Wills Rings® PROT I NTG T H EF OES YO U REC PATR N ER R SSEENATLI ANLG T EC H N O LO GY

Protecting the Essential Trelleborg Sealing Solutions is one of the world’s leading developers, manufacturers and suppliers of precision seals, bearings and custom-molded polymer components. We collaborate closely with customers to develop unique, innovative solutions to tomorrow’s challenges. Utilizing our dedicated product design, material development and testing capabilities, we are a one-stop-shop providing the best in elastomer, silicone, thermoplastic, PTFE and composite technologies for applications in aerospace, automotive, general industrial and healthcare & medical industries. customers...

24 Metric Part Numbers and Ordering Instructions 24 Metric Size Ranges and Free Heights 25 Metric Groove Clearance and Plating Allowances 26 Metric Part Number Systems for Wills Rings® 10 Hardware, Finish and Media 13 Compression Loads to Seat Wills Rings® 14 Calculating Seating Loads 28 Inch Part Numbers and Ordering Instructions 28 Inch Size Ranges and Free Heights 29 Inch Groove Clearance and Plating Allowances 30 Inch Part Number Systems for Wills Rings® 32 Quality Criteria 32 Storage 34 Digital Services 18 Part Numbers and Ordering Instructions in Metric 18 Installation Recommendations for...

! This page is intentionally left blank. 4 • TRELLEBORG SEALING SOLUTIONS Latest information available at www.trelleborg.com/seals • Edition April 202

■ Introduction Trelleborg Sealing Solutions designs and manufactures a wide range of seals and bearings for many industries and applications, including Wills Rings® , the original metal O-Ring seals. First developed at the Trelleborg Sealing Solutions facility in Bridgwater, UK, 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 which can withstand extreme conditions that exceed the capabilities of elastomer and polymer seals. The...

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, the pressure can be used to provide additional sealing effect. This is called system actuation and is achieved by allowing the pressure to enter the seal through vent holes (see Type MOV or the open C slot, Type MCX). Before Installation Wills Rings®are defined by their free height, which is the...

Selection Table Selection Table Use this table to select the optimum seal for an application. A, B or C indicates relative performance. Further information can be found on the relevant pages as indicated. Table 1: Selection Criteria Extreme Conditions Seating Loads Vacuum Sealing Pressure MPa/psi Max. Working Temp. °C / °F Cryogenic to Vented external Internal pressure Stainless Steel 316 L Stainless Steel 321 Inconel® 600 Silver Nickel Silver Nickel Standard Material External pressure If further information on seal selection is required please contact your local Customer Solution Center. Inconel®is...

WILLS RINGS® • Materials Available in a 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: - Seating loads - Corrosion resistance - Compatibility with housing materials - Sealing level For some industries, seal material selection can be critical and require compliance with industry standards. For example, a Wills Rings® C with compliance to NACE MR0175 should be selected in material Inconel® 718 and be hardened using treatment...

PLATING AND COATING MATERIALS FOR 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 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 3. Compatibility with media For higher levels of sealing, more layers of plating should be combined with a better surface finish. Increased plating and a better...

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. Typically a thin gas is more difficult to seal than a heavy liquid, and requires a better surface finish. The lower the media viscosity, the higher the surface finish quality and plating level required. The groove should be machined to the required finish...

Wills Rings®O W ills 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 - Resistant to corrosion, chemical attack and radiation W ills 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...

W ills Rings®C Type MCX Internal Pressure Type MCY External Pressure System pressure actuates the seal through a vent slot in the C profile that runs around the entire circumference of the seal. This slot is internal for internal pressure, and external for external pressure systems. A key benefit of this seal type is an increased amount of seal springback. This can be triple the amount exhibited by metal Wills Rings®O 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 Type MCX...