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Coated Bolts

Fluoropolymer Coated Bolt Torque

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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.

Coated Bolts

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Xylan Coated Bolts

Improve Make up and break out torque of bolts. Xylan is a fluoropolymer topcoat manufactured by Whitford Corporation, which in the 1014 and 1070 coatings afford high lubricity (co-efficient of friction as low as .02), and corrosion resistance of approximately 1000 hours(ASTM B117) when applied over phosphate, and up to 2000 hours when applied over electroplating. These are solvent based thin film topcoats. These Xylan products have a maximum temperature ranging up to 500 deg. F.  Xylan 1000 and 1400 series may also be applied over other basecoats, for added corrosion protection.  The 1400 series coatings by Whitford (typically 1424), are low voc coatings. They have a coefficient of friction of .05 to .10, and a maximum constant operating temperature of 400 deg. F. The corrosion resistance of the 1400 series is approximately 1500 hours, when applied over a suitable basecoat such as zinc electroplating.

Sermagard Coated Bolts

Sigma Fasteners is a licensed applicator for Sermagard products. 1105 is a ceramic-metallic sprayed basecoat that at 1 mil of thickness or more affords 3000-4000 hours of ASTM B117 salt spray resistance, with an appropriate topcoat. It can be used at high temperatures. It is extremely effective in salt atmospheres. The Sermagard 1105 process involves curing at high temperatures (Minimum of 750 deg. (F) and subsequent burnishing with appropriate blast media to achieve conductivity. Sermagard 1105 contains aluminum flake and Chromate. Sermagard 1280 is a fluorocarbon topcoat, which when applied to Sermagard 1105 basecoat gives superior corrosion resistance and UV protection.

Moly Coated Bolts

Molybdenum disulfide coated bolts are commonly used to improve the performance in extremes of load carrying capacity, operating temperature and coefficient of friction. This coating provides effective lubrication in a wide range of loads, in many cases exceeding 250,000 psi. Moly coatings lubricate sacrificially by transferring lubricant between the two mating surfaces, which helps to reduce both wear and the coefficient of friction. Moly coatings are a combination of molybdenum disulfide lubricant and high performance resins. The coating is thermally cured to bond thoroughly with the base metal of the coated part. Moly coated bolts can solve problems associated with corrosion, chemical exposure, and abrasion. offer excellent corrosion and chemical resistance and a barrier protection better than phosphate. With Moly’s exceptional barrier protection, it is appropriate for more severe environments and is often used in chemical processing and oil field equipment.

PTFE Coated Bolts

Over  seventy years ago a DuPont scientist, discovered polytetrafluoroethylene (PTFE) — a fluoropolymer that is corrosive chemical and heat resistance, and the world’s most slippery surface.  PTFE Coated Bolts have a Low Coefficient of Friction – The coefficient of friction of PTFE is generally in the range of 0.05 to 0.20, depending on the load, sliding speed, and particular PTFE coating used. PTFE Coated Bolts are Nonwetting – Since surfaces coated with PTFE are both oleophobic and hydrophobic, they are not readily wetted. Cleanup is easier and more thorough—in many cases, surfaces are self-cleaning. PTFE Coated Bolts are Heat Resistance – PTFE industrial coatings can operate continuously at temperatures up to 260°C/500°F.  PTFE Coated Bolts have Cryogenic Stability – Many PTFE industrial coatings withstand severe temperature extremes without loss of physical properties. PTFE industrial coatings may used at temperatures as low as -270°C/-454°F. PTFE Coated Bolts are Chemical Resistance – PTFE is normally unaffected by chemical environments. The only chemicals known to affect all PTFE industrial coatings are molten alkali metals and highly reactive fluorinating agents.

Coated Bolt Torque Chart