Valves are indispensable components in the hygienically sensitive systems used in the food, beverage and pharmaceutical industries. Until now, there were no high-pressure valves available for food-product contact applications that conformed to 3-A® standards. These global hygiene standards address the design and manufacturing of components that come into contact with food.

Bardiani Valvole approached Gallagher's partner, Freudenberg Sealing Technologies, for help in developing a solution to tap into its material expertise. As a result of joint cooperation, Freudenberg engineers developed a main rod seal that was both 3-A® compliant and capable of handling high-pressure of up to 2175 psi (150 bar) that the customer’s valve required. The main rod seal incorporates proven Freudenberg technology with advanced component design in an entirely new combination that is also compatible with other industrial high-pressure valves.

Prototypes produced without any tools

The 3-A® compliant main rod seal combines a sealing lip, manufactured from EPDM 302 or Fluoroprene® XP 43, with a backup ring made of PTFE. Freudenberg’s product engineers were inspired by the design of a proven shaft seal and an O-ring with a backup ring. In order to meet development and cost deadlines, the team initially produced one-off prototypes to share with Bardiani Valvole using the unique capabilities of Freudenberg Xpress®, a fast turnaround, high-quality manufacturing service that can generate custom seals in as little as a day. It offers machined seals made of original materials and original profiles for prototypes, spare parts or economical small series.

By eliminating the need to set up manufacturing tooling to produce sample parts, this results in considerable cost and time advantages for the customer. Thanks to special turning and milling techniques, individual designs can be tuned to exact specifications. The tailor-made sealing solution for the new high-pressure valve could also be produced economically in an extremely short time. The Freudenberg Xpress® Service is represented at numerous Freudenberg sites worldwide, enabling rapid delivery of spare parts, for example.

The seal’s design is free of dead space and prevents residue infiltration from process and cleaning media. It is hygienic, easier to clean, and compliant with all relevant material specifications for food, beverage, and pharmaceutical industry applications. Both materials used have very good thermal resistance and excellent mechanical properties. They also meet the demanding requirements for use in Cleaning in Place and Sterilization in Place (CIP/SIP) processes.

Freudenberg Sealing Technologies has launched series production of a modular sealing unit that combines a classic radial shaft seal with a plastic outer case. The design promotes better long-term seal performance and longevity, is easier to assemble, and significantly lowers manufacturing costs in comparison with traditional metal-encased radial shaft seal units. Freudenberg has developed the innovative sealing concept for use in general industry applications that are especially focused on small, electric household appliances.

Whether it’s to knead bread dough, mix a cake batter, puree soup ingredients or blend a smoothie, most people reach for an electric kitchen appliance to get the job done. The durability of the appliance depends largely on how well the seal at the outlet point of the drive shaft protects the interior from ingress of food residue or liquids. Seals made of high-quality elastomers or the polymer polytetrafluoroethylene (PTFE) combine low wear with excellent long-term resistance against leakage. In the past, a metal case was the best option available to maintain the integrity of the seal’s performance over a long period of time. Freudenberg Sealing Technologies has now succeeded in developing a modular sealing concept with a plastic case that meets the specific requirements for long-term performance as well as those made of metal. There are three major advantages to the new design: Significantly, in the price-sensitive, small appliance industry, the lower production costs associated with forming enclosures from plastic is an important consideration. In addition, Freudenberg's modular sealing unit concept accommodates the integration of additional components, such as shaft bearings. Finally, because small appliance housings are typically made from plastic, fastening the seal case to the appliance housing is easier to achieve.

The term “plastics” is generic way of describing a synthetic material made from a wide range of organic polymers. Organic polymers describes a man-made substance that is formulated using polymer chains to create what we commonly refer to as…(you guessed it), plastics.

Before plastic, leather had been used to create Backup ring devices behind O-rings. Leather allows fluids to be retained, providing lubrication for the O-ring when the system was running dry.

The problem with leather was that it could become dry and shrink away from the sealing service, exposing the elastomer to same pressure it was intended to protect against.

With the advent of polymers, a piece of plastic could be cut or formed into the exact shape to allow for zero extrusion gap, and for continued protection for the O-ring.

Some polymers were very brittle. Since they needed to be deformed to allow for installation into solid glands, the cut of the plastic could nibble at the O-ring, causing premature failure of the element it was supposed to be protecting.

The Revolution of PTFE

When PTFE moved out of the lab and into industrial use, it quickly found itself adjacent to the O-ring. PTFE offers extrusion resistance and, at the same time, doesn’t erode or nibble at the O-ring due to the “softness” of the polymer.(Hardness between 55 and 65 Shore D)

Given the composition of PTFE, or Teflon, it could be utilized as a sealing element to protect Backup rings and conform to the shaft. The bonus was it was generally easy on shafts (depending on the filler added to the PTFE).

There are some negative aspects to Teflon that needed to be overcome by early engineers. First, it has a fairly high rate of Thermal expansion which, by its own nature, could often times lose contact with the sealing surface. This meant some kind of loading was necessary to ensure contact.

PTFE is as tough as other polymers, so the fact that it could seal on a shaft made it vulnerable during installation for tears or nicks on sealing surface.

Second, if it were stretched during installation, the material had to be sized back to its original shape due to its poor elastic properties.

Bacteria accumulation can ruin product and put consumer health at risk.

The search for the ideal Polytetrafluoroethylene (PTFE) gasket has been elusive. Competing applications and workplace variables have led to the creation of myriad solutions, yet none that has proven fully adaptable and appropriate for universal adoption.

Garlock Sealing Technologies considered this to be a critical yet entirely solvable shortcoming. And it is against this backdrop that in 2016, they set out to compile a comprehensive list of attributes for the ideal PTFE gasket — a wish list, as it were — in order to build a better gasket.

Working with a third-party survey development company, Garlock developed an exhaustive questionnaire that probed every aspect and functionality of PTFE gaskets, testing and adjusting the questions until they had a workable, finalized version.

Using this final questionnaire, Garlock conducted extensive interviews at 15 major chemical processor companies, speaking with 20 engineers responsible for process operations, projects, maintenance and reliability. The goal was simple: to discover the ideal characteristics and their relative importance that engineers sought in a PTFE gasket.

After several months of data collection, Garlock analyzed the feedback and noted the most popular responses:

• 28% of respondents said that they struggled with how different gaskets required different compressive loads and how to ensure that those gaskets had been installed properly
• 21% expressed frustration with the creep properties of PTFE gaskets
• 21% desired a gasket that seals with less compressive load
• 14% expressed frustration at the installation inconsistencies of their fitters
• 14% expressed frustration with leaking, especially after a successful installation and start-up

From those answers, Garlock drew the following conclusions, representing the most desirable and essential PTFE gasket characteristics:

• Seal: Seals easily
• Installation and assembly: Forgiving of poor installation or assembly practices
• Forgiving: Forgiving of poor flange conditions
• Retention: Maintains a seal after installation
• Flexible: Can be used in a broad range of services to avoid user confusion and reduce inventory

Introducing: GYLON EPIX

Garlock used this feedback in developing a next generation PTFE gasket — GYLON EPIX. Featuring a hexagonal surface profile, GYLON EPIX offers superior compressibility and sealing for use in chemical processing environments. Its enhanced surface profile performs as well or better than existing 1/16″ or 1/8″ gaskets, allowing end-users and distributors to consolidate inventory, lower the risk of using incorrect gasket thicknesses and reduce stocking costs.

GYLON EPIX checks off the most desirable gasket attributes:

• Installation and assembly: Even distribution of the bolt load over the contacted area of the gasket during the assembly process
• Retention: Retention of the bolt load administered at assembly
• Seal: Efficient translation of bolt load to sealing performance
• Forgiving: The ability to perform in imperfect flanges and installation conditions

GYLON EPIX with its raised, hexagonal profile allows it to perform the job of both traditional 1/16” and 1/8” gaskets. It accomplishes this by combining the bolt retention of the former with the forgiveness for bad flange conditions of the latter, a truly innovative feature for PTFE sheet gasketing.