Flexible Rubber Joint

QS Pipe Fitting: Ningbo Flexible Rubber Joint

A 20 inch single sphere flexible rubber joint in oil resistant NBR with a fabric reinforced body and loose metal flanges.

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One-Minute Overview

A 20 inch single sphere rubber joint in oil resistant NBR for flexible pipe connections.
Fabric reinforced rubber body paired with loose metal flanges for easy bolt-up.
Rated 150 LB and built to absorb vibration, noise and misalignment.
Sizes, pressure ratings and materials are confirmed per inquiry.

A flexible rubber joint, also called a one ball or single sphere joint, is the compliant element that lets a rigid piping system breathe. This one is moulded from nitrile butadiene rubber, or NBR, chosen for its resistance to oils, fuels and many chemicals. Fabric plies embedded in the rubber wall carry the pressure while the elastomer provides the flexibility, and loose metal flanges let the joint be bolted between pipe spools without transmitting torque to the rubber. At 20 inch and rated 150 LB, it absorbs angular, axial and lateral movement, damps vibration and noise, and compensates the small misalignments that otherwise load pumps, valves and anchors.

Name: Flexible Rubber Joint
Type: One ball, single sphere joint
Size: 20 Inch
Pressure: 150 LB
Material: NBR nitrile butadiene rubber
Construction: Fabric reinforced rubber with loose metal flanges
Feature: Absorbs vibration, noise and movement
Sizes in inches, wall schedules and end preparation are confirmed per inquiry, and a detailed specification sheet is available on request.

Start with the medium and the movement budget. NBR is the right call for oily or fuel contaminated water, but the temperature and the exact chemical should be checked before the compound is fixed, because rubber ages faster at the top of its range. Single sphere joints are compact and good at angular movement; where the thrust is high, add control rods or limit stops so the joint is not asked to carry the pressure load on its own. Match the 150 LB flange rating to the piping class, confirm the face to face length, and keep the pipe anchors and guides doing their job so the movement is absorbed by the joint rather than by the equipment. Every size, wall schedule and end type is confirmed per inquiry against the spool drawing.

Installation is where most rubber joints are won or lost. Never stretch, compress or offset the joint to close a bad pipe gap: bring the flanges to the joint at its natural length instead. Set the flanges parallel and concentric, use a gasket only where the design calls for one, and tighten bolts evenly in a cross pattern to the recommended torque. Keep sharp edges, weld spatter and fresh paint away from the rubber, recheck bolt torque after the first thermal cycle, and store spares cool, dry and out of direct sunlight so ozone does not craze the surface before the joint ever sees service.

FAQ

Q1. What does a single sphere joint do that a rigid connector cannot?

A rigid spool transfers every bit of pump vibration, thermal growth and settlement straight into the neighbouring equipment. A single sphere rubber joint flexes in axial, lateral and angular directions at once, so it isolates vibration, quiets the line and takes up small misalignments. The fabric reinforced wall holds the pressure while the elastomer does the moving, which protects pump nozzles, valve bodies and anchors from loads they were never sized for.

Q2. Can I just pull the joint to close a gap between two flanges?

Please do not. Installing a rubber joint pre stretched or compressed uses up its travel before the plant even starts, so it has nothing left for real thermal movement and the fabric plies sit under permanent load. Align and support the pipe properly, use a Spool piece or an adjustable section to close the gap, and fit the joint at its free length. A few minutes spent on fit-up buys years of service life.

Q3. Will NBR sulk if a bit of oil turns up in the line?

Quite the opposite, oil is what NBR is good at. Nitrile rubber was developed precisely to resist oils, fuels and greases that swell natural rubber, so a little hydrocarbon in the water is its comfort zone. The things to watch are high temperature, strong oxidisers and aggressive solvents, so tell us the medium and the working temperature with the inquiry and the compound can be matched to the duty.

Q4. What payment terms do you accept?

T/T, L/C at sight and other internationally accepted terms. The exact terms are agreed with you before production starts, because the payment schedule has to match the order value, the shipping method and the delivery schedule you need — which is also why we confirm them up front rather than after shipment.

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