Weld Bung Installation Guide

Speedflow Weld Bung Installation Guide - Professional Welding & Installation

Before You Install - Pre-Installation Checklist

Print this checklist and verify each item before beginning installation:

☐ Parts Verification

  • Correct weld bung type for your application (989, 990, 999 Series)
  • Correct thread size or AN size
  • Correct material (steel, stainless steel, or aluminium)
  • Matching sensor, fitting, or plug for the bung
  • All components are clean and free from debris

☐ Tools & Equipment Ready

  • TIG welder with appropriate filler rod
  • Hole saw or step drill (correct size for bung)
  • Deburring tool or file
  • Center punch and drill
  • Measuring tools (calipers, ruler)
  • Marker or scribe
  • Welding helmet, gloves, and safety equipment
  • Acetone or brake cleaner
  • Clean rags
  • Magnetic clamp or fixture (helpful but not required)

☐ Workspace Preparation

  • Well-ventilated area for welding
  • Fire extinguisher nearby
  • Clean, stable work surface
  • Tank/pan drained and cleaned (if applicable)
  • Flammable materials removed from area

☐ Safety Verification

  • Tank is completely empty and purged (if welding on fuel tank)
  • Area is free from fuel vapors
  • Proper ventilation for welding fumes
  • All safety equipment ready

Weld Bung Types & Applications

989 Series - Universal Threaded Weld Bungs

  • Applications: O2 sensors, temperature sensors, pressure sensors, drain plugs
  • Thread types: M18 x 1.5 (O2 sensors), NPT threads, metric threads
  • Materials: Steel, stainless steel, aluminium
  • Best for: Exhaust systems, oil pans, custom manifolds

990 Series - Female ORB (O-Ring Boss) Weld Bungs

  • Applications: Oil coolers, fuel rails, hydraulic systems, turbo oil feed/drain
  • Thread types: Straight threads with O-ring groove
  • Materials: Aluminium (anodized)
  • Best for: High-pressure applications, reusable connections

999 Series - Male AN Weld Bungs

  • Applications: Fuel tanks, oil pans, radiators, catch cans, dry sump systems
  • Thread types: Male AN threads (-3AN to -20AN)
  • Materials: Aluminium (anodized)
  • Best for: Custom fuel cells, oil system plumbing, coolant systems

Hole Sizing Chart

Critical: Use the correct hole size for proper fitment and weld penetration.

989 Series (Threaded Bungs)

  • M18 x 1.5 (O2 sensor): 18mm hole
  • 1/8" NPT: 11mm (7/16") hole
  • 1/4" NPT: 14mm (9/16") hole
  • 3/8" NPT: 17mm (11/16") hole
  • 1/2" NPT: 23mm (29/32") hole

990 Series (Female ORB)

  • -4 ORB: 14mm hole
  • -6 ORB: 17mm hole
  • -8 ORB: 21mm hole
  • -10 ORB: 25mm hole
  • -12 ORB: 29mm hole

999 Series (Male AN)

  • -3AN: 11mm hole
  • -4AN: 14mm hole
  • -6AN: 17mm hole
  • -8AN: 21mm hole
  • -10AN: 25mm hole
  • -12AN: 29mm hole
  • -16AN: 37mm hole

Installation Steps - TIG Welding Method

Step 1: Mark the Location

  1. Measure and mark the exact location for the weld bung
  2. Consider clearance for the sensor/fitting that will be installed
  3. Ensure adequate clearance from edges (minimum 15mm)
  4. Use center punch to mark the center point
  5. Double-check location before drilling

Step 2: Drill the Hole

  1. Use correct size hole saw or step drill (see chart above)
  2. Drill slowly to prevent work hardening the material
  3. Use cutting fluid for cleaner holes and longer tool life
  4. Ensure hole is perpendicular to the surface
  5. Check hole size with calipers

Step 3: Prepare the Surface

  1. Deburr the hole thoroughly (inside and outside)
  2. File or grind the area around the hole flat if needed
  3. Clean area with acetone or brake cleaner
  4. Remove all oils, grease, and contaminants
  5. Wipe dry with clean rag
  6. Clean the weld bung with acetone as well

Step 4: Position the Weld Bung

  1. Insert weld bung into hole from outside
  2. Ensure bung is flush with surface (or slightly recessed)
  3. Check that bung is perpendicular to surface
  4. Use magnetic clamp or fixture to hold in place (if available)
  5. Verify orientation is correct for final installation

Step 5: Tack Weld

  1. Set up TIG welder for material type (aluminium or steel)
  2. Use appropriate filler rod
  3. Place 3-4 tack welds evenly spaced around bung
  4. Allow to cool between tacks
  5. Check that bung hasn't moved or warped
  6. Re-check perpendicularity

Step 6: Complete the Weld

  1. Weld completely around the entire circumference
  2. Maintain consistent heat and travel speed
  3. Ensure full penetration without burning through
  4. For aluminium: Use AC TIG with appropriate amperage
  5. For steel: Use DC TIG with appropriate amperage
  6. Allow to cool naturally (don't quench)

Step 7: Inspect the Weld

  • Visual inspection - no cracks, porosity, or gaps
  • Weld should be continuous around entire circumference
  • No undercut or excessive buildup
  • Bung should be firmly attached with no movement
  • Clean any discoloration or oxidation

Step 8: Pressure Test (Critical for Fuel/Oil Systems)

  1. Install a plug or cap in the weld bung
  2. Pressurize system to operating pressure (or higher)
  3. Apply soapy water around weld
  4. Look for bubbles indicating leaks
  5. Hold pressure for minimum 5 minutes
  6. Re-weld if any leaks are found

TIG Welding Settings Guide

Aluminium Weld Bungs (AC TIG)

  • Material thickness 1.5-2mm: 60-80 amps
  • Material thickness 2-3mm: 80-100 amps
  • Material thickness 3-4mm: 100-130 amps
  • Filler rod: ER4043 or ER5356 (2.4mm or 3.2mm)
  • Tungsten: 2% ceriated or pure tungsten (2.4mm)
  • Gas: 100% Argon at 10-12 L/min

Steel/Stainless Weld Bungs (DC TIG)

  • Material thickness 1.5-2mm: 50-70 amps
  • Material thickness 2-3mm: 70-90 amps
  • Material thickness 3-4mm: 90-120 amps
  • Filler rod: ER70S-2 (mild steel) or ER308L (stainless)
  • Tungsten: 2% lanthanated or ceriated (2.4mm)
  • Gas: 100% Argon at 10-12 L/min

Common Installation Mistakes to Avoid

  • ❌ Wrong hole size - Too small = won't fit, too large = poor weld joint
  • ❌ Dirty surfaces - Oils and contaminants cause porosity and weak welds
  • ❌ Not deburring - Burrs prevent proper fitment and sealing
  • ❌ Insufficient penetration - Weld must penetrate through both materials
  • ❌ Welding on fuel tank with residue - EXTREME FIRE HAZARD
  • ❌ Skipping pressure test - Leaks will cause failures and safety issues
  • ❌ Wrong bung orientation - Check clearance before welding
  • ❌ Too much heat - Can warp thin materials or burn through
  • ❌ Incomplete weld - Must weld entire circumference

Special Considerations

Welding on Fuel Tanks (CRITICAL SAFETY)

  1. NEVER weld on a tank with fuel residue
  2. Drain tank completely
  3. Flush multiple times with water and detergent
  4. Steam clean if possible
  5. Purge with inert gas (argon or nitrogen)
  6. Verify no fuel vapors with gas detector
  7. Have fire extinguisher ready
  8. Work in well-ventilated area

Welding Aluminium Bungs to Aluminium Tanks

  • Material must be same alloy for best results
  • Clean thoroughly - aluminium oxidizes quickly
  • Use AC TIG with appropriate filler
  • Pre-heat may be required for thick materials
  • Allow to cool slowly to prevent cracking

Welding Steel Bungs to Steel Pans/Manifolds

  • Easier to weld than aluminium
  • Use DC TIG or MIG welding
  • Watch for warping on thin materials
  • May require post-weld cleanup/grinding

Troubleshooting

Weld bung leaks after installation:

  • Check for incomplete weld around circumference
  • Look for porosity or pinholes in weld
  • Verify full penetration was achieved
  • Re-weld problem areas after cleaning

Weld bung not perpendicular:

  • Cut out and start over (if critical)
  • May be acceptable if sensor/fitting still clears
  • Use fixture or jig for next installation

Material warped during welding:

  • Too much heat was used
  • Reduce amperage for next attempt
  • Weld in shorter segments with cooling time
  • Use heat sink or backing plate

Porosity in weld:

  • Surface wasn't clean enough
  • Contaminated filler rod
  • Insufficient gas coverage
  • Grind out and re-weld after cleaning

Post-Installation

☐ Final Checklist

  • Weld is complete around entire circumference
  • No visible cracks, porosity, or defects
  • Pressure test passed (no leaks)
  • Bung orientation is correct
  • Clearance verified for sensor/fitting installation
  • Surface cleaned of welding residue

Installing Sensors/Fittings

  • Use appropriate thread sealant (if required)
  • For NPT threads: Use Teflon tape or thread sealant
  • For ORB fittings: Use new O-ring (no sealant needed)
  • Torque to manufacturer specifications
  • Re-test for leaks after installation

Need Help?

Technical Support:
Call Scott at SS Racetech Rods & Customs
📞 0417 391 414
📧 sales@racereadygear.com.au

Shop for Weld Bungs:

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⚠️ Safety Warning: Welding on fuel tanks is extremely dangerous. If you're not experienced with this type of work, hire a professional fabricator. Your safety is more important than saving money.

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