Wills Rings®

Your Partner for Sealing Technology Trelleborg Sealing Solutions is a major international sealing Facilities are certified to ISO 9001:2008 and ISO/TS 16949:2009. Trelleborg Sealing Solutions is backed by the experiences and development from our market-leading product and material resources of one of the world‘s foremost experts in polymer portfolio: a one-stop-shop providing the best in elastomer, technology: the Trelleborg Group. thermoplastic, PTFE and composite technologies for applications in aerospace, industrial and automotive industries. With 50 years of experience, Trelleborg Sealing...

Wills Rings® Latest information available at www.tss.trelleborg.com Edition November 201

Wills Rings® SEALING SOLUTIONS Latest information available at www.tss.trelleborg.com Edition November 2012

■ Introduction Trelleborg Sealing Solutions designs and manufactures a wide range of seals and bearings, which are used in many industries and applications, including Wills Rings®. Wills Rings® are the original metal O-Ring seals. First developed at the Trelleborg Sealing Solutions facility in Bridgwater, the term Wills Rings® has become synonymous with this type of seal and is internationally used as a generic term to describe metal O-Ring seals. Superior controlled compression type seals used in static applications, Wills Rings® withstand extreme conditions that exceed the capabilities of elastomer...

Wills Rings® The resistance of the ring to compression enables it to generate a sealing force when compressed. The resilient effect of the seal can be increased by pressurizing the internal volume of the ring, see Type MOT gas filled Wills Rings® O. Alternatively, if the system to be sealed is very high pressure, this system pressure can be used to provide additional sealing effect. This is called system actuation and is achieved by allowing the high pressure to enter the seal through vent holes, see Type MOV or the open C slot, Type MCX. A softer plating or coating material can be applied to...

Wills Rings® ■ Selection Table Use this table to select the optimum seal for an application. A, B, C or D indicates relative performance. Further information can be found on the relevant pages as indicated. Table 1 Selection Criteria If further information on seal selection is required please contact your local Trelleborg Sealing Solutions Marketing Company. Inconel® is a trademark of INCO Alloys International, Inc. Properties: A = Excellent B = Good C = Satisfactory D = Poor Latest information available at www.tss.trelleborg.com Edition November 2012 TRELLEBORG SEALING SOLUTIONS

Wills Rings® ■ Materials Table 2 Standard Seal Materials for Wills Rings® O Seal Material Available in a wide range of materials, Wills Rings® are used as static seals in a large number of industrial sectors. The choice of material affects the seal performance and materials should be chosen after considering the following requirements: - Pressure and temperature - Seating loads - Corrosion resistance - Compatibility with housing materials - Length of life - Sealing level - Cost Industry Standards For some industries seal material selection can be critical and require compliance with industry...

Wills Rings® The sealing capability of Wills Rings® is greatly enhanced by the addition of a softer coating material, see Figure 3. Table 4 gives the technical data for each coating, including the plating thickness, temperature capability and the size range. Select plating and coatings for applications by considering the following system requirements: 1. Level of sealing needed and the fluid to be sealed 2. Operating temperature 3. Compatibility to media Plating and Coating Materials for Wills Rings® For higher levels of sealing, more layers of plating should be combined with a better surface...

Wills Rings® ■ Hardware, Finish and Media Table 5 shows the media that can be sealed with different plating materials and the required surface finish for the housing. It is important that all machining marks are concentric with the line of seal contact. Spiral or radial marks should be avoided as these can form leak paths across the seal face. The groove should be machined to the required finish and not polished by hand. Polishing can lead to radial marks on the sealing surface which may form leak paths. Typically a thin gas is more difficult to seal than a heavy liquid, and requires a better...

Wills Rings® Wills Rings® O Type MOT (Gas Filled) The most frequently used Wills Rings® are filled with nitrogen gas. The gas pressure inside the seal rises with temperature to offset the loss of tubing strength at elevated temperatures. Advantages -- High temperature capability -- Available in a wide range of materials and finishes Wills Rings® O Type MOV Internal Pressure Type MOW External Pressure (System Pressure Actuated) These seals are ideal for extreme pressure applications. System pressure actuates the seal ring through vent holes on the seal wall. The vent holes are on the inside diameter...

Wills Rings® ■ Wills Rings® O Type MOU Non-Pressurized As these types of Wills Rings® O are filled at atmospheric pressure only, they are suitable for moderate sealing. This limits the safe maximum working temperature. ■ Wills Rings® O Type MOS Solid Solid seals exhibit virtually no elastic behavior and also have very high seating loads. Being crush seals, solid Wills Rings® O operate in a similar manner to gaskets. Advantages - Available in a wide range of materials and finishes - Resistant to corrosion, chemical attack and radiation - Long life - Cost-effective in less demanding applications...

Wills Rings® Wills Rings® C Type MCX Internal Pressure Type MCY External Pressure System pressure actuates the seal through a vent slot in the C profile which runs around the entire circumference of the seal. This slot is internal for internal pressure, and external for external pressure. A key benefit of this seal type is an increased amount of seal springback. This can be triple the amount exhibited by metal O-Ring seals. Also, by using a thin wall section, low seating loads can be achieved. Advantages -- Low seating loads -- High springback -- Good pressure and temperature capability -- Long...