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Fernco Large Diameter Coupling with reducer bushing and stainless steel shield joining green PVC sewer pipe to concrete pipe in a trench
 
Large diameter sewer connections

Large Diameter Couplings

A proven solution pros have relied on for decades to connect, repair and rehabilitate large diameter sewer pipe. Engineered around the measured outside diameters of your pipes, for connections standard sizes don’t cover.

 
Proven for decades Engineered to your O.D.s Non-shielded or Strong Back RC No minimum order
 
What they’re for

When a catalog size won’t fit.

Large diameter work doesn’t always line up with a catalog size. When a connection falls outside our standard line, our team can engineer a coupling around the measured outside diameter of each pipe, for repairs, alterations and rehabilitation of large diameter sewer pipe.

Custom

Built to your O.D.s

Engineered around the measured outside diameter of each pipe.

10″ wide

Dependable sealing

A wide flexible PVC body with high torque stainless steel clamps, tightened up to 120 in-lb.

6 types

Versatile connections

Clay, concrete, cast iron, ductile iron, plastic or fiberglass, with a bushing system for O.D. differences from 1¼″ to 12″.

2 versions

Shielded or not

Available non-shielded, or as a Strong Back RC shielded coupling with a stainless steel shield.

Check the standard line first.

Our standard couplings run up to 27″ nominal, for pipe up to about 33.9″ O.D., and our Strong Back HTRC corrugated pipe couplings run up to 60″. If your connection fits one of those, start there. If it doesn’t, reach out to our team about a custom coupling.

Standard Couplings finder › Strong Back HTRC corrugated couplings ›

Versions

Non-shielded or Strong Back RC shielded.

The non-shielded coupling is the right fit for many jobs. Where burial depth, soil conditions or the project spec call for added support against earth loads, settlement and shear, the Strong Back RC stainless steel shield wraps the coupling and helps keep the pipe in line against shear forces from soil compaction, shifting and settling.

  • Non-shielded. Flexible PVC with high torque stainless steel clamps, for connections without heavy earth loads.
  • Strong Back RC shielded. The stainless steel shield helps keep the pipe in line against shear forces from soil compaction, shifting and settling.

Conditions vary by region and job. Always follow the project specifications and your local codes and regulations when choosing between the two.

Unshielded flexible coupling sagging under load compared with a Strong Back RC shielded coupling holding the pipe in line
Non-shielded

The flexible PVC Large Diameter Coupling with high torque stainless steel clamps. Coupling clamps tighten to 120 in-lb.

Strong Back RC shielded

The same coupling with a stainless steel shield over the joint for added strength and support. Shield clamps tighten to 60 in-lb.

About Strong Back RC ›
Custom builds

Made to the job’s numbers.

A coupling we built to a job’s measured outside diameters, shown as a dimensional drawing and as an example of the submittal that goes with it.

Dimensional drawing of a custom 44.00 by 38.30 inch Large Diameter Coupling44.00″ × 38.30″Dimensional drawing: custom welded coupling and reducer bushingView drawing › First page of an example submittal for the 44.00 by 38.30 inch Large Diameter CouplingExample submittalTwo pages for the same 44.00″ × 38.30″ build: product data, materials, installation summary, review block and the dimensional drawingView submittal ›
How to order

Your measurements. Our engineering.

  1. Measure both pipesGet the outside diameter of each pipe. On large pipe, wrap a tape around it and divide the circumference by 3.1416.
  2. Share the detailsSend both O.D.s, the material of each pipe and the application.
  3. Our team reviews itWe review the connection and follow up on a custom coupling, and any reducer bushings, for your job. No minimum order.

Custom parts are non-refundable, so measure carefully.

Start a custom request

Installation

How it goes together.

  1. Reducer on the small pipeInstall the reducer bushing near the end of the small pipe, with the single lip away from the pipe end.
  2. Coupling over the reducerSlide the coupling over the reducer and snug the clamps to hold it in place.
  3. Insert the large pipePush the large pipe into the other end of the coupling.
  4. Tighten and inspectTighten the coupling clamps to 120 in-lb, and any shield clamps to 60 in-lb. Bed and support the pipe, then inspect and test before backfilling.

Couplings with two reducer bushings have their own install sheet, in Documents below.

Specifications.

SizesEngineered to the measured O.D. of each pipe
Part numbersLDC followed by the pipe O.D.s, for example LDC 44.00x38.30
Pipe materialsClay, concrete, cast and ductile iron, plastic or fiberglass
VersionsNon-shielded, or Strong Back RC with a stainless steel shield
BodyFlexible PVC, 10″ wide
ClampsHigh torque stainless steel with multiple take-up points
Installation torque120 in-lb on the coupling clamps. 60 in-lb on shield clamps, if supplied.
Reducer bushingsFor O.D. differences from 1¼″ to 12″
Maximum operating temperature140°F, non-continuous
Minimum operating temperature−30°F
StandardASTM D5926
OrderingNo minimum order. Custom parts are non-refundable.

Documents.

Installation instructions, an example submittal, custom build drawings and the catalog page.

Large Diameter Couplings with One BushingInstallation · PDFView instructions Large Diameter Couplings with Two BushingsInstallation · PDFView instructions 44.00 × 38.30Dimensional drawing · custom buildView drawing Example submittal: LDC 44.00 × 38.30Submittal · PDF, 2 pagesView submittal 37.00 × 32.00Dimensional drawing · custom buildView drawing Fernco Plumbing CatalogCatalog · page 18View catalog