Xylan Coating

Stud Bolts, Nuts, Screws, Threaded Rod & Washers

Xylan is the largest, most complete line of fluoropolymer coatings in the world. Xylan coatings have a broad range of properties which make them ideal for an infinite variety of applications.
Xylan coatings differ from traditional fluoropolymer coatings in one very important aspect: they are composite materials. Lubricants with the lowest known coefficient of friction are combined in a matrix with the newest high temperature
resistant organic polymers. Xylan Coatings offer many benefits for offshore service. These include resistance to corrosion and chemical attack, superb sub- sea visibility, lower maintenance costs and less downtime. United, these polymers form
“plastic alloys” with highly beneficial properties :

• Low friction : as low as 0.02.
• Superb wear resistance: even under extreme pressure.
• Outstanding corrosion and chemical resistance: in most environments.
• Wide operating-temperature range: from -195°C to +285°C (-385°F to +545°F).
• Flexible curing schedule: ambient to 425°C (800°F).
• Wear resistance : even under extreme pressures.
• Corrosion and chemical resistance : in most environments.
• Weather resistance : against sunlight, saltwater, road chemicals, many hostile environments.
• Wide color range : color-code your product.
• Pliability : Xylan coatings will bend freely and repeatedly without breaking.
• Machinability : apply multiple coats of Xylan coating (most formulations) and mill to specification.
• Excellent adhesion : to most metals, plastics, ceramics, wood, even to itself (most formulations).

Xylan Coated Stud Bolts

Fluoropolymer coatings have the lowest coefficient of friction of all known fastener coatings, which requires that “makeup torque” specification be adjusted to compensate.
Many factors affect the determination of the ideal torque value to achieve
recommended clamping loads (K-factor). The coefficient of friction (CoF) is only one. The K (or nut) factor varies, since it is the net effect of many variables such as type of fastener, thread, thread angle, type of pretreatment, etc. It would
be inappropriate for Whitford to offer K-factor information when Xylan is only one of the many variables involved. The same lot of Xylan 1424 applied to different types of fasteners can result in a reduction of makeup torque from 30 all the way
to 70 percent, caused by the differences in fasteners. Note: Makeup torque will not vary on fasteners of the same size and make.

Every bolted joint is unique, and the optimum tightening torque should be determined for each by careful testing. A properly tightened bolt is stretched so that it acts like a rigid spring, pulling the mating surfaces together. Whitford recommends
a direct-tension (load-cell) study for every size and type of fastener you are using, routine practice in the construction industry.

Corrosion comes in many forms: atmospheric, galvanic, chemical, fretting, salt-fog, etc.
Stainless steel needs oxygen to provide an oxide layer that inhibits corrosion. So it would not be fair to compare Xylan to stainless steel in an ASTM B-117
salt-fog test when the end use is buried in hot soil. Of course stainless steel will outperform Xylan in the salt-fog test, although Xylan will outperform stainless steel when buried in hot soil.
In coastal environments, stainless steel is susceptible
to chloride-induced stress-corrosion cracking (chemical corrosion). Xylancoated carbon-steel bolts are not affected by chlorides.
Stainless-steel fasteners also gall and seize. It is common knowledge that stainless-steel fasteners need to be
retorqued after 24 hours due to galling, losing up to 40% of their clamping force in 24 hours. But Xylan-coated carbonsteel fasteners reach the required clamp load on the first makeup.
When stainless steel is combined with dissimilar metals,
galvanic corrosion results. Xylancoated carbon steel in combination with any alloy does not lead to galvanic corrosion.
Perhaps the most striking difference of all is that stainless-steel fasteners can cost twice as much as Xylan-coated carbon-steel
fasteners.

Cf is a term much misunderstood and depends upon many factors including pressure, speed and temperature. The friction of Xylan coatings is relatively constant over a range of increasing pressure from 0.2 psi to 400,000 psi and from liquid hydrogen
temperatures of -420° to +550°F (-250° to 285°C). As speed increases, the Cf increases but remains well below (better than) the values of other dry-film lubricants. Because of the film transfer of PTFE from coating to mating part, frictional values
are similar for all mating materials as long as the surface finish is 50rms or better (smoother). Frictional oscillation (stick-slip, chatter) is virtually nonexistent. It is this ability to perform uniformly over a wide range of conditions that
distinguishes these coatings from other dry-film lubricants.