Sigma Fasteners

Manufacture and Distribute Fasteners for Energy

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Sigma Fasteners

Coated Bolts

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Sigma Fasteners manufacturers coated studs to meet major Chemical and Oil Company specifications. Sizes range from 1/2 inch – 3 1/2 and larger.

Blue Coated Stud Bolts
Coated Stud Bolts

Sigma coated bolts have a two-layer structure of special pretreatment polymer film and under-treatment layer. Phosphate Pre-treatment technique insures the physical performance of product without changing and fluropolymer top coating results in a better performance in resisting chemical and seawater corrosion. SermaGard coating is different from PTFE because of their strong corrosion resistant ability. Xylan can be different per customers request to meet various environmental working conditions.

  • Xylan
  • SermaGard
  • PTFE
  • PTFE
  • Moly

Xyan combined with an advanced treatment technology; the film is thin but is excellent in corrosion resistance which prolongs the lifespan of the product.  Non-stick and low friction properties can make-up the torque coefficient which is easy to install and disassembling. Property of chemical & weather resistance make it suitable to various severe environments.

Xyaln and SermaGard coatings are the best choice in offshore, oilfield and petrochemical precision equipment against corrosion. Its properties are particularly suitable for surface corrosion prevention of underwater precision equipment including Christmas tree, BOP and pipelines and other parts.

Xylan coating properties:

Low friction ( as low as 0.055)

Remarkable adhesion

Unusual resistance to wear and abrasion

Excellent resistance to corrosion

Resistance to chipping

Resistance to the elements: weather, sunlight, salt water

Working temperature range from: -190 to + 260° C

Available in a wide range of colors

Duplex Stainless Bolts

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Duplex Stainless Bolts

Duplex stainless has twice the yield strength of conventional austenitic stainless steels. Duplex stainless has high corrosion cracking resistance

Duplex Stainless Double End Studs Bolts
Duplex Stainless Double End Studs

and high resistance to corrosion pitting as well as good general corrosion resistance in a wide variety of environments. Duplex stainless is the choice in extremely corrosive environments or were wear resistance and galling resistance is required. Many chemical environments not hospitable for standard 18-8 stainless is handled by Duplex stainless bolts. Duplex Stainless bolting handles nitric, hydrofluoric and phosphoric acids well at ambient temperatures. At elevated temperatures in chloride or sea water environments duplex stainless bolts have resistance to pitting and stress corrosion cracking superior to 316 stainless. Duplex stainless in various forms is used widely in heat exchangers, petroleum refining, offshore, petrochemical, pulp and paper industries.
Duplex stainless in typical Annealed condition has an ultimate tensile strength of 105 ksi.

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    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.

    Bolting And Ring Gasket Requirements

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    Bolting Requirements for FlangesASME/ANSI B16.5 – 1996 – Pipe Flanges and Flanged Fittings

    The ASME B16.5 – 1996 Pipe Flanges and Flange Fittings, flange bolt and gasket standard covers pressure-temperature ratings, materials, dimensions, tolerances, marking, testing, and methods of designating openings for pipe flanges and flanged fittings.

    The standard includes flanges with rating class designations 150, 300, 400, 600, 900, 1500, and 2500 in sizes NPS 1/2 through NPS 24, with requirements given in both metric and U.S units. The Standard is limited to flanges and flanged fittings made from cast or forged materials, and blind flanges and certain reducing flanges made from cast, forged, or plate materials. Included in this Standard are requirements and recommendations regarding flange bolting, flange gaskets, and flange joints. The standard covers the required number of bolts, diameter of the stud bolts, length of stud bolts and ring size in R, 1RF, RTJ, and RX  gaskets.

    Flange Bolt Requirements

    High Strength Super Alloy Bolts

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    17-4 custom bolts

    High Strength Super Alloy Bolts

    17-4 is a precipitation hardening Stainless steel alloy. This chromium-nickel grade stainless steel has excellent mechanical strength. It corrosion resistance and high strength properties hold up very well in high temperature service up to 800 degrees F.  17-4 is used for high strength and elevated temperatures as well as in applications where high fatigue strength is required. 17-4 has good resistance to galling, seizing and stress corrosion. The corrosion resistance of 17-4 is superior to other chromium nickel stainless alloys.

    17-4 Multiple Conditions available:

    H 1100 – Tensile Strength 140 ksi

    HH 1150 – Tensile Strength 135 ksi

    13-8 Custom Bolts

    13-8 is a precipitation hardening stainless steel. It is much like 17-4 in that it is a high strength stainless while possessing excellent corrosion resistance. 13-8 stainless alloy is used when good stress corrosion cracking resistance is required.

    660 Custom Bolts

    ASTM A453 660 Grade A,B or D a heat treated and age hardened version of A-286 is a popular high temperature precipitation hardened alloy. The high strength and oxidation resistance up to 1500 degrees F. 660 has excellent corrosion resistance up to 1300 degrees F and has fair salt spray corrosion resistance.

    Material Selection Chart

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      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