Fluoropolymer Coated Bolt Torque

March 19, 2010 by · Leave a Comment 

API 6A is an International Standard which specifies requirements and gives recommendations for the performance, dimensional and functional interchangeability, design, materials, testing, inspection, welding, marking, handling, storing, shipment, purchasing, repair and re-manufacture of wellhead and well tree equipment for use in the petroleum and natural gas industries.

Torque Value Chart

Download Torque Value Chart

Covering bolts on Wellhead Equipment, Valves and chokes, and loose flanged connectors.

TORQUE FOR FLANGE BOLTING (B7/L7 STUDS)*

ANSI / API 6A / ISO 10423:2003 Feb. 1, 2005

ASTM A193 Grade B7 Tensile and Yield Strength
2 1/2″ and under – tensile  125 ksi; yield strength 105 ksi
Over 2 1/2″ to 4″ – tensile 115 ksi; yield 95 ksi
Over 4″ to 7″
– tensile 100; yield 75 ksi

ASTM A320 L7 Tensile and Yield Strength
Only covers 2 1/2″ and under
- tensile  125 ksi; yield strength 105 ksi

Source: API 6-A, 19th Appendix D, Table D1 &
D2

Stud Diameter Tension PTFE Coated Bolt coefficient of Friction Plain Bolt coefficient of Friction
Size Ibf Torque Torque Torque Torque
Inch Nm Ft. lbs Nm Ft. lbs
f=0.07 f=0.07 f=0.13 f=0.13
1/2″ 7450 48 35 80 59
5/8″ 11865 92 68 155 115
3/4″ 17559 160 118 270 200
7/8″ 24241 253 188 429 319
1″ 31802 376 279 639 474
1 1/8″ 41499 540 401 925 686
1 1/4″ 52484 745 553 1285 953
1 3/8″ 64759 996 739 1727 1281
1 1/2″ 78322 1297 962 2261 1677
1 5/8″ 93173 1653 1226 2894 2146
1 3/4″ 109313 2069 1534 3636 2696
1 7/8″ 126741 2549 1890 4493 3332
2″ 145458 3097 2297 5476 4061
2 1/4″ 186758 4418 3276 7851 5822
2 1/2″ 233212 6068 4500 10828 8030
2 5/8″ 233765 6394 4716 11429 8430
2 3/4″ 257694 7354 5424 13168 9712
3″ 309050 9555 7047 17156 12654
3 1/4″ 365070 12154 8965 21878 16136
3 3/4″ 491099 18685 13782 33766 24905
3 7/8″ 525521 20620 15208 37293 27506
4″ 561108 22683 16730 41057 30282

*This chart is for general practice purposes only and should not be in the engineering or design of any products. The most current edition of the API specification may be obtained on the API Standards website to make sure you have the most current edition of API 6A. For most the accurate references in critical situations torque values should be replaced with field measured tension values. Accurate stud tension is difficult to attain using torque, because friction has a significant effect on the torque–tension relationship. Any thread damage (however minor), additional lubrication, or standard deviations within the range can change friction and thereby the expected outcome.