Readirope®
Frederickseal Technical Bulletin #4
Readirope® joint sealant is a revolutionary way to contain gases and liquids within a system to to keep them out (vacuum). This unique form of Polytetrafluoroethylene is known as EXPANDED FIBER PTFE. The "marshmallowy" consistency raises serious doubts among many professional maintenance people as to Readirope®'s abililty to replace customary gaskets on the multitude of flanged applications they are required to seal. Improper use has sustained some of their initial apprehension.

An examination of the facts and an understanding of the physics involved will erase any skepticism you may have about Readirope® joint sealant. Let us examine each factor which could impact successful sealing with Readirope®:
1. Flange Condition: While flange flatness is very critical, flange smoothness is much less important. Readirope® size selection is determined by surface irregularity. The deeper the pits, corrosion, erosion, or wire-drawing (steam) of the flange surface, the larger the size Readirope® which should be used.
2. Size of Opening: One need not consider the size of the opening. Simply make a complete circle by crossing the ends and you will achieve a seal. The width of the flanged surface is not a factor in deciding which size Readirope® to use, because it is like an o-ring—a single impenetrable line is the best seal.
3. Temperature Limits: PTFE begins to sublimate at about 550 degrees F and accelerates as the temperature rises. One should never use a PTFE product of any kind above 600 degrees F. In use, containment performance of PTFE products generally are inverse to temperature (i.e. as temperature rises the pressure containment capabilities diminish).
4. How Does Readirope® Really Work? A quick Physics lesson will reveal the answer:

A) Pascal's Principle: Henri Pascal, the French scientist, discovered relationships between forces and fluids which became known as "Pascal's Principle" or "Pascal's Law." Simply stated, Pascal's Law says: "A force placed on a confined fluid is transmitted undiminished throughout." Therefore, if we squeeze hydraulic fluid with a pump, the system pressure is consistant throughout the entire system. Anywhere one might measure system pressure with a gauge, he or she would find that system pressure is consistant throughout.

B) Obeys the Laws of a Fluid: Readirope® is a solid . . . but it is so soft that it obeys the laws of a fluid. Therefore, when a person places a "string" of Readirope® on two irregular surfaces (under a microscope, a newly-machined surface reveals irregularities) and clamps them together with the maximum recommended force (i.e. 70% of bolt yield strength), we see our "marshmallowy" Readirope® "flow" like a liquid to hydraulically load these irregular surfaces. That is, there is equal pressure along the entire surface of both flanges.

C) Another Law of Physics Completes the Picture: One of the Laws of Physics states that a force acting on a surface is equal to the product of the pressure times the surface exposed to the pressure. For example: A pipe with 500 PSI of pressure within it is sealed at a flange with a 1/8" thick compressed gasket material. The force trying to blow the gasket out would be 500 PSI x 1/8", and the tensile strength of the gasket would hold the pressure back. NOW, if we double the gasket thickness to 1/4", we also double the force trying to blow out the gasket, but we do not double the gasket's tensile strength. Therefore, as the gasket got thicker and thicker, the force would continue to grow relative to the tensile strength of the gasket and eventually blow out the gasket.

D) Readirope® Draws Flanges Down to ZERO: Returning to our Readirope® scenario, let's consider the Physics of the situation: 500 PSI x 0 = ?

RIGHT! ZERO!

This is why we can hold back thousands of PSI in hydraulic force with this "marshmallowy" product.
5. How to Choose a Size: Surface irregularity is the single determining factor! The surface must be FLAT and CLEAN but can be very rough. The rougher the surface, the larger the Readirope® size required because more volume is needed to fill deep crevices. Bolting load, which determines seating stress, is very important. The larger Readirope® size you choose, the more bolting load you must have to achieve "ZERO" clearance.

USE THE SMALLEST SIZE READIROPE® YOU DARE TO USE RELATIVE TO THE SURFACE IRREGULARITIES.

PRACTICE ON LESS CRITICAL APPLICATIONS UNTIL YOUR EXPERIENCE GIVES YOU INCREASING CONFIDENCE IN YOUR ABILITY TO SELECT THE RIGHT SIZE.

REMEMBER: THE SMALLER THE READIROPE® SIZE, THE LOWER THE GASKET COST.
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