Description
Installation Guide for Union Flexible Joints (Screw-End Rubber Expansion Joints)
By SYNTHETIC RUBBER PRODUCTS – The Largest Rubber Flexible Joint Supplier in Malaysia
The Highest Quality Union Flexible Joint Manufacturer
Union Flexible Joints, also known as Screw-End Rubber Expansion Joints, are precision-engineered components used in pipelines to absorb vibration, reduce stress, and compensate for thermal movement.
Proper installation is crucial to ensure maximum performance, leak-free sealing, and long service life.
Pre-Installation Preparation
Before starting installation in any piping system — whether in Kuala Lumpur, Penang, Johor Bahru, Kota Kinabalu, or Kuching — carefully inspect the components and site conditions.
1. Verify Product and Site Conditions
- Confirm the model, size, and material type (EPDM, Neoprene, or NBR) according to your system requirements.
- Ensure the pipe ends and union threads match correctly (BSP or NPT type).
- Check that the rubber bellows are not twisted, cracked, or deformed.
- Verify pressure and temperature ratings against actual system conditions.
(Example: standard pressure rating PN16 up to 16 bar; temperature up to 120°C depending on rubber material.)
2. Prepare Tools and Accessories
You’ll need:
- Adjustable spanners or pipe wrenches
- PTFE thread seal tape or sealing compound (for threaded unions)
- Pipe alignment tool or level gauge
- Lubricant (non-petroleum-based, for rubber protection)
- Pressure gauge for system testing
Installation Steps
Step 1: Check Pipe Alignment
- Ensure both pipeline ends are aligned and level before installation.
- Misalignment will stress the rubber bellows and shorten its lifespan.
- Use a spirit level or alignment jig to verify straightness.
Step 2: Clean the Connection Ends
- Clean both pipe threads and union ends thoroughly.
- Remove dirt, rust, and debris to avoid leaks.
Step 3: Apply Thread Sealant
- Wrap PTFE tape around the male threads in a clockwise direction (3–4 turns).
- Alternatively, apply an approved liquid thread sealant compatible with water, oil, or chemical service.
- Avoid excess sealant entering the rubber bellows.
Step 4: Install the Union Flexible Joint
- Hold the flexible joint in neutral position (not stretched or compressed).
- Align it between the two threaded pipe ends.
- Hand-tighten both union nuts first.
- Then use a wrench to tighten securely — typically 1/2 to 1 full turn after hand-tight.
Do not over-tighten — excessive torque may damage threads or compress the bellows excessively.
Step 5: Check Alignment and Neutral Position
- After tightening, ensure the rubber body is not twisted or bent.
- The joint must remain in a neutral position at system’s normal temperature.
- There should be a slight gap between the bellows and metal ends to allow movement.
Step 6: Pressure Test
- Slowly pressurize the system to half working pressure and check for leaks.
- If no leakage, raise to full working pressure.
- Observe for any deformation or movement in the bellows.
If leakage occurs, depressurize, reseal threads, and retighten unions.
Installation Tips for Best Performance
Always install in neutral condition — do not pre-compress or pre-stretch.
Support pipelines properly with hangers or anchors; the joint is not a load-bearing element.
Leave sufficient space around the joint for thermal movement and maintenance.
Never use the joint to correct pipe misalignment — use alignment fittings first.
For vertical installations, support the weight of the piping with clamps to avoid overloading the joint.
Avoid direct exposure to UV sunlight or ozone — shield with protective covers if outdoors.
Do not paint or coat the rubber body.
Post-Installation Testing and Maintenance
Initial Inspection
- After system pressurization, check for:
- Leaks at threads or unions
- Excessive bulging of rubber bellows
- Unusual vibration or noise
Routine Maintenance (Every 6–12 Months)
- Inspect rubber for aging, cracking, or deformation.
- Ensure union connections are tight and leak-free.
- Clean external surfaces to remove oil or dust.
- Rotate or replace joints if used in high-vibration environments (e.g., pumps or compressors).
Replacement Indicators
Replace the joint if:
- Cracks appear on the bellows
- Leaks persist even after tightening
- Swelling or deformation exceeds 10% of original shape
- The rubber becomes brittle due to temperature or chemical exposure
Installation Locations Across Malaysia
Our Union Flexible Joints are installed nationwide — across:
- Peninsular Malaysia: Kuala Lumpur, Selangor, Johor Bahru, Penang, Ipoh, Seremban, Melaka, Kuantan, Alor Setar, Kota Bharu, Kuala Terengganu, Kangar.
- East Malaysia: Kota Kinabalu, Sandakan, Tawau, Lahad Datu, Keningau, Kuching, Miri, Bintulu, Sibu, Limbang, and beyond.
Engineers and contractors across Malaysia trust SYNTHETIC RUBBER PRODUCTS for vibration isolation, noise reduction, and long-lasting performance in mechanical, plumbing, and marine installations.
Why Choose SYNTHETIC RUBBER PRODUCTS
The Largest Rubber Flexible Joint Supplier in Malaysia
The Highest Quality Union Flexible Joint Manufacturer
Designed for easy installation, long lifespan, and leak-free operation
Backed by nationwide technical support and ISO-certified production standards
Trusted by industries from HVAC, plumbing, marine, chemical, to public infrastructure
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