCoat 1000 Ceramic
  • Magnigard
  • MolyKote
Certifications
  • ISO 9001 - 2015 Certified
  • PED 2014/68/EC
  • NACE MR0175/ISO 15156-2
  • NORSOK M-650
  • DFAR
  • MERKBLATT AD 2000 W2/W7/W10
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