⚓ THE BUNKER WAS “WITHIN SPEC” — SO WHY DID THE PURIFIERS FAIL?

 

⚓ THE BUNKER WAS “WITHIN SPEC” — SO WHY DID THE PURIFIERS FAIL?

When bunker quality becomes a dispute, the real battle is not between one laboratory report and another. It is about evidence, causation, operational suitability and how quickly the ship protects its position.

The bunker report arrives.

The numbers appear acceptable.

The fuel is not classified as clearly off-spec.

The vessel continues consuming it.

Then something changes.

The purifier begins tripping.

Breakdowns become more frequent.

Sludge or deposits appear.

The engineering team spends increasing time cleaning, monitoring and troubleshooting.

And suddenly, a seemingly simple question becomes a serious commercial issue:

If the fuel meets the numerical specification, why is the vessel experiencing operational problems?

That question sits at the heart of many bunker disputes.

And it teaches a lesson that extends far beyond fuel:

Compliance with a number is not always the same thing as operational suitability.

 

THE FIRST TRAP: “WITHIN SPEC” DOES NOT END THE DISCUSSION

When Charterers say:

“The highlighted parameters are within the applicable ISO specification.”

the statement may answer one question.

But it may not answer every question.

A fuel analysis tells us what was found in the sample and whether particular parameters fall within specified limits.

The vessel, however, tells us what happened when the fuel was actually used.

That creates two separate questions:

Question 1

Does the fuel meet the applicable numerical specification?

Question 2

Is the fuel of suitable quality for safe and reliable use in this vessel's engines and auxiliaries?

These questions should not automatically be treated as identical.

A professional investigation must examine both.

Practical takeaway

Never close a bunker investigation simply because one report says “within specification.” Compare the laboratory result with actual vessel performance.

 

WHEN THE PURIFIER STARTS TALKING

The purifier may become the first practical warning that something is not behaving as expected.

Repeated:

• purifier trips;
• purifier breakdowns;
• excessive deposits;
• sludge formation;
• filter loading; or
• abnormal fuel-system behaviour

should trigger investigation.

But there is an important distinction.

A purifier problem does not automatically prove that the bunker caused the problem.

It is an observation.

The professional task is to establish the connection.

That requires a chain:

Fuel received

↓

Fuel changeover

↓

Purifier behaviour

↓

Physical evidence

↓

Laboratory results

↓

Technical analysis

↓

Cause

This is where operational discipline becomes claims prevention.

Practical takeaway

Do not turn a symptom into a conclusion. Build the technical chain first.

 

WHAT COULD BE BEHIND THE PROBLEM?

A good investigation should not begin with one predetermined answer.

Several possibilities may need to be examined.

1. Aluminium + Silicon

Al+Si can be associated with abrasive catalytic fines.

The question is not simply:

“Is Al+Si present?”

The question is:

Could the reported level and the vessel's operating experience explain the observed problems and create an engine risk?

2. TAN / Acidity

Total Acid Number may require closer investigation where abnormal deposits, corrosion or other fuel-system concerns are observed.

Again, the objective is not to make an assumption.

It is to establish whether the reported result is consistent with what happened onboard.

3. Stability or Compatibility

The new bunker may also need to be assessed in relation to the fuel that was already onboard.

This is particularly relevant where fuels have been mixed or come into contact within the vessel's fuel system.

The investigation should therefore establish:

• What fuel was onboard previously?
• When was the changeover made?
• Which tanks were involved?
• Was residual fuel present?
• What was the condition of the receiving tanks?
• When did the abnormal behaviour first appear?

Practical takeaway

The fuel being investigated is not always the only fuel that matters. Understand what was already in the system.

 

4. Chemical Contamination

Where the standard analysis does not explain the operational symptoms, the chemist may consider whether additional chemical contamination requires investigation.

The source material specifically identifies possibilities such as certain phenolic compounds, cashew-nut-shell-liquid-related components and shale-oil components.

These are investigative possibilities—not conclusions.

Where justified, specialised testing such as GCMS may be considered by the appointed expert.

Practical takeaway

Use deeper testing when the operational evidence cannot be explained adequately by routine analysis—not simply because a dispute exists.

 

THE MOST IMPORTANT QUESTION: WHICH SAMPLE?

This is where many bunker investigations can become complicated.

Everyone may agree:

“Let's test the fuel.”

But the next question should be:

“Which fuel sample?”

Is the retained sample representative?

Was it properly taken?

Was it correctly sealed?

Has it been stored appropriately?

Does it represent the fuel actually consumed?

If a tank sample is proposed, was the sampling procedure properly agreed?

These questions matter because a technically perfect laboratory test is of limited value if the sample itself is challenged.

 

DON'T LET THE SAMPLE BECOME THE DISPUTE

Before joint testing with Charterers, the parties should ideally establish:

• the sample to be tested;
• sampling location;
• sampling procedure;
• sample identification;
• sealing arrangements;
• chain of custody;
• laboratory;
• test parameters;
• witnessing arrangements.

The purpose is simple:

Make sure both sides are testing the same question using a properly controlled sample.

Otherwise the dispute can shift from:

“What is wrong with the fuel?”

to:

“Your sample is not representative.”

That is a very expensive detour.

Practical takeaway

Agree the testing architecture before arguing about the test result.

 

THE PURIFIER PHOTOGRAPH MAY BE MORE IMPORTANT THAN YOU THINK

Photographs of a purifier during overhaul may appear to be routine maintenance records.

In a bunker dispute, they can become evidence.

A competent chemist may want to examine:

• the nature of deposits;
• sludge characteristics;
• signs of abrasion;
• unusual contamination;
• physical condition of components.

The photograph alone may not establish causation.

But together with:

FOBAS report + engine records + fuel samples + physical deposits

it can contribute to a much stronger technical picture.

Practical takeaway

Photograph abnormal conditions before cleaning or dismantling removes the evidence.

 

PRESERVE THE SLUDGE

This is easy to overlook.

Once the purifier has been cleaned, the natural operational instinct is to dispose of the sludge.

But if the material may be relevant to a technical investigation, disposal may destroy potentially useful evidence.

Where the Club, lawyers or chemist consider it appropriate, preserve representative samples of:

• sludge;
• deposits;
• filter material;
• other unusual solids removed during maintenance.

The chemist may want to analyse the contaminant itself, not only the bunker.

Practical takeaway

Before disposing of unusual material, ask whether it may be evidence.

 

BUILD THE BEFORE-AND-AFTER PICTURE

One of the strongest ways to investigate a bunker problem is to compare vessel performance before and after the fuel change.

Look at:

Before

What was normal?

• purifier performance;
• exhaust temperatures;
• scavenge conditions;
• turbocharger behaviour;
• cylinder oil feed;
• lube-oil condition;
• filter performance.

After

What changed?

• purifier trips;
• deposits;
• filter differential pressure;
• engine parameters;
• sludge generation;
• maintenance frequency.

This does not automatically establish causation.

But it creates a timeline.

And a timeline helps the expert understand the event.

Practical takeaway

Record changes against time. “What changed, and when?” is one of the most valuable questions in an investigation.

 

THE ENGINE ROOM IS BUILDING THE CLAIM

The Chief Engineer may think:

“My job is to keep the machinery running.”

In a serious bunker incident, the role is broader.

The engine-room team is also creating the technical record that may later be reviewed by:

• Owners;
• Charterers;
• P&I Club;
• lawyers;
• surveyors;
• fuel chemists;
• laboratories.

Therefore, records should be factual and contemporaneous.

Not:

“Fuel is bad.”

But:

“Following changeover, purifier tripped repeatedly; operating parameters were recorded as follows; deposits observed were photographed; corrective action taken was…”

That difference matters.

Practical takeaway

Record observations, not conclusions. Let the expert establish causation.

 

THE COMMERCIAL CLOCK DOES NOT STOP FOR THE TECHNICAL INVESTIGATION

This is one of the most important lessons.

Owners may want to wait until the chemist has completed the investigation before notifying Charterers.

That can be risky.

A Charter Party may contain a specific bunker-claim notification period.

Therefore, two processes should run in parallel:

Technical investigation

What happened?

Contractual protection

What must Owners notify, and by when?

Do not allow the technical investigation to cause a contractual deadline to be missed.

A preliminary notification can protect the position while the technical investigation continues, subject of course to the actual Charter Party wording and legal advice.

Practical takeaway

Technical certainty may take time. Contractual deadlines may not.

 

WHY THE OPERATOR MUST CONNECT THE DOTS

A bunker problem crosses departmental boundaries.

Chief Engineer

Sees the machinery.

Master

Sees the vessel's overall operation.

Superintendent

Coordinates technical response.

Operator

Coordinates the wider commercial and operational picture.

Chartering Team

Looks at contractual rights and obligations.

P&I / Lawyers

Protect the claims position.

Chemist

Assesses the technical evidence.

The risk comes when each person sees only their own piece.

Leadership means putting the pieces together.

 

A SIMPLE BUNKER INCIDENT RESPONSE FRAMEWORK

When abnormal bunker behaviour appears, use seven steps:

01 — DETECT

Identify the abnormality early.

02 — RECORD

Create a clear contemporaneous record.

03 — PRESERVE

Protect samples, sludge, photographs and documents.

04 — NOTIFY

Check Charter Party notification requirements immediately.

05 — ANALYSE

Bring in competent technical expertise.

06 — TEST

Agree the correct sample, laboratory and parameters.

07 — DECIDE

Make the operational and commercial decision based on evidence.

This sequence helps prevent two common mistakes:

Jumping to conclusions.

and

Waiting too long to act.

 

FIVE QUESTIONS EVERY OPERATOR SHOULD ASK

When a bunker problem appears, stop and ask:

1. WHAT DO WE KNOW?

Separate facts from assumptions.

2. WHAT CHANGED?

Identify the timeline.

3. WHAT EVIDENCE DO WE HAVE?

Samples, photographs, records, reports.

4. WHAT DOES THE CHARTER PARTY REQUIRE?

Especially notification and sampling provisions.

5. WHAT MUST WE DO TODAY?

Not next week.

Today.

That final question is often the difference between good claims management and poor claims management.

 

SHIPOPSINSIGHTS ACTION CHECKLIST

⚓ MASTER

Record events clearly. Photograph abnormal conditions. Communicate early.

⚙️ CHIEF ENGINEER

Monitor purifier performance and engine parameters. Preserve physical evidence.

🔧 TECHNICAL TEAM

Build the before-and-after technical picture.

📋 OPERATOR

Run technical and contractual investigations in parallel.

📑 CHARTERING TEAM

Check the Charter Party before agreeing sampling or testing arrangements.

🛡️ CLAIMS / P&I

Protect notification rights and evidence while the technical investigation develops.

👨‍🎓 YOUNG OFFICERS

Learn one professional habit:

When something abnormal happens, don't just fix it. Record what happened, what you found and what changed.

That habit will serve you throughout your maritime career.

 

THE BIGGER LESSON

A bunker dispute is rarely just about fuel.

It is about judgement under uncertainty.

The first laboratory report may not provide the final answer.

The first machinery failure may not prove causation.

The first theory may turn out to be wrong.

The professional response is therefore neither:

“The fuel is definitely bad.”

nor:

“The fuel is within specification, so there is no problem.”

The professional response is:

“Something abnormal has happened. Let's establish the facts, preserve the evidence, obtain the right expertise, protect our contractual position and determine the cause scientifically.”

That is how experienced maritime professionals operate.

 

⚓ SHIPOPSINSIGHTS EXECUTIVE INSIGHT

DON'T JUST TEST THE FUEL. INVESTIGATE THE STORY.

The real story begins when the bunker is delivered.

It continues through:

Sampling

→ Storage

→ Changeover

→ Purification

→ Engine operation

→ Abnormal symptoms

→ Evidence

→ Expert analysis

→ Contractual action

A laboratory report is one chapter.

The vessel's operational record is the rest of the story.

And when a bunker problem becomes a claim, the strongest position is not created by the loudest argument.

It is created by the clearest chain of evidence.

That is the difference between suspecting a bunker problem and professionally managing one.

⚓ ShipOpsInsights

Think beyond the fuel. Understand the system. Protect the evidence. Manage the risk.