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Coated Bolts

SermaGard Coated Bolts

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ASTM F1428 – 92(2005) – Standard Specification for Aluminum Particle-Filled Basecoat/Organic or Inorganic Topcoat, Corrosion Protective Coatings for Fasteners

The ASTM F1428 specification as applied by Sigma Fasteners covers the corrosion-resistant coating system consisting of an inorganic aluminum particle-filled basecoat (SermaGard 1105) and an organic topcoat (SermaGard 1280 or Xylan 1014). The SermaGard basecoat is a water soluble slurry containing aluminum particles, a ceramic oxide pigment dispersed in a liquid binder of chromate/phosphate compounds. The organic topcoat consist of polymer and / or Fluoropolymer resins and pigments. At Sigma Fasteners these coatings are applied by conventional spray methods. The maximum service temperature of the coating system is 450° F (230° C). The coating system has a low susceptibility to inducing hydrogen embrittlement in steel parts of tensile strengths ≥ than 1000 MPa (≈RC31)

This coating system specification can be applied to alloy steels (ASTM A193 Grade B7),  ferritic and austenitic stainless steels (ASTM A193 GradeB8 and Grade B8M).

This coating system is in use in major offshore drilling, chemical and petrochemical facilities in the United States and worldwide.

SermaGard 1105 (ASTM F1428)

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.

SermaGard 1280

SermaGard 1280 is a fluorocarbon topcoat, which when applied to SermaGard 1105 basecoat gives
superior corrosion resistance and UV protection.

Moly Coated Bolts

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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.

Xylan Coated Bolts

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Xylan Coated Bolts
Xylan Coated Bolts

Xylan Coated Bolts

Xylan 1010, 1070, 1014, 1052 and now 1424 have been used as bolt coatings for almost a quarter century now. Most major Oil and Chemical Companies recognizing that maintenance is a huge issue have made coated bolt specifications for bolted high pressure flange connections. The various properties on the Xylan give excellent make up and brake out torque and reduce the need for high risk cutting torches or high cost bolt cutting when maintenance is required.

Xylan 1014 in bolt coatings used for its good lubricity, chemical and abrasion resistance.

Xylan 1052 for coated bolts used for its excellent lubricity.

Xylan 1070 and 1010 where the pioneers in the field – used for the lubricity and chemical inertness.

With VOCs an ever present issue these days Whitford has made a low VOC version 1424 which Sigma applies to achieve the results need in a coated bolt connection and to stay complaint in a green economy.

Xylan coated bolts come in many tints and the coated bolts are often coordinated with standard corporate color branding schemes. While very light shades are possible most of the popular hues range from a Dark Yellow to black with Reds and Blues and greens being the most widespread.

Zinc Phosphate Coating

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Zinc Phosphate coating is a crystalline conversion coating that is formed on a metal substrate. The phosphate process relies on the chemical reaction between the metal and the mildly acidic phosphate liquid to form insoluble crystalline phosphates on the surface of the part.

The phosphate coating is used as a pretreatment prior to painting, increasing corrosion protection, and providing for a better adhesion of the coating system.

When phos is used alone or in combination with oil (phos and oil) it lowers friction characteristics of sliding components or threaded parts. While typically called phos coating, phosphate alone has poor rust inhibiting characteristics and must be used in combination with oil or a top coat for corrosion protection. Zinc Phosphate can be applied to Ferric metals, but has no effect on Stainless Steel.

Phosphate Coating Characteristics
Color: dark gray / black
Typical Use: Anti –Galling/Basecoat
Top Coat: Oil or Paint

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

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.