Boiler & Economiser Servicing in Netherlands.

Marine boiler and economiser servicing

Marine boiler and economiser servicing covers the inspection, cleaning, repair and testing of auxiliary oil-fired boilers, composite boilers and exhaust gas economisers (also called exhaust gas boilers). On most merchant ships these units provide steam for fuel heating, cargo heating and domestic services, and on tankers they may drive cargo pump turbines. Boilers combine pressure parts, combustion equipment, controls and safety devices, so a defect can mean loss of steam, cargo claims, a class condition or, in the worst cases, an explosion or soot fire.

vslSafety arranges boiler engineers, burner technicians and maker-authorised service engineers to attend during a port call, at anchorage, or as part of a dry-dock or repair period, with class survey support where required.

Regulatory requirements and standards

Boiler surveys are primarily a class matter. IACS Unified Requirement Z18 (Survey of Machinery) sets the common baseline adopted by IACS member societies:

• Water-tube boilers for main propulsion, all other boilers of essential service, and non-essential boilers with working pressure above 3.5 bar and heating surface above 4.5 m² are to be surveyed internally.
• There must be a minimum of two internal examinations in each five-year special survey period, and the interval between any two examinations must not exceed 36 months. An extension of up to three months may be granted in exceptional circumstances after external examination, safety valve easing gear and protective device tests, and review of records.
• At each survey, boilers, superheaters and economisers are examined internally on the water-steam side and fire side, mountings and safety valves are examined, and safety valve adjustment is verified.
• An external survey, including tests of safety and protective devices and of the safety valve using its relieving gear, is carried out annually within the annual survey window.
• For exhaust gas heated economisers, where steam cannot be raised in port, the safety valves may be set by the chief engineer at sea and recorded in the log book for class review. On shell-type exhaust gas economisers, accessible welded joints are visually examined for cracking, and non-destructive testing may be required.
• Records of operation, maintenance, repair history and feedwater chemistry since the last survey are reviewed.

SOLAS chapter II-1 contains general requirements for boilers and machinery, and the ISM Code requires the company to maintain equipment and test critical systems. Repairs to pressure parts must follow class-approved procedures with qualified welders and material certificates.

Survey and servicing intervals

What the service includes

• Opening up, cleaning and preparation for class internal survey, including gas-side and water-side inspection
• Burner overhaul, nozzle and atomiser renewal, ignition electrode and flame scanner checks, and combustion tuning with flue gas analysis
• Test of low-water level trips, flame-failure shutdown, high-pressure cut-outs, alarms and automatic controls
• Safety valve overhaul, lapping and setting, with class witness where required
• Exhaust gas economiser water washing, soot deposit removal and tube inspection
• Leak investigation, tube plugging or renewal, and hydrostatic testing after repair
• Refractory repair, casing, uptake and furnace inspection
• Review of water treatment records and chemical dosing, with recommendations

Boiler types and makers covered

Engineers commonly work on vertical and horizontal oil-fired auxiliary boilers, composite boilers combining oil firing and exhaust gas heating, smoke-tube and water-tube exhaust gas economisers, and thermal oil heaters. Makers encountered include Alfa Laval (Aalborg), Saacke, Kangrim, Miura, Mitsubishi and various yard-supplied units. Many burner and control systems need maker-specific spare parts and software access.

Common defects and PSC deficiencies

• Soot fires in exhaust gas economisers, typically after prolonged low-load operation with poor cleaning and soot-blowing routines
• Tube leaks and corrosion from poor feedwater treatment, oxygen pitting or low-temperature acid corrosion on the gas side
• Safety valves seized, incorrectly set or with easing gear inoperative
• Low-water level and flame-failure trips bypassed or not tested
• Refractory damage causing hot spots on the casing
• Oil leaks around burners and insulation soaked with fuel, a fire risk that PSC officers readily notice

Opening an economiser that has not cooled can admit fresh air and trigger a fire, so follow the maker’s cooling and opening procedure.

Certificates and documents you receive

• Service report with findings, measurements and photographs
• Safety valve setting record, witnessed by class where required
• Combustion analysis and trip test record
• Hydrostatic test record and NDT reports after repair
• Material and welder certificates for pressure part repairs

The class survey report and any condition of class are issued by the attending class surveyor.

How to prepare the vessel

For internal work the boiler must be shut down, cooled, depressurised, drained and ventilated, which often takes more than a day. Treat the boiler and economiser as enclosed spaces with atmosphere testing and a permit. Arrange alternative steam if fuel heating is needed. Book class early if the internal survey is due. Where thickness measurement or crack detection is expected, combine the attendance with non-destructive testing and ultrasonic thickness measurement. Larger machinery repairs can be coordinated with engine and machinery overhaul teams.

Information needed for a quotation

• Vessel name, IMO number, flag and class
• Port, ETA/ETD and whether the vessel is alongside, at anchor or in dry dock
• Boiler and economiser maker, model, type, working pressure and fuel
• Scope: survey preparation, burner service, leak repair, cleaning or safety valve work
• Last survey date, class status and any condition of class
• Symptoms, alarm history, water treatment records and spare parts on board

vslSafety coordinates a suitable boiler service provider at the vessel’s port and confirms tools, spares and class attendance before mobilisation.

Frequently asked questions

How often must a ship’s boiler be surveyed internally?

Under IACS UR Z18, applicable boilers require at least two internal examinations in each five-year special survey period, with no more than 36 months between examinations. An extension of up to three months can be granted in exceptional circumstances, such as unavailable repair facilities, after an external examination and tests. An external survey with safety device tests is also carried out annually.

What causes exhaust gas economiser soot fires?

Soot fires usually follow a build-up of oily soot on the gas-side tubes, often from prolonged low-load operation, poor combustion and inadequate cleaning. A hot spot can ignite the deposit. Prevention relies on regular soot blowing, periodic water washing, monitoring gas-side pressure drop and keeping the main engine in good combustion condition.

Can boiler tube leaks be repaired in port?

Minor leaks can often be dealt with by plugging tubes within limits accepted by class and the maker, provided the boiler can be cooled and opened. Tube renewal and welding on pressure parts require approved procedures, qualified welders, NDT and class attendance, and are better planned for a longer port stay or dry dock.

Why does water treatment matter?

Poor feedwater chemistry causes scale, corrosion, pitting and carry-over, which lead to overheating and tube failure. Class reviews feedwater chemistry records at boiler surveys, and consistent testing and dosing is one of the cheapest ways to extend boiler life.