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Shielded flexible couplings
1000 Series
Fernco flexible sealing with a stainless steel shear ring, built for underground pipe transitions that face heavy earth loads and pipe movement.
Strong Back RC combines Fernco flexible sealing performance with stainless steel reinforcement for a stronger buried transition.
Resists heavy earth loads and shear forces in demanding underground applications.
A .012" stainless steel shear ring and molded-in bushing add stability to the joint.
Connects clay, cast iron, plastic, concrete, ductile iron and steel underground piping.
Strong Back RC couplings are designed for pipe transitions where the outside diameters, pipe materials or jobsite conditions call for added alignment support. The molded-in bushing works with the stainless steel shear ring to keep the connection stable while the flexible elastomeric sleeve conforms to the pipe for a dependable seal.
Stainless steel clamps provide uniform compression, and the shear ring carries shear load so the joint holds alignment under backfill and settling.
Why shielded
Buried couplings face earth loads, settlement and shear. An unshielded flexible coupling can deform and let the pipe pull out of line. The Strong Back RC stainless steel shear ring wraps the sleeve and keeps the joint rigid and aligned, so the connection holds where it is hardest to reach.
Unshielded
Deforms and shifts under load
Shielded RC
Shear ring holds the line
| Standards | ASTM C1173, CSA B602 |
| Installation torque | 60 in-lb (120 on 16" and larger) |
| Maximum test pressure | 4.3 psi (29.6 kPa) |
| Max operating temp | 140°F non-continuous |
| Standards | CSA B602, ASTM D5926, C1173 |
| Hardness | Shore "A" 65 ±5 |
| Tensile strength | 1000 psi min |
| Elongation | 250% min |
| Brittleness | -40° F |
| Housing | 301 stainless steel |
| Band | 301 stainless steel |
| Screw | 305 stainless steel |
| Material | 300 series stainless steel |
| Thickness | .012" |
| Widths | 1.50", 2.13", 4" |
1000 Series Strong Back RC couplings 15" and below are made in the USA and meet the American Iron and Steel and Build America, Buy America requirements for federally funded underground infrastructure.
Browse the 1000 Series pairings, or use the size finder to match the two pipes you are connecting.
| Series | Connection | Drawings |
|---|---|---|
| 1001 | Clay to Clay | Drawings › |
| 1002 | Clay to Cast Iron / Plastic / Steel | Drawings › |
| 1003 | Clay to Ductile Iron | Drawings › |
| 1004 | Concrete to Concrete | Drawings › |
| 1005 | Concrete to Clay | Drawings › |
| 1006 | Concrete to Cast Iron / Plastic / Steel | Drawings › |
| 1051 | Ductile Iron to Cast Iron / Plastic / Steel | Drawings › |
| 1055 | Ductile Iron to Ductile Iron | Drawings › |
| 1056 | Cast Iron / Plastic / Steel to Cast Iron / Plastic / Steel | Drawings › |
| 1057 | Concrete to Ductile Iron | Drawings › |
| HTRC | Corrugated polyethylene to corrugated, plastic or cast iron · high torque, 10"–60" | Drawings › |
Pick the material and size of the pipe on each side. The finder returns every Fernco coupling that fits both pipe outside diameters, showing the Strong Back RC and HULK couplings that fit. Plastic and steel use Schedule 40 (IPS) outside diameters.
Recommendations are a general guide based on typical use. Coupling suitability depends on the pipe materials, application and burial conditions. Always confirm the coupling and its installation meet your local plumbing and building codes before installing.
XL RC
Strong Back XL RC couplings are available 12″ and below. They fit the same pipe outside diameters as the matching 1000 RC size, but the extra length and additional clamp bands grip more pipe for greater holding power in demanding underground joints. Sizes that offer an XL version are flagged “Also in XL” in the results above.
Dimensional drawings
Open the full Strong Back RC drawing library for the outside-diameter ranges, inch and millimeter dimensions, and a downloadable PDF for each size.
Installation instructions, submittals and catalogs for Strong Back RC.
All part numbers
Open any part for its specs, dimensional drawing and documents.
No part number matches.
Selection, installation and compliance answers for Strong Back RC.
A Strong Back RC coupling is a Fernco shielded flexible coupling with a stainless steel shear ring and a molded-in bushing added to the flexible body. The shear ring resists the earth loads and pipe movement found in buried service, while the flexible sleeve and stainless steel clamps make a sealed transition between two pipes of different material or outside diameter.
Use a Strong Back RC for below-ground transitions that carry heavy earth loads or where the pipes may shift, settle or misalign. For above-ground work, a Standard Coupling handles lighter-duty joints, and a Proflex shielded coupling adds a stainless steel shield for transitions that need extra support above grade. All three seal the same way; the shielded couplings add reinforcement for their conditions.
Both are Strong Back RC shielded couplings with a stainless steel shield. The 1000 Series uses a worm-gear stainless steel band clamp and, 15 inches and smaller, is made in the USA and AIS/BABA compliant. The 5000 Series uses a 316 stainless steel nut-and-bolt clamp for larger-diameter connections and is not AIS or BABA compliant.
The Strong Back RC line connects clay, cast iron, plastic, steel, concrete and ductile iron pipe, in same-material and transition joints. The series sets the material pairing, for example the 1002 Series connects clay to cast iron, plastic or steel, and the 1056 Series connects cast iron, plastic or steel to cast iron, plastic or steel.
Tighten the clamps to 60 inch-pounds. Couplings 16 inches and larger ship with high torque bands and are tightened to 120 inch-pounds. Pressure test the joint before backfilling or concealing it. Follow the current Fernco installation instructions for the specific coupling.
Strong Back RC couplings are manufactured to conform to ASTM C1173 and CSA B602 performance requirements, and the gasket meets ASTM D5926, ASTM C1173 and CSA B602. Listings by series are on the Codes and Standards page. Always confirm the application with your local plumbing code.
1000 Series Strong Back RC couplings 15 inches and smaller are made in the USA and comply with the American Iron and Steel (AIS) and Build America, Buy America (BABA) requirements, which supports federally funded underground infrastructure work. The 5000 Series is not AIS or BABA compliant. See the AIS and BABA page for the letter and the compliant product list.
Use the size finder on this page: choose the material and size of the pipe on each side of the joint. Fernco couplings seal by outside diameter, so the finder returns every Strong Back RC coupling whose ends accept both of your pipe outside diameters, then links you to the drawing and dimensions for each match. If you are unsure of a pipe outside diameter, measure it and compare it to the ranges shown.
Give us the pipe materials and sizes on each side and our team will point you to the right Fernco coupling.