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Performance surveillance for dehydrators and desalters

Performance surveillance is a daily engineering review of the signals that a dehydrator or desalter control system already records: interface level, power unit secondary voltage and current, inlet temperature, mixing valve pressure drop, wash water and demulsifier rates, treated crude flow, and the laboratory BS&W and salt. Axsia Howmar engineers read them against the design model of the vessel, against each other and against their own trend, and return a green, amber or red note with the cause and the action. Most faults in an electrostatic treater show in the power unit signals weeks before they show in the crude; surveillance finds them while the repair is still a planned visit and a small part, not a shutdown and a long-lead spare. It needs no new instruments and works for units of any make.

All of them already on the DCS; no new instrument on the vessel: 8 signals
Read against the design model by the engineers who design the equipment: Every day
A note with the cause and the action, by exception: Green, amber, red

Ask about surveillance for your unit Already have a symptom? Troubleshooting

The signals

The control room already has everything the review needs

Interface level and its controller output, the secondary voltage and current of each power unit, inlet temperature, the pressure drop across the mixing valve, wash water and demulsifier rates, treated crude flow, and the laboratory BS&W and salt. Every dehydrator and desalter records most of them; a well-instrumented one records all eight. What is missing on most plants is anyone reading them together, every day, against what the vessel was designed to do.

Operations staff watch the alarms, and the alarms are set for the day the unit fails, not for the weeks before. The slow drifts that come first never cross an alarm limit, and the treated crude is the last thing to show them.

A typical desalter graphic on a distributed control system, with the signals surveillance reads called out. The screen image is deliberately softened so that no tag number, plant identifier or value is legible.

How it works

From the tags you already have to a decision you can plan

A daily export from the plant historian, or a read-only link, brings the eight signals to Axsia Howmar. The engineers who design electrostatic coalescers check them against the design model of the vessel for the water cut, temperature and rate of the day, against each other, and against their own trend. The result is a green, amber or red note: green is a weekly line; amber is a drift with its probable cause and the operating change or inspection that settles it; red is a hardware signal with the part to have ready and the planned visit to fit it.

Expected against actualThe vessel model says what voltage and current the grids should draw today. A gap is the first sign of water or gas where it should not be.
Balance between unitsPower units on one vessel should load alike. One drifting away from the others is a hardware signal: a connection, a bushing, an insulator.
Rate of change and noiseCreep that an alarm limit never sees, and the rising noise that comes before a trip, are caught by trend.
Cross-checksLevel against water out-flow, temperature against BS&W, chemical rate against both: the pairs that separate a process cause from an equipment cause.

The surveillance service from signal to decision: eight tags from the DCS or historian, four checks every day, an engineer review, and a green, amber or red note.

What it finds

The treater was on specification the whole time. The power unit was not.

A published case from a heavy-oil desalter in the Middle East, running on brine above 100,000 ppm with limited local maintenance support and long-lead spares, shows what the power unit signals can do. Streaming data from the units was reviewed remotely against expected behaviour, and within a week of monitoring starting a non-conformance in the secondary voltage of one unit stood out. The cause was an internal connector that had been over-tightened with a wrench instead of by hand, producing a voltage imbalance that was quietly damaging the unit.

The connector was replaced on a planned visit for the price of a small part, with no loss of production. Left alone, it would have ended with a damaged treater, a long-lead spare and a reduced facility output. Throughout, the treated crude was on specification: product quality alone would never have raised the alarm. The chart below is drawn from that case; it is illustrative, not plant data.

Surveillance is a review of the signals supplied. It reports what the data shows and what to do about it; it is not a guarantee of performance or of freedom from failure.

Illustrative trend drawn from a published case: the secondary voltage of one power unit diverges from its neighbour and its noise rises; the imbalance is flagged within days and the connector replaced on a planned visit, while the treated crude BS&W stays on specification throughout.

To start

What we need from you

Historian tags
The eight signals, with units and sampling interval, as a daily export or a read-only link.
Datasheets and nameplates
Vessel and power unit data to build the model the signals are checked against.
Laboratory results
BS&W and salt as sampled; the cross-check between the electrical signals and the product.
Maintenance history
Power units, bushings and insulators, so a new drift is not confused with a known condition.

How we approach Performance surveillance for dehydrators and desalters

Baseline
The design basis, the current operating window and three months of history establish what normal looks like for this vessel, this crude and this season.
Connect
A daily export from the historian, or a read-only link, for the eight signals. Nothing is written to the plant system and no instrument is added to the vessel.
Review every day
Expected against actual from the vessel model; balance between the power units on one vessel; rate of change and noise; cross-checks between level, water out-flow, temperature, chemical rate and BS&W.
Report by exception
Green: a weekly note. Amber: a drift with its probable cause and the operating change or inspection that settles it. Red: a hardware signal with the part to have ready and the planned visit to fit it.
Close the loop
What was found, what was done and what the signals did afterwards go into the unit's record, so the next review starts from a better baseline.

Deliverables from Performance surveillance for dehydrators and desalters

Daily status: Green, amber or red for each vessel, with one line of reason
Amber and red notes: The signal, the probable cause, the action, and the part or spare to have ready
Monthly performance summary: Trends against the design model, chemical and wash water usage, and the operating window recommended for next month
Unit record: A running history of findings, actions and outcomes for the vessel

Data we need from you for Performance surveillance for dehydrators and desalters

Data we need from you for Performance surveillance for dehydrators and desalters
Data item	Why it is needed
Historian tags for the eight signals, with units and sampling interval	The review runs on these
Original datasheets, power unit nameplates and the current operating window	Builds the vessel model the signals are checked against
Laboratory BS&W and salt results, as sampled	The cross-check between the electrical signals and the product
Maintenance history of the power units, bushings and insulators	Separates a new drift from a known condition
A named contact in operations	An amber or red note needs someone who can act on it

Partial data is normal. Send what you have and we will tell you what else matters.

Typical outcomes of Performance surveillance for dehydrators and desalters

Faults in power units, bushings and insulators found from their electrical signature, before product quality is affected (Review of the signals supplied; dependent on the instrumentation and the data delivered)
Repairs moved from unplanned shutdowns to planned visits, with the spare already on site (Where the finding is acted on within the time the note gives)
Chemical and wash water set from what the vessel needs rather than from habit (Subject to the operating constraints of the plant)
A documented operating history of the unit (For design reviews, revamps and hand-over)

Outcomes depend on the condition of the equipment, the feed and the operating envelope. Nothing on this page is a performance guarantee.

Questions engineers ask

Frequently asked questions

How is performance surveillance different from troubleshooting?

Troubleshooting starts from a symptom that has already appeared and works back to the cause. Surveillance starts every day from the signals and looks for the drift that comes before the symptom. The two share the same engineers and the same vessel model; surveillance is what keeps most units from ever needing the troubleshooting service.

What can the power unit signals tell you that the BS&W cannot?

The treated crude only goes off specification when the vessel has already lost part of its capacity. The secondary voltage and current of each power unit respond at once to a change in the vessel: a rising interface, water or gas in the grid zone, a tracking insulator, a loose connection, an unbalanced output. A published case from a heavy-oil desalter showed a voltage imbalance within a week of monitoring that was traced to an internal connector over-tightened with a wrench; it was replaced on a planned visit for the cost of a small part, with no loss of production, while the crude had been on specification throughout.

Do you need access to our control system?

No. A daily export of the eight tags, or a read-only link from the plant historian, is enough. Nothing is written back to the plant system, no software is installed on it, and no instrument is added to the vessel. The arrangement is agreed with your control and IT staff before anything is connected.

Does it work for units Axsia Howmar did not design?

Yes. The vessel model is built from the datasheets, nameplates and drawings of the unit, whoever built it, and the signal list is adapted to the instrumentation that exists. Dehydrators, desalters, degasser dehydrators and prewash coalescers of any make are covered.

Is this a guarantee that the unit will not fail?

No. Surveillance is a review of the signals supplied: it reports what the data shows and what to do about it. Faults that leave no electrical or process signature, or that develop faster than the review interval, can still occur. What it changes is how many faults are caught early, and how many repairs become planned work.

Talk to an engineer about your unit

Tell us the equipment, the duty and what you are seeing. Partial data is normal: send what you have and we will tell you what else matters. We acknowledge every enquiry within 1 working day.

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Performance surveillance for dehydrators and desalters

The control room already has everything the review needs

From the tags you already have to a decision you can plan

The treater was on specification the whole time. The power unit was not.

What we need from you

Historian tags

Datasheets and nameplates

Laboratory results

Maintenance history

How we approach Performance surveillance for dehydrators and desalters

Baseline

Connect

Review every day

Report by exception

Close the loop

Deliverables from Performance surveillance for dehydrators and desalters

Data we need from you for Performance surveillance for dehydrators and desalters

Typical outcomes of Performance surveillance for dehydrators and desalters

Solutions related to Performance surveillance for dehydrators and desalters

Engineering services for Performance surveillance for dehydrators and desalters

Spare parts related to Performance surveillance for dehydrators and desalters

Insights and papers on Performance surveillance for dehydrators and desalters

Glossary terms used with Performance surveillance for dehydrators and desalters