Knowledge Series: Expansion Joint
Accessories
Retaining Rings, Control/Limit Rods, Spray Shields and Covers
DISCLAIMER
While the FSA makes every reasonable attempt to ensure that the information contained in this document is accurate and curren t, the FSA, its officers, directors, volunteers, and authorized agents are not responsible for any errors or omissions contained therein nor are they responsible for any results obtained from the use of or reliance upon its content. All information is provided “AS IS,” with no guarantee of completeness, accuracy, timeliness or of the results obtained, and without warranty of any kind, express or impl ied. In no event shall FSA or its officers, directors, volunteers, or authorized agents be liable to you or anyone else for any decision made or action taken in reliance on the information contained herein or for any for any consequential, indirect, special, or similar damages, even if advised of the possibility of such damages. The information contained in this document is for informational purposes only and does not constitute professional advice. It also includes references to certain standards that may change over time and should be interpreted only in light of particular circumstances. It is your sole responsibility to confirm the current state of any referred to standards. FSA reserves the right to modify or update the document content and to modify this Disclaimer at any time, effective upon posting of an up dated version of this Disclaimer.
© (April, 2023), Fluid Sealing Association. All Rights Reserved.
Retaining Rings
• Retaining Rings are made of various types of metals with a variety of coatings.
• The Retaining Rings shown here are the most standard type used; 3/8” Thick, A-36 Steel with a Galvanized Coating.
Functions for: Retaining Rings
• Split Metal Retaining Rings must be used to distribute the bolting load and assure a pressure tight seal. They are coated for corrosion resistance and drilled as specified.
• The rings are installed directly against the back of the flanges of the expansion joint and bolted through the mating flanges of the pipe.
• Steel washers are recommended under the bolt heads against the retaining rings; at a minimum at the splits in the rings.
• The ring I.D. edge installed next to the rubber flange should be broken or beveled to prevent cutting of the rubber.
Control / Limit Rods
• Control / Limit Rods
• Internal Tie Rod (ITR) Assembly
Functions for: Control / Limit rods
• Control / Limit Rods are used to control the axial movements of the expansion joint during normal operation.
• In the event of an anchor failure, they are designed to prevent over-extension or overcompression while absorbing the static pressure thrust at the expansion joint, generated by the anchor failure.
• Spray/Protective Shields:
• Protective Covers:
Functions for: Protective Shields & Covers
• Unusual applications of rubber expansion joints may require the specification of: Protective Shield, Protective Cover , Fire Cover.
• These three types of covers, when manufactured of metal, have one end which is bolted to or clamped to the mating pipe flange. The other end is free, designed to handle the movements of the expansion joint. A Protective Cover of metal is required when an expansion joint is installed underground.
• Protective Shields should be used on expansion joints in lines that carry high temperature or corrosive media. This shield will protect personnel or adjacent equipment in the event of leakage or splash.
• Wrap around Protective Shield of Fluoroplastic impregnated fiberglass are the most common.
• Fire Covers, designed oversize, are insulated on the I.D. to protect the expansion joint from rupture during a flash fire.
Expansion Joint Accessories
For additional technical information regarding expansion joint accessories consult the Fluid Sealing Associations Technical Handbook for Expansion Joints Piping (https://www.fluidsealing.com/)
