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Fastener Help Articles Individual

2 years ago Land Chennai   522 views

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Location: Chennai
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You may have heard of "Blue Bolt Coating", its real name is Whitford Xylan® Coating... and it isn't always blue. Many of our customers ask for the "Blue Bolt Coating", but what exactly is Xylan and when should it be used?


Xylan is a blend of fluoropolymers, engineering plastics and selected corrosion inhibitors which, when combined, create these characteristics in fasteners:

  • Low friction

  • Exceptional adhesion

  • Unusual resistance to wear and abrasion

  • Excellent corrosion resistance

  • Resistance to chipping

  • Resistance to the weather, sunlight and salt water

Xylan's versatility is best demonstrated as a coating for stud Bolts and nuts, where it provides unparalleled performance in ease of installation, corrosion resistance and ease of removal. It can be used on standard alloy steel nuts and bolts, or can be paired with stainless steel fasteners for even more benefits.

Xylan fastener coatings or "Blue Bolt Coatings" are typically specified in oil and waterworks applications.


A bolt’s function essentially boils down to applying a high enough Hose Clamps force that when external forces are applied, transverse movement and separation cannot occur. Using calibrated torque tools to tighten fasteners and apply that clamp force is far superior to going by the user’s judgement or feeling. Or, as one senior technician calls it “The One Grunt or Two Grunts Method”. Measuring torque alone, however, does not ensure a proper installation.

1. Torque is an indirect indicator of Tension.

Torque is the measurement of twisting force needed to thread the fasteners together.

2. Tension is the force that actually holds an assembly together. Put another way:

A bolt can stretch similar to a spring, as it becomes tightened once all the parts of the assembly are brought together.

The higher the torque applied to the fastener, the more tension is created as the bolt stretches.


If a bolt is like a spring and more torque equals more tension, why does not a certain amount of torque always result in the same amount of tension?

Though the relationship between torque and tension is linear, many other factors can affect this relationship. Some of these factors include surface texture, rust, oil, debris, material type, locking elements and human error. Because of these variables, tightening to a specific torque setting can create varied results in the field or on the assembly line.


General commodity commercial fasteners do not fall under the umbrella of products that would require a UL listing or ICC-ES report. There are three main governing bodies that cover specifications for fasteners. ASTM (American Society for Testing and Materials) covers primarily bolts and fasteners for construction applications. SAE (Society of Automotive Engineers) covers fasteners for automotive, machinery, and OEM applications. ASME (American Society of Mechanical Engineers) standards B18.2.1 and B18.2.1 cover dimensional tolerances for square and hex head bolts, Screws, and Nuts. Mudge Fasteners provides fasteners to these three sets of specifications (ASTM, SAE, and ASME). A fourth specification group that is also applicable is AASHTO (American Association of State Highway & Transportation Officials). AASHTO specifications are typically only called out on highway projects and many AASHTO designations can be directly converted to an ASTM equivalent.