Boiler Tube Leaks – What is the Cause? Top 5 Reasons and More

by Nicholas Piskura

Is Your Boiler Leaking? Here’s What You Need to Know

Boiler tube leaks show up more often than most teams expect, and they don’t stay small for long. Left to run, a tiny weep turns into lost heat, higher fuel bills, nuisance alarms—and in the worst case, an unplanned shutdown. Catch it early, pair good water treatment with routine checks, and you avoid the ugly repair costs and keep output steady.

Found a Leaking Tube? Act Now

Treat any leak as urgent. Even a fine spray knocks pressure off, wastes energy, and chews at the metal over time.
In many cases the leak isn’t the core problem—it’s the symptom of something upstream: oxygen getting in, pH drifting low, scale building on hot surfaces, or a gap in the treatment routine.

ChemREADY helps sites close those gaps with treatment plans that target corrosion, scale, and thermal stress—so tubes last and boilers run clean.

The Five Usual Suspects

1. Tube corrosion
2. Unified (system-wide) corrosion
3. Scale build-up
4. Thermal shock
5. Poor or inconsistent water treatment

Understand these, fold prevention into daily and weekly tasks, and tube life stretches out instead of shortening. Plant managers and engineers plan the right treatment so their boilers stay online. Learn more about Boiler Water Treatment Preventative Maintenance BMP’s

1) Tube Corrosion — the number one cause

Most tube failures start with oxygen pitting. Dissolved oxygen meets hot steel, digs small, sharp pits, and those pits grow until the wall gives way.

How to cut it off at the source:

1. Run hotter feedwater to strip out oxygen before it hits the boiler.
2. Dose an oxygen scavenger such as ChemREADY’s Boiler Deoxy (sulphite/bisulphite based) to mop up what’s left.
3. Keep a simple monitoring loop: dissolved oxygen, iron, pH, alkalinity—adjust fast when numbers move.

2) Unified Unit Corrosion — when low pH bites everywhere

This isn’t a local spot; it’s general attack across the boiler, feed, and condensate lines. Low pH speeds metal loss, and once it starts, it rarely slows on its own.

Why pH control matters

1. Below pH 8, corrosion rates climb.
2. Even pH 7 is risky; small swings push the system acidic.

What to do

1. Hold boiler water above pH 10 for dependable protection.
2. Use conditioners such as ChemREADY’s Boiler pH to set and stabilise levels.
3. Verify with frequent checks and simple trend charts.

3) Boiler Scale — the hidden efficiency drain

Scale acts like a blanket on heat-transfer surfaces. Burners work harder to hit the same load, valves start sticking, and safety relief paths can choke—none of which you want.

Keep scale from taking hold:

1. Use softening and inhibitors (e.g., BOILER DESCALE) to keep hardness in solution.
2. Stick to a blowdown schedule that actually matches your load.
3. Check make-up water and resin performance so you’re not feeding the problem.

4) Thermal Shock — cracks born from sudden change

Cold feedwater into a hot shell or tubes makes the metal expand and contract in a snap.
That cycling opens up fine cracks that turn into leaks.

Reduce the stress

1. Preheat feedwater into the recommended range before entry.
2. Keep operating temperatures steady and avoid sharp load swings.
3. Make sure control valves and feed systems ramp smoothly, not in jumps.

5) Inadequate Water Treatment — the costliest mistake

Skipping post-install treatment or easing off once things look “stable” is a quick route to early failure.

What untreated water costs

1. Faster corrosion and tube replacements.
2. More maintenance thanks to scale and fouling.
3. Lower efficiency and a higher fuel bill.

Put a proper programme in place

1. Enrol in ChemREADY’s Boiler Water Treatment Programme for long-term protection.
2. Test on a schedule and act on the data, not gut feel.
3. Align dosing and blowdown with actual solids and seasonal shifts.

The ChemREADY Advantage

• Site surveys to map risks and needs
• Total Service Management for ongoing optimisation
• Supervisory programmes with or without chemicals
• Custom solutions for commercial and industrial plants

FAQs

1) What usually causes boiler tube leaks?
Most cases trace back to oxygen pitting, low-pH corrosion, scale deposits, thermal shock, or inconsistent treatment and monitoring.

2) How do we slow or stop corrosion?
Raise feedwater temperature, use an oxygen scavenger such as Boiler Deoxy, hold boiler pH above 10, and keep a tight eye on key readings.

3) What’s the practical way to remove scale?
Dose BOILER DESCALE, keep a sensible blowdown routine, and manage hardness at the front end so deposits don’t return.

About The Author

Nick Piskura is the Marketing and Web Development Specialist at ChemREADY who utilizes expertise in digital marketing strategies to provide knowledgeable insights in each segment of our business. Nick provides insights through web development and multimedia resources that support ChemREADY’s full range of services, including Legionella management, ANSI/AAMI ST108 compliance, boiler and cooling tower treatment, wastewater processing, and industrial water quality solutions.

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