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Manufacture and Distribute Fasteners for Energy

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Stud Bolts

Xylan Coated Bolts

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Xylan Coated Bolts
Xylan Coated Bolts

Xylan Coated Bolts: Enhancing Performance and Safety in Industrial Applications

Xylan coatings have been a cornerstone in improving the performance and longevity of bolts, particularly in demanding environments like those found in the oil and chemical industries. For years, various Xylan formulations, including the classic 1010, 1070, 1014, and 1052, have been applied to bolts to address critical maintenance challenges. Today, Xylan 1424 is a prominent coating, building on the legacy of these earlier formulations.

The Benefits of Xylan Coatings on Bolts

The adoption of Xylan-coated bolts by major oil and chemical companies underscores their significant advantages for high-pressure flange connections. These coatings offer a range of properties that directly translate into operational benefits:

  • Optimized Torque Control: Xylan coatings provide excellent make-up and break-out torque characteristics. This means that bolts can be tightened to the correct specifications more consistently and loosened with less effort, reducing the risk of overtightening or seizing.
  • Reduced Maintenance Risks and Costs: By minimizing friction and preventing corrosion, Xylan coatings significantly reduce the need for high-risk cutting torches or costly bolt-cutting equipment during maintenance. This enhances worker safety and streamlines maintenance procedures.
  • Enhanced Lubricity: Many Xylan formulations are renowned for their lubricity. For instance, Xylan 1014 is valued for its good lubricity, alongside its chemical and abrasion resistance. Xylan 1052 is specifically highlighted for its excellent lubricity, making it ideal for applications where smooth assembly and disassembly are paramount. The early pioneers, Xylan 1070 and 1010, were also chosen for their lubricity and chemical inertness.
  • Corrosion and Chemical Resistance: Xylan coatings create a protective barrier that shields bolts from corrosive elements and harsh chemicals, extending their lifespan and maintaining structural integrity.

Advancing Towards a Greener Economy

In response to increasing environmental regulations and the focus on reducing volatile organic compounds (VOCs), PPG (the manufacturer of Xylan) has developed Xylan 1424, a low-VOC version. Companies like Sigma apply this coating to achieve the necessary performance in bolted connections while remaining compliant with environmentally conscious practices. This development supports the shift towards a “green economy” without compromising on the critical performance attributes of the coating.

Aesthetic and Identification Features

Beyond their functional benefits, Xylan coatings offer a practical advantage in terms of identification and branding. Xylan coated bolts are available in a wide array of colors, allowing companies to coordinate them with their standard corporate branding schemes. While very light shades are possible, the most common hues range from dark yellow to black, with popular choices including reds, blues, and greens. This color coding can also aid in the easy identification of specific bolt types or applications during installation and maintenance.

Do you have any specific applications in mind where Xylan-coated bolts could be beneficial, or would you like to know more about the technical specifications of a particular Xylan formulation?

L7M Bolts

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ASTM L7M Custom Bolts

ASTM A320 Grade L7M bolting is designned for low temperature sour gas service where there is high concertration of Hydrogen Sulfide gases present in prodcution situation. Per the specification at Sigma Fasteners we have our own heat treating furnace and hardness testing equipmet for onsite L7M modification and hardness testing. All L7M bolts require 100% hardness testing and at Sigma we keep it in house for complete control over the quality your products demand.

Stud Bolts

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Stud Bolts

Stud Bolts
Stud Bolts

Stud bolts are available in ASTM Grades B7, L7, B16, B16M, L7M, B8, 660 and B8M; they are also available exotic metals such as Monel, Titanium, Inconel, Alloy 20, and Hastelloy, 17-4PH. These studs are also available with industrial coatings such as SermaGard, Xylan, PTFE, Fluoropolymers and other coatings.

Stud Bolts for Pressure-Temperature Piping

  • Continuous Thread Studs (Fully Threaded Studs)

Stud bolts are threaded end to end and are often used for flange bolting with two nuts on either end.

There are two types of these studs.

  • Type one – usually for general purpose; the length of stud is measured from end to end. Threads are UNRC-2A.
  • Type two – studs for high temperature pressure piping. These studs are made to dimensional standard requirements of ANSI B16.5 the length of this stud is measured from first thread to first thread, exclusive of points. Threads are UNRC-2A for sizes 1 inch and under and 8 UNR-2A for sizes over 1 inch. The length of stud bolt, measured parallel to the axis, is the distance from first thread to first thread. First thread is defined as the intersection of the major diameter of the thread with the base of the point.

Double End Stud Bolts

Tap End Stud Bolts

ASTM Material Selection Chart

Double End Studs

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Double End Studs – Double ended studs

Double End Studs Bolts
Double End Studs

At Sigma Fasteners we provide mission critical bolting products for the nations leading manufacturers of pressure control equipment for controlling pressures during drilling and oil production.

Double-end studs used by many of these manufacturers have equal-length threads on each end to accommodate a nut and are threaded to a Class 2A fit. Length of stud is measured overall. Both ends have chamfered points, but round points may be furnished on either or both ends at the manufacturer’s option, This style is furnished in the same four types listed for tap-end studs. Double-end studs are used for flange bolting or other applications where torching from both ends is necessary or desirable.

Most steel grades not heat treated or quenched and tempered can be furnished on special order for production quantities. Only the Type 2 continuous thread studs made to specification ASTM A193 grade B7 are stocked in a full range of sizes.

ASTM Material Selection Chart B7, B7M, L7, L7M, 660, 718 Inconel, MP35N

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.

Tap End Stud – AWHEM Recommendation

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D Diameter – Nominal Stud Sizes

Tap End Stud
Tap End Stud

L Length – Measured end to end
T For 6B & 6BX studded flange connections with R, RX & BX gaskets, thread length maximum on end = 1 diameter + 1.5 pitch + 1/16-0
N Nut end thread length for 6B & 6BX studded flange connections with R, RX & BX gaskets shall be 2-1/2 diameters of full thread minimum.
* Class of Threads – Tap end threads may be furnished in any class thread specified. Nut end threads shall be American Standard Coarse or Fine series, Class 2A or 8 UN.

When ordering, please specify:
Diameter (D); Length (L); End-to-end dimension. (If length is figured first thread to first thread, order
must so specify.)
Tap end thread length (T) and thread series
Nut end thread length (N) and thread series

Double End or Tap End Studs are available in either rolled or cut threads. When the threads are rolled,
the full thread dimensions will increase slightly, and the diameter of the bodies will be undersized to the
pitch diameter of the thread.
Tap End Studs are available in ASTM A193 Grades of material or special materials. Sigma stocks the most
frequently used sizes of tap end studs in ASTM A193 Grade B7. Tap end studs can also be plated or
coated if allowances are made for coating thickness and thread fit.

Prints should be furnished on Double end or Tap End studs whenever possible.
** American Association of Wellhead Manufacturers –

TECHNICAL REPORT TR9501 Revision A

RECOMMENDATION FOR INTERCHANGEABLE STUD BOLTS AND TAP END STUDS FOR API SPEC 6A FLANGES