Knowledge Series - Chapter 6 Expansion Joint Accessories

Knowledge Series: Expansion Joint Accessories Retaining Rings, Control/Limit Rods, Spray Shields and Covers

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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

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• 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 and Covers • Spray/Protective Shields:

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• 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/)