Boiler Water Treatment
Water treatment protects the boiler and steam circuit against corrosion, deposits and contaminant carryover. A reliable sample, interpreted within the plant programme, connects the result with the possible cause, correction and follow-up.
Operational Explanation
Treatment aims to control corrosion, deposits and contaminant carryover into steam. An anomaly can also arise from feedwater, condensate return, deaeration or level control: chemical correction must accompany investigation of the cause. Wilhelmsen: boiler water risks.
The circuit includes make-up water, feedwater, the boiler and condensate return. Follow quality along this path: a boiler-water result does not automatically describe the condition of condensate or feedwater.
| Problem to prevent | Why it matters |
|---|---|
| Corrosion | It can damage metal and pipework; dissolved oxygen and unfavourable chemical conditions are factors to control. |
| Deposits | They impair heat transfer and may contribute to local overheating. |
| Carryover into steam | Water and contaminants can reach steam users; water quality and operating conditions need to be considered together. |
Treatment combines incoming-water quality, feedwater conditioning, the products specified by the programme and monitoring of results. Heating and deaeration, where fitted, help limit dissolved gases. Spirax Sarco: feedwater and conditioning.
Chemical functions differ: pH/alkalinity control, residual oxygen removal, hardness and deposit control. The programme may specify scavengers, phosphates or conditioners/polymers for the plant. Identify products and their associated checks in the programme, without independent substitutions.
Regulatory Reference
ISM Code 10.1–10.2 and 10.4: maintenance procedures, inspections at appropriate intervals, reporting non-conformities with a possible cause if known, corrective action and records integrated into the routine.
These paragraphs establish the management framework; parameters, limits and chemistry depend on the boiler and applicable programme. Maker's manual, supplier instructions, test methods and PMS/SMS arrangements need to be consistent. ISM Code, EMSA 2018 text consulted, §10.
Wilhelmsen and Spirax Sarco material explains risks and methods as manufacturers' technical sources. Product recommendations or industrial-plant examples need to be read within their scope; they are not IMO prescriptions for doses, six daily tests or one common threshold.
Scope of Application
Familiarisation with water control in marine steam systems. Boiler type and pressure, materials, make-up water, condensate recovery, installed treatment and instruments determine the programme.
This page connects the sample, result and follow-up. Boiler starting, combustion and protection are addressed in Boiler Operations; doses, valve sequences and work on hot pressurised water are performed by assigned personnel under plant instructions.
Procedure / How to Complete It
Take samples through the specified sample cooler, following the manual and hot-water/pressure precautions. Record the sample point, reference temperature and method; verify calibration and reagents. Conductivity and TDS are related but are not the same quantity: use the method’s conversion without interchanging µS/cm and mg/l. Spirax Sarco: MS1 instructions.
- Identify the programme. Link each check to its specified sample point, method, units, limit and frequency (for example pH/alkalinity, hardness, conductivity or product residual, where required); distinguish feedwater, boiler water and condensate.
- Prepare a reliable measurement. Use instruments, reagents and sampling arrangements under the prescribed conditions; note anomalies that may make the result unrepresentative.
- Read the result. Compare it with the programme limit and previous results obtained under comparable conditions; consider load, make-up water and circuit changes.
- Manage a deviation. Report the out-of-limit result, confirm the measurement by the method and investigate possible causes in feedwater, condensate, conditioning or dosing.
- Follow the specified action. Chemistry and blowdown serve different purposes; apply the authorised correction and verify its effect without copying quantities or timings from another plant.
- Leave a clear follow-up. Record the result, action, subsequent check and defects still open; connect relevant work with PMS and handover.
Blowdown for dissolved-solids control and bottom blowdown for sludge have different purposes. Method and arrangements depend on the boiler; increasing blowdown without diagnosis also loses water and energy. Spirax Sarco: purpose of bottom blowdown.
Practical Example
Learning scenario. Boiler-water conductivity rises after a change in make-up water. Before attributing the result to contamination, the team checks that sample point, units and method conditions are comparable with the previous result. A repeat measurement confirms deviation from the ship's limit.
Assigned personnel examine the water path and available feedwater and condensate results, distinguishing observations from hypotheses. Action follows the programme; the record connects the make-up change, results, correction and subsequent verification. If the cause remains open, it is handed over with an owner and follow-up. The scenario does not prescribe blowdown minutes or product quantities.
What Typically Goes Wrong
A reading may look plausible while coming from the wrong point or different conditions. A return within limits after correction may also conceal continuing contamination: both the result and the cause need follow-up.
Conductivity measures an electrical property of water; TDS expresses dissolved solids. Temperature, composition and sample preparation affect the relationship. Use the method and conversion specified for that check; do not directly compare µS/cm with mg/l, or an unneutralised measurement with a result obtained by another method. Spirax Sarco: measuring and controlling TDS.
Common Mistakes Mistake Library
| Mistake | Consequence | How to avoid it |
|---|---|---|
| Comparing samples from different points or methods as equivalents. | A measurement difference may be mistaken for a plant change. | Trace the point, method, units and sample conditions. |
| Treating conductivity and TDS as the same quantity. | The result is interpreted against the wrong units or limit. | Apply the conversion belonging to the relevant method. |
| Correcting chemistry without investigating a persistent deviation. | A feedwater or condensate defect may continue. | Connect measurement, possible cause, action and subsequent verification. |
| Copying tests, doses or blowdown timings from another boiler. | Treatment may be unsuitable for the circuit and programme. | Use plant parameters and instructions; clarify deviations with responsible personnel. |
What the PSCO Checks
The 2025 PSC procedures address machinery condition and maintenance, including leaks, corrosion and defective indicators and safety devices. A completed record alone does not show that a defect has been resolved; the check needs to be placed in the context of the inspection. IMO A.1206(34), appendix 6, §3.
Operational Tips
- Keep a sample-point map using the same identifiers as the record.
- Note make-up, load or condensate-return changes relevant to interpreting results.
- Hand over deviations and outstanding checks with an owner and follow-up.
- Use product instructions and handling precautions; reagent availability and condition are part of a reliable test.
Chemical monitoring needs to accompany management of the circuit and training of assigned personnel. Wilhelmsen: programme, monitoring and training.
Preparation checklist
- Programme relevant to the boiler and instructions available.
- Sample points, parameters, units, limits and frequencies identified.
- Sampling arrangements, instruments and reagents usable according to instructions.
- Results comparable with circuit conditions and the trend.
- Out-of-limit results reported with a possible cause if known.
- Correction and subsequent verification traceable.
- Open defects, responsibilities and follow-up linked with handover/PMS.
FAQ
Related Topics
Certified substantive revision: 12 October 2026 · page fingerprint 23534f2ac398