Submerged Arc Welding is valued for its efficiency and deep penetration. As well as it’s consistent results on heavy plate and structural applications. But like any welding process, it comes with its challenges. Problems such as porosity, lack of fusion, or arc instability can slow down production and increase costs. Plus, compromise weld quality if not addressed correctly.
This guide walks you through the most common SAW troubleshooting issues, their root causes, and practical fixes.
Whether you’re running a fabrication workshop, maintaining plant equipment, or producing large-scale weldments. These tips will help you get back on track quickly and keep quality under control.
Written by the Westermans Technical Team. Drawing on over 50 years of hands-on experience supplying and servicing submerged arc welders Worldwide.
Key Takeaways
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Porosity. Caused by contamination or flux issues – check material prep and flux storage.
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Lack of fusion. Caused by low heat input or poor joint prep – adjust parameters and review joint fit-up.
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Cracking. Caused by stress, cooling rate, or hydrogen – use correct preheat and consumables
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Arc instability. Caused by incorrect stick-out or travel speed – reset parameters and electrode position
Contents
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Quick Reference Table
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Diagnostic Workflow
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Common Issues – Including symptoms, likely causes, detection methods and corrective actions
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Preventative maintenance checklist
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Visual aids
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FAQs
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Further reading
1. Reference Table
A practical, scannable guide to quickly troubleshoot any issues you may be experiencing.
| Defect | What it Looks Like (Symptoms) | Likely Causes | Corrective Actions |
|---|---|---|---|
| Porosity | Small holes/voids in or on weld bead | Base metal contamination (oil, rust, paint); flux moisture; incorrect travel speed | Clean and dry base metal; rebake or replace damp flux; adjust travel speed and amperage |
| Lack of Fusion | Weld metal doesn’t bond fully with base plate; incomplete penetration | Low heat input; poor joint preparation; incorrect electrode angle | Increase amperage/voltage; improve joint geometry; adjust electrode positioning |
| Cracking | Visible or hidden cracks in weld or HAZ after cooling | High residual stress; wrong preheat/interpass temp; hydrogen contamination | Preheat to correct temperature; use low-hydrogen consumables; consider post-weld heat treatment |
| Arc Instability | Arc wanders, fluctuates, or produces uneven bead/spatter | Incorrect electrode stick-out; inconsistent flux coverage; wire feed issues | Keep stick-out within 25–50 mm; maintain flux depth of 25–50 mm; check wire feed system and replace worn parts |
| Flux Handling Issues | Inconsistent bead, porosity, slag inclusions | Mixing recovered and virgin flux incorrectly; contaminated or damp flux | Follow manufacturer guidelines on flux ratios; sieve recovered flux; store in sealed, dry containers |
2. Diagnostic Workflow
3. Common Issues in SAW
Porosity
What it looks like: Small holes or voids scattered within the weld bead, sometimes visible on the surface.
Why it happens:
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Contamination — oils, rust, or paint on the base metal.
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Flux moisture — damp flux or poor storage conditions.
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Improper parameters — too fast travel speed can trap gases before they escape.
How to fix it:
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Ensure the base material is clean and dry before welding.
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Store flux in sealed, dry containers. If moisture you suspect moisture, re-bake it per manufacturer guidance.
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Slow down travel speed slightly or adjust amperage to allow gases to escape.
Lack of Fusion
What it looks like: The weld metal sits on top of the base plate without fully bonding. Can appear sound externally but fail inspection.
Why it happens:
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Low heat input — insufficient amperage or voltage.
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Poor joint preparation — tight root gap or incorrect bevel angle.
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Incorrect electrode positioning — arc not directed at the joint sidewall.
How to fix it:
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Increase heat input by adjusting amperage/voltage.
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Re-grind or re-cut the joint for correct geometry.
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Realign electrode angle so the arc strikes both base material and filler.
Cracking
What it looks like: Cracks forming in or near the weld after cooling. Can be visible but often detected during inspection.
Why it happens:
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High residual stresses from rapid cooling.
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Incorrect preheat or inter-pass temperatures — especially on thicker sections.
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Hydrogen-induced cracking — if consumables or flux introduce moisture.
How to fix it:
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Follow recommended preheat and inter-pass temperature controls for the material.
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Use low-hydrogen consumables and maintain proper flux storage.
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Consider post-weld heat treatment to reduce stress on critical components.
Arc Instability
What it looks like: The arc wanders or fluctuates, resulting in uneven bead shape and spatter.
Why it happens:
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Incorrect electrode stick-out — too long increases resistance, too short destabilises the arc.
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Flux pile mismanagement — inconsistent coverage over the arc.
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Feeding problems — worn drive rolls or inconsistent wire feed.
How to fix it:
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Adjust electrode stick-out within recommended range (typically 25–50 mm).
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Ensure a consistent flux layer of 25–50 mm above the arc.
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Inspect wire feed system and replace worn contact tips or rolls.
Flux Handling & Storage Issues
What it looks like: Inconsistent bead appearance, porosity, or slag inclusions.
Why it happens:
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Mixing recovered flux with virgin flux in the wrong ratio.
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Using flux contaminated by dirt, oil, or scale.
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Storing flux in humid environments.
How to fix it:
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Follow manufacturer’s guidance on the percentage of recovered flux allowed.
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Always sieve recovered flux to remove fines and contaminants.
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Store flux in sealed bins with humidity control to prevent moisture pick-up.
References & Further Reading
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American Welding Society (AWS) – Welding Handbook, Volume 1: Welding Technology
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Lincoln Electric – Submerged Arc Welding Process Guide
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The Fabricator – Consumables Corner: Troubleshooting SAW Applications
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The Welding Institute – Submerged Arc Welding Process Guide
It’s important to note that sub arc welding troubleshooting may need a systematic approach. As well as collaboration with experienced welding operators.
Regular maintenance of equipment, proper flux handling, and adherence to recommended welding parameters contribute to minimising issues during the welding process.
Additionally, referring to the manufacturer’s guidelines for specific equipment and flux recommendations is essential for successful sub arc welding troubleshooting.
If you are looking to upgrade or buy sub arc welding equipment, we can offer advice and a choice of equipment. Like we did for this UK heavy fabrication company:
Responsive Engineering quoted “The ESAB submerged arc welding system attached to the Bode column and boom manipulator, has allowed us to carry out high deposition rate welding during the latter part of jetty construction sections, increasing our skill levels in the process whilst rapidly recouping its initial cost,”
Learn more in the Case Study.
About the Author
Written by the Westermans Technical Team
Applying over 50 years of supplying refurbished welding and cutting equipment Worldwide. Our team has worked hands-on with submerged arc welders from leading manufacturers including ESAB, Lincoln Electric, and Miller. From troubleshooting in fabrication shops to advising global clients on equipment. Our engineers bring real-world experience that goes beyond the manuals.
This article draws directly on that experience to give you actionable advice, grounded in industry best practice. So you can confidently resolve issues and prevent them from happening again.
