Findings
The boiler’s feedwater tank was found to have excessive sediment buildup, causing slight fluctuation in boiler pressure and reduced heating efficiency.
The sediment layer indicated inconsistent water treatment and infrequent blowdown, leading to partial blockage at the feedwater inlet strainer.
Root Cause
The excessive sediment buildup in the boiler feedwater system was primarily caused by inconsistent water treatment and infrequent blowdown, resulting from inadequate operator adherence to the established maintenance schedule.
Contributing factors include insufficient monitoring of feedwater quality, leading to undetected increases in total dissolved solids (TDS) and sludge accumulation, and a clogged feedwater strainer that was not cleaned according to the preventive maintenance plan.
Solution
1) Perform immediate blowdown to remove accumulated sludge.
2) Clean or replace the feedwater strainer.
3) Reinstate proper water treatment dosing and implement a scheduled blowdown routine (daily/weekly depending on load).
4) Include feedwater quality checks in the preventive maintenance checklist.
DOSH Regulations for Boilers in Malaysia
Factories and Machinery (Steam Boiler & Unfired Pressure Vessel) Regulations 1970
This is the primary DOSH regulation under the Factories and Machinery Act 1967 that governs steam boilers and unfired pressure vessels requiring regular inspection, maintenance, and safety controls of boilers.
- OSHA on Certification and Competency Requirements - requirement for competent persons - both a steam boiler engineer and boiler operator must be designated.
- Certificate of Fitness (CF) - Boiler/pressure vessels require a valid DOSH's CF issued after inspection to confirm compliance with the safety regulations.
(This case study was from early 2023 but latest DOSH Regulations (2024–2025 Updates) - New CF Regime - OSH Regulations 2024 (PUA 99/2024) effective 1 June 2024 - (Plant requiring CF) Certain plants, including steam boilers, must obtain a CF before they can operate. Periodic inspections required to maintain validity. CF is not unlimited: the validity is capped (e.g. as per industry commentary, not exceeding 15 months).
If there are repairs that affect the strength of the boiler, DOSH may require another hydrostatic test before recertification.
- Owner/Occupier Duties - must operate and maintain the boiler in a safe and proper condition including testing the control and safety devices (e.g., safety valves, pressure gauges) periodically according to manufacturer’s recommendations, keeping logbook and records of operation, inspections, repairs, breakdowns.
During a DOSH inspection, they need to ensure the boiler is ready for inspection per DOSH’s checklist
SSI
Plants approved under SSI, the CF period can be extended much longer depending on type of plant, risk category, integrity history
inspection intervals approved by DOSH,
Typical extensions under SSI may allow:
a) Pressure vessels to run on extended intervals
b) Inspection schedules aligned with API 510, API 570, API 653
c) Boilers or critical equipment to follow risk-based inspection (RBI) intervals
d) Major shutdown cycles (e.g., every 4–6 years) instead of annual shutdowns
The plant requires :
1) RBI (risk based inspection)
2) Documented degradation mechanisms
3) Predictive maintenance
4) Certified in-house inspection engineers
5) DOSH audit/verification
SSI does not remove the need for CF.
It only allows extended intervals for inspection and CF renewal with DOSH approval.
e.g.
A normal air receiver or pressure vessel:
a) CF renewed every 12–15 months
Same vessel under SSI with RBI approval:
- CF may be aligned to a 3–5 year inspection cycle
- Internal inspection may coincide with major turnaround
- Online NDT and monitoring replace some physical shutdowns
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