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🧰 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