Boiler (motor) — Most Asked Questions
45 questions asked about boiler (motor) across the General and Fn 6 and Fn 3 and Fn 4b papers, heaviest first. 3 of them are must-master.
Learn the system first
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1 Boiler water test?
Also asked: “Boiler water test(ppm”
Answer
Boiler water is tested to catch seawater contamination, wrong alkalinity, dissolved oxygen and hardness before they scale, pit or corrode the boiler.
- pH test: 7.5–14.0 for boiler water, 6.5–10.0 for condensate — warns of acidity/alkalinity drift and sets boiler-compound dosage. Aim boiler pH 10–11.
- Chloride test: warns of seawater contamination of the feed system and sets blowdown; act if chlorides exceed about 300 ppm.
- Hydrazine (Amerzine) test: dissolved-oxygen scavenger reserve — prevents oxygen pitting in boiler, steam and condensate lines.
- Phosphate test: keep 40–60 ppm reserve so any hardness salts entering are neutralised instead of scaling tubes.
Surveyor follow-up: chlorides are climbing — what two actions do you take?
Full theory: Boiler Water Treatment, Testing, and Blowdown -
2 Shell expansion plan?
Answer
A shell-expansion plan flattens the ship’s 3-D shell plating into one 2-D drawing, measured around the girth so side and bottom appear as a continuous whole.
- It is the arrangement of the shell plating taken from a 3-D model and drawn in 2-D, with vertical dimensions taken around the girth rather than as direct vertical projection.
- Side and bottom plating show as one continuous sheet, with plate numbering and strake lettering for reference — strakes lettered outward from the keel, starting at the garboard strake.
- It also carries openings in shell, deck edges, stringers, girders, bulkheads, stem and stern details, bossings and frame lines.
- Use it for: finding any plate by number, planning steel renewals, and answering where shell thickness increases (deck, bottom, and midship shear regions).
Surveyor follow-up: point at the drawing and name the first strake out from the keel — then the one at the turn of bilge.
Full theory: Midship Sections Compared by Type of Ship -
3 How to blow down the boiler?
Also asked: “Tell me about boiler blowdown procedure”
Answer
Blow down to dump sludge, scum and dissolved solids: scum off the top, solids off the bottom, ship-side valve first and water level never lost.
- Purposes: remove solids, dirt, foam and oil from boiler water and hold density down.
- Two routes: scum blowdown skims the surface layer; bottom blowdown dumps settled impurities.
- Three depths: flash blowdown for settled sludge, partial blowdown to the gauge-glass bottom level when chlorides, phosphates or alkalinity run high, complete blowdown only for survey or maintenance.
- Sequence for full/partial: kill fires, shut steam stops, let pressure fall to about 5 bar, open scum cock first, then the shipside valve — open overboard side first and close it last so the boiler valve never takes the full differential alone.
Surveyor follow-up: chlorides just failed high — flash, partial or complete blowdown, and how do you confirm the result?
Full theory: Boiler Water Treatment, Testing, and Blowdown -
4 HOW TO BLOW THROUGH BOILER GAUGE GLASS?
Answer
Blow the glass to prove both passages: steam jet first, water jet second, then refill and watch the level settle true.
- Shut steam and water cocks, open the drain, then crack the steam cock — a strong steam jet proves the steam leg clear.
- Shut steam, open the water cock — a strong water jet proves the water leg clear.
- Shut water and drain, reopen water so the glass fills above normal, then open steam and let the level settle to the true boiler level.
- No water after blowing means no water in the boiler: shut down at once and ease pressure — never refill a hot empty boiler.
Surveyor follow-up: level sits high and lazy after blow-through with steam cock shut — which leg is choked?
Full theory: Normal Operation, Load Control, and Watchkeeping -
5 boiler safety valve setting?
Answer
Safety valves lift before the boiler is hurt: set pressure plus a capped accumulation, proved by steam and logged.
- Three numbers matter: working pressure, lifting pressure above it, and accumulation capped at 10% over the set pressure.
- Example quoted: 7 bar working, valve set at 9 bar, accumulation not above 9.9 bar.
- Economiser and receiver valves set a touch higher than their connected boiler valves so the right valve lifts first.
- Set under steam, lock tamper-proof, gag off companion valves during the test, log exact lifting pressures with the chief and send a copy to class at the next port.
Surveyor follow-up: valve lifts at set pressure but will not reseat — spring or seat, and do you gag it to finish the watch?
Full theory: Boiler Safety Devices and Emergency Response -
6 Type of boiler
Also asked: “Type of boiler and description”
Answer
Marine boilers split by who is inside the tubes: fire-tube Scotch for auxiliaries, water-tube for big steam plant, exhaust-gas and composite for waste heat.
- Fire-tube: hot gas inside tubes surrounded by water — the Scotch auxiliary boiler, simple and forgiving.
- Water-tube: water inside small generating tubes in the gas path — fast steam-raising for propulsion and large loads.
- Exhaust-gas boiler recovers main-engine heat underway; composite fires oil in port and exhaust gas at sea, sometimes with an economiser.
- Say your ship’s type first, then working pressure and use — surveyors fail generic answers.
Surveyor follow-up: why does the exhaust-gas boiler need its own circulation and safety valves?
Full theory: Boiler Plant Working Flow -
7 Boiler gauge glass blow down?
Answer
Blow the glass to prove both legs: steam jet first, water jet second, then refill and watch the level settle true.
- Shut steam and water cocks, open the drain, then crack steam — a strong jet proves the steam leg clear.
- Shut steam, open water — a strong jet proves the water leg clear.
- Shut water and drain, reopen water so the glass fills high, then open steam and let the level settle.
- No water after blowing means no water in the boiler: shut down at once, ease pressure, never feed a hot empty boiler.
Surveyor follow-up: level sits high and lazy after blow-through — which leg is choked?
Full theory: Normal Operation, Load Control, and Watchkeeping -
8 Flame failure in boiler reason?
Also asked: “Faulty flame in boiler. Reasons?”
Answer
Flame failure is fuel, air or eyes: low oil pressure, dirty burner, or a blind photocell shutting the plant down.
- Low fuel-oil pressure or lost suction starves the burner — the commonest trip.
- Unmaintained burner with choked atomiser, wrong viscosity or bad air setting will not hold a flame.
- The photocell watches the flame and shuts fuel on failure; a dirty cell glass trips a healthy burner.
- After any trip ventilate, find the cause and relight deliberately — never reset into an unpurged furnace.
Surveyor follow-up: trips repeatedly with pressure normal — fuel, air or photocell, and what do you check first?
Full theory: Boiler Safety Devices and Emergency Response -
9 safety valve. Relief valve
Also asked: “safety valve anf relief valve diff”
Answer
Safety valves pop on steam drums where explosion threatens; relief valves ease pressure on liquid lines — fast pop versus steady lift.
- Safety valves open by inlet static pressure with rapid pop action, vented to a safe place.
- Relief valves open progressively against a spring to hold liquid-system pressure within range.
- Boiler example: 7 bar working, valve set at 9 bar, accumulation capped at 10% to 9.9 bar.
- Test under steam to exact lifting pressure, lock tamper-proof and log with the chief for class.
Surveyor follow-up: valve lifts at set pressure but will not reseat — spring or seat, and do you gag it?
Full theory: Boiler Safety Devices and Emergency Response -
10 Boiler water low level test
Also asked: “boiler water testing”
Answer
Prove the low-water alarm and burner cutout for real by dropping the float chamber — test buttons never count.
- Test on every watch or daily by draining the chamber so the floats actually fall with the level.
- Low water must alarm first; at low-low the burner trips and locks out until reset.
- Alarm points stack low, low-low, high and high-high with feed-water and fuel-pressure trips alongside.
- After the test blow through the glass, refill, reset and log level, time and burner response.
Surveyor follow-up: alarm sounds on test but the burner keeps firing — what has failed?
Full theory: Normal Operation, Load Control, and Watchkeeping -
11 Safety valve overhaul
Also asked: “compressor valve overhaul”, “butterfly valve overhaul”
Answer
Overhaul safety valves by lapping the seat, proving the spring, setting under steam and locking tamper-proof.
- Strip, clean and lap seat to disc until the contact ring is unbroken all round.
- Check springs, spindles and easing gear for cracks, stretch and free movement.
- Set lifting pressure under steam with companion valves gagged, then remove gags and reconnect easing gear.
- Record exact lifting pressures in the log with the chief and send a copy to class at the next port.
Surveyor follow-up: valve lifts at set pressure but weeps on reseat — lap again or renew the spring?
Full theory: Overhauling, Inspection, and Repair -
12 boiler safety?
Answer
Boiler safeties guard water, steam, fuel and flame: level alarms with burner cutout, safety valves, fuel trips and flame eyes.
- Water side: gauge glasses, low and high level alarms, low-low cutout, pressure gauge and air vent against vacuum.
- Steam side: safety valves, high-pressure alarm and easing gear kept rigged and free.
- Fuel and firing side: low oil pressure and temperature alarms, flame-failure and smoke-density trips, forced-draught-fan stop alarm.
- Prove by level-drop tests, steam lifts and photocell blackout — logged, never assumed.
Surveyor follow-up: name the one safety that stops the firing when the water vanishes — alarm or trip, and at what level?
Full theory: Boiler Safety Devices and Emergency Response -
13 How many blowdown valves per boiler
Also asked: “How many drain valve is there in boiler”
Answer
Blowdown valves run doubled in series: boiler-side valve full open first, throttling valve second — ordered so seats survive.
- Two valves in series on bottom blowdown with the boiler-side valve opened fully before the second is cracked.
- Working the sequence the other way cuts seats and leaves both valves weeping.
- Scum valves ride the drum separately with a shallow pan under normal level for oil and foam.
- All blowdown discharges through the blowdown line to the ship-side valve, never straight to bilge.
Surveyor follow-up: both blowdown valves weeping after throttling on the first — wrong order or worn seats, and what now?
Full theory: Boiler Water Treatment, Testing, and Blowdown -
14 Boiler uptake fire
Answer
Uptake fires burn soot in the gas path: starve air, cool boundaries, deluge only with flooding water — steam makes hydrogen.
- Stop blowers, shut exhaust valves tight on spring air, fight from the boundaries first.
- Soot fire identified by rising uptake temperature with water still circulating; metal fire by lost circulation.
- Lost circulation stops the feed pump and cools from outside — never trickle water into a dry hot uptake.
- Flood only where deluge gear exists with copious water to the seat; sips of water feed hydrogen fire instead.
Surveyor follow-up: soot fire or metal fire — circulation lost or holding, and what do you stop first?
Full theory: Troubleshooting the Boiler -
15 Q2.) Salt formations in boilers are detrimental to boiler efficiency. How and what are the salt formations and their effects in boiler functionality?
Also asked: “Q2. Scale formation in boilers is detrimental to boiler efficiency. How and what are the salts that cause scale formation and their effects on boiler fuctionality”
Answer
Dissolved salts bake into scale and sludge: calcium and magnesium coat tubes while phosphates drop them out for blowdown.
- Calcium and magnesium salts form hard scale on heating surfaces, choking heat transfer and overheating metal.
- Phosphate treatment converts them to soft sludge with coagulant gathering the grains off the surfaces.
- Sludge settles to the bottom for blowdown; scum skims the top — both proved by water tests on schedule.
- Low-pressure plant doses soda ash for alkalinity, higher pressures add phosphates with sludge conditioners and oxygen scavengers.
Surveyor follow-up: tubes scaling with phosphates correct — blowdown, dosage or feed, and what test proves it?
Full theory: Boiler Water Treatment, Testing, and Blowdown -
16 boiler manual firing
Also asked: “Boiler manually firing procedure”
Answer
Fire manually by vent, fill, circulate, purge, light and build: cold boiler lit in short burns with level watched throughout.
- Vent open with no pressure, steam stop shut, fuel circulating to maker temperature, water just above low level.
- Purge the furnace with the fan, light the burner after closing recirculation, then burn five minutes and rest fifteen.
- Repeat the short burns until steam shows at the vent, then shut it and raise pressure in steps.
- Easing gear proves safety valves on the way up; feed holds level against swelling as firing builds.
Surveyor follow-up: level swelling hard on first firing — feed, firing or venting, and what do you shut first?
Full theory: Normal Operation, Load Control, and Watchkeeping -
17 how to increase boiler efficiency
Also asked: “)Boiler efficiency how to improve”
Answer
Efficiency climbs on clean transfer, right air and recovered heat: treat water, trim excess air, blow soot, bank exhaust.
- Soft treated water with controlled blowdown keeps tubes free of scale that steals heat.
- Excess air trimmed to the burner with economisers banking funnel heat into feed.
- Soot-blowing on schedule with uptake temperatures watched keeps gas paths open.
- Prove by fuel per steam tonne trending down with oxygen, uptake and feed temperatures logged.
Surveyor follow-up: fuel up with oxygen normal and tubes clean — air, load or blowdown, and what gauge proves it?
Full theory: Troubleshooting the Boiler -
18 Boiler not firing reason
Answer
A silent boiler is starved, dirty or scared: fuel pressure, burner condition and flame guards decide in that order.
- Low fuel-oil pressure or lost pump suction starves the burner — prove pressure at the atomiser first.
- Unmaintained burners with choked tips and wrong air registers smoke, lift and trip on flame failure.
- Tripped flame guards, low water and high back-pressure lock out firing until reset and proved.
- Recover by fuel path, burner overhaul and air proving in sequence — relighting blind refires the fault.
Surveyor follow-up: flame-failure alarm with fuel pressure proved normal — burner, air or photocell first, and what proves it?
Full theory: Troubleshooting the Boiler -
19 Describe FIVE principle boiler water tests stating the reason for
Answer
Five tests keep the boiler alive: chloride orders blowdown, pH guards condensate, hydrazine kills oxygen, phosphate kills hardness, conductivity betrays all.
- Chloride reads salt load — rising ppm orders blowdown before foaming and carryover.
- Condensate pH held in band minimises steam-side and return-line corrosion.
- Hydrazine reserve proves dissolved oxygen scavenged against pitting and aeration.
- Phosphate reserve proves hardness locked into sludge instead of scale on tubes.
- Conductivity sums every contamination at once — climbing numbers fail the water before any single test does.
Surveyor follow-up: conductivity high with all five reserves in band — contamination, sampling or meter first?
Full theory: Boiler Water Treatment, Testing, and Blowdown -
20 Acculmation of pressure test in boiler
Also asked: “Hydraulic pressure testing of boiler”
Answer
Accumulation pressure is the extra lift the spring itself adds; the test proves the valve is right for the boiler at full fire.
- It is the rise in boiler pressure as the valve lifts and further compresses its own spring under maximum firing.
- Carried out on a new boiler or a new valve: shut feed water, close the main steam stop, raise the firing rate to maximum.
- Continue only as long as the water permits — then shut the fire and let the boiler cool without letting cold water in.
- Purpose is to prove the valve suits the boiler and to limit the pressure rise under full fire, with results recorded for class.
Surveyor follow-up: accumulation test run with feed water still on — does the reading prove anything, or must it be repeated?
Full theory: Normal Operation, Load Control, and Watchkeeping -
21 Action during boiler uptake fire
Answer
Uptake fires are soot fires: cut burners and fans, keep water full and blown, ease pressure and cool the casing from outside.
- Slow the engine, shut oil burners, draught fans, dampers and air register to starve the fire of air and fuel.
- Raise the water level full and blow down continuously so tube temperature stays below the flame.
- Reduce boiler pressure with the easing gear and spray water on the uptake casing to cool the affected area.
- For a self-sustaining fire, shut the engine and boiler, let it die down, then pressure-jet the smoke side and inspect damage.
Surveyor follow-up: soot fire on a two-engine ship with one boiler still raising steam — shut both, or fight with the spare?
Full theory: Boiler Safety Devices and Emergency Response -
22 Boiler Blow down procedure ( which valve to open first
Answer
Open the ship’s-side cock first, then crack the boiler valve gradually — the reverse can burst a corroded blow-down line.
- Allow as much time as possible after shutdown so the boiler cools before blowdown starts.
- Open the ship’s-side cock first, then ease the boiler blow-down valve gradually, keeping control of the discharge.
- Completion is felt by the noise falling and pressure dropping — start closing the boiler valve before cold sea enters.
- Close the boiler valve tight, then the ship’s-side cock, keeping the boiler from breathing in cold water.
Surveyor follow-up: boiler valve opened first on a corroded blow-down line — shut it, let it cool, or blow at once?
Full theory: Normal Operation, Load Control, and Watchkeeping -
23 Boiler blowdown procedure?
Answer
Blow down with the ship’s-side cock first, then the boiler valve gradually, and never let cold sea into a hot empty shell.
- Allow as long as possible after shutdown so the boiler cools before any water is moved.
- Open the overboard cock first, then ease the boiler blow-down valve — the reverse can burst a corroded external line.
- Keep water level up and circulation good during the blowdown, watching pressure and noise for the finish.
- Close the boiler valve tight, then the ship’s-side cock, so the boiler cannot breathe in cold water.
Surveyor follow-up: blowdown with the overboard cock shut and the boiler valve wide — stop, open the cock or bank the fire?
Full theory: Normal Operation, Load Control, and Watchkeeping -
24 Boiler guage glass showing correct level of water or not how will u check and if low water what will happen and what actions will u take
Answer
Glass levels are proved by blow-through: water must swing with the column, and if it vanishes from the sight glass the boiler is out of service.
- Blow through with both cocks open and watch the level swing — a stuck or false level reads steady while water moves.
- If water disappears from the bottom of the sight glass, act at once: the boiler is out of service, not watched.
- Water-tube boilers hold a small reserve and can lose it in seconds from a failed feed regulator, pump or burst tube.
- Restore level by feeding, not by blowing — then inspect the tubes, regulator and pump before the fire is raised again.
Surveyor follow-up: level steady in the glass but the low-water alarm sounding — glass, alarm or water first?
Full theory: Boiler Safety Devices and Emergency Response -
25 Boiler tube how to confirm leakage and plugging. For water tube boilers
Also asked: “How to find leaky boiler tube”
Answer
Find the tube by sound and smoke, then plug it properly — a water-tube leak is steam-blown, noisy and expensive to ignore.
- Stop firing, open the tube-side doors and listen for the hiss; water-tube leaks are far harder to find than smoke-tube ones.
- Blow through the tubes and watch for flame and noise at the fire side, and check for water leaking into the flue.
- Plug with a tapered drift or screwed plug sized to the tube after proving the leak and the tube’s condition.
- Record tubes plugged against the allowable number; too many plugs cost steam and the boiler’s rating on the certificate.
Surveyor follow-up: fourth tube plugged this voyage with the certificate limit at three — isolate, cut out or report first?
Full theory: Troubleshooting the Boiler -
26 Boiler tubes leaking-identification and rectification
Also asked: “Boiler tube leak rectification”
Answer
Leaking tubes hiss, whistle and steam into the flue; find them stopped, then plug or cut out and watch the plugged-tube count.
- Stop firing and open the tube-side doors, listening for the hiss — water-tube leaks are far harder to locate than smoke-tube ones.
- Blow through the tubes and watch for flame and noise at the fire side, and for water running into the flue.
- Plug with a tapered drift or screwed plug, or cut out where the leak is a fracture rather than a pinhole.
- Count plugs against the allowable number on the certificate — too many cost steaming capacity and the classification itself.
Surveyor follow-up: fifth tube plugged with the certificate allowing three — isolate, cut out or report to class first?
Full theory: Troubleshooting the Boiler -
27 How to extinguish boiler fire
Answer
Boiler fires die by isolation: cut the fuel, starve the air, cool the boundaries, and never open a hot fire-side door.
- Sound the alarm and inform the bridge, then restrict by shutting burners, fuel and air register and isolating the fire side.
- For an oil-fired boiler fire, use the correct extinguishing medium through the fire ports — never straight water on burning oil.
- Cool boundaries from outside and keep the water side circulating so tubes never sit below the flame temperature.
- Keep the fire side shut until completely cool; opening early admits the oxygen that turns a small fire into an uptake fire.
Surveyor follow-up: oil burner fire with the fire-side door closed and the extinguisher already discharged outside — reopen or soak first?
Full theory: Boiler Safety Devices and Emergency Response -
28 Hydrate Alkalinity test: Determines the presence of hydrates in the boiler water
Answer
The alkalinity tests read the boiler’s chemical backbone: P and T tell hydroxide and carbonate, so you know what is holding alkalinity.
- P-alkalinity reads hydroxide and carbonate; T-alkalinity reads the same plus bicarbonates, so the difference exposes the carbonate.
- Caustic or carbonate treatment holds the water alkaline; the test tells you which is doing the work.
- Low readings mean corrosion risk; high readings with carryover mean caustic gouging — one number, two dangers.
- Read the sample from the designated cooling point, and trend it against phosphate and conductivity each watch.
Surveyor follow-up: T-alkalinity high with P-alkalinity normal and carryover in the steam — carbonate, feed or blowdown first?
Full theory: Boiler Water Treatment, Testing, and Blowdown -
29 Pressure inside boiler
Answer
Pressure is steam temperature in a gauge: working pressure set below the safety valve, with accumulation and blowdown as the limits.
- Working pressure is the design figure; safety valves set only slightly above it, never more than about 3% above approved working pressure.
- Accumulation is the extra rise as the valve lifts and further compresses its own spring — typically about 10% of setting.
- Working pressure and superheat set steam temperature, which sets what the superheater and the ship can actually deliver.
- Quote the setting, the accumulation and the working pressure together, and record lift pressures in the logbook for class.
Surveyor follow-up: working pressure 7 bar with valves set 9 bar and accumulation near 10% — correct or to reset?
Full theory: Normal Operation, Load Control, and Watchkeeping -
30 Shell expansion plan ? Why it is given and framing system?
Answer
The shell plan is the plating map: strakes lettered by level, plates numbered aft to forward, over the frame layout it must also show.
- It is developed from the line plan — a two-dimensional drawing of the hull’s three-dimensional shell surface.
- Strakes are lettered by level (A at the top going down); plates are numbered from aft to forward along each strake.
- Sheer strake, side shell, bilge strake and garboard strake are the levels the surveyor expects named on it.
- It pairs with the framing plan, since every plate and seam sits on a frame, floor or girder line shown there.
Surveyor follow-up: renewal cut with strake letter and plate number from the framing plan only — acceptable, or the shell plan first?
Full theory: Ship Types, Hull Form and the Parts of a Ship -
31 Shell expansion plan in brief, i numbering starting from fwd or aft in sep
Answer
Brief version: letter by level, number from aft to forward — so a plate is found by its letter and its number, never by eye.
- Letters run A, B, C downward from the topmost strake on the ship’s side; numbers count from aft to forward.
- Each plate is therefore identified by letter plus number, exactly as the shipyard plate list and the surveyor read it.
- Steel renewal and repair work cut and mark by that pair of references with the framing plan for structure.
- If the two numbering directions are confused on a ship, say so — the surveyor’s follow-up is exactly that question.
Surveyor follow-up: forward-numbered plates claimed on a ship numbered from aft — which end, and how do you prove it?
Full theory: Ship Types, Hull Form and the Parts of a Ship -
32 Shell expansion plan,sheer strake,garbord strake,
Answer
The shell plan unrolls the hull: sheer strake at the deck edge, bilge strake round the turn, garboard strake along the keel.
- A three-dimensional hull surface is drawn two-dimensionally with all vertical dimensions taken around the girth.
- Strakes are lettered by level and plates numbered, so sheer, side, bilge and garboard are named with letter and number.
- Side and bottom plating appear as one continuous picture — the way a plate looks on the ship, not in a vertical projection.
- Draw it from the frame lines the yard used, with seams, butts, stringers and openings positioned on their strakes.
Surveyor follow-up: garboard strake identified three strakes above the keel — bilge, garboard or sheer, and how do you prove it?
Full theory: Ship Types, Hull Form and the Parts of a Ship -
33 Shell expansion plane
Answer
The shell expansion plan is the plating reference drawing: strakes lettered by level, plates numbered, the hull opened out flat.
- Developed from the line plan, showing the shell plating as a continuous two-dimensional surface around the girth.
- Letters run down the side from the topmost strake; plates are numbered along each strake, normally aft to forward.
- Carries seams, butts, frame lines, stringers and openings, so steel work is cut and recorded by reference.
- Pairs with the framing plan: the plates on the plan must sit on the frames shown there.
Surveyor follow-up: shell plan used for a repair with no plate number and no frame line — how is that repair recorded?
Full theory: Ship Types, Hull Form and the Parts of a Ship -
34 Shrinkage and swelling of boiler
Answer
Boilers breathe with heat: stays hold the shell, so expansion and contraction become bending and thermal stress in tubes and sheets.
- Heating expands the shell; cooling contracts it, and the difference between the two is what the stays and supports fight.
- Unsupported superheater elements pick up extra stress, drain badly and change gas flow — soot or tube failure follows.
- Repeated swelling and shrinkage opens tube ends, thins tubes and cracks tube plates and drum welds.
- Keep starts and stops gradual, warm the boiler through evenly, and keep stays, supports and handholes in good order.
Surveyor follow-up: tube ends weeping with rapid pressure swings in the log — thermal cycling, water chemistry or joints first?
Full theory: Troubleshooting the Boiler -
35 Tell me the perticulars of Boiler of your Ship
Also asked: “Which boiler u have on ship? Detail”
Answer
Quote the boiler as the chief would: maker, type, capacity, working pressure, evaporation, fuel and safety settings.
- Maker, model and type — auxiliary oil-fired, composite or waste-heat — with evaporation capacity in kg per hour.
- Working pressure, superheater arrangement, heating surface and number of furnaces or gas passes.
- Safety valve setting and count, with working pressure, accumulation and the last recorded lift pressures.
- Fuel burnt and burner capacity, plus the level of automation — prove you know your ship, not the class in general.
Surveyor follow-up: particulars quoted for the ship’s sister vessel — what changes, and which document settles it?
Full theory: Normal Operation, Load Control, and Watchkeeping -
36 To prevent scale formation in the boiler
Also asked: “To prevent the scale formation in the boiler and feed system fe”
Answer
Scale is hardness turned to stone: keep it out of the feed, treat what arrives, and blow the sludge away before it bakes.
- Purify the feed and remove dissolved gases so hardness never reaches the tubes in the first place.
- Phosphate treatment turns incoming hardness into non-adherent sludge instead of hard scale on the water side.
- Blow down on the chloride and conductivity tests so concentrated solids leave the boiler instead of depositing.
- Keep the feed heating and deaeration working — scale forms fastest on hot raw water carrying oxygen and hardness.
Surveyor follow-up: scale found with phosphate fed and blowdown on schedule — feed quality, temperature or sludge conditioning first?
Full theory: Boiler Water Treatment, Testing, and Blowdown -
37 Type of boiler which required more maintenance n y
Answer
The composite boiler: fire-side and water-side surfaces both exposed, so tubes need water inside and gas outside, kept clean both ways.
- Composite or three-drum designs carry generating tubes with fire inside and water outside, the worst of both worlds for cleaning.
- Soot on the fire side and scale on the water side cut heat transfer from both directions at once.
- Draught loss, tube overheating and end leaks follow long before a clean water-tube boiler gives any warning.
- Small auxiliary boilers need daily soot blowing, water-side treatment and regular tube inspections because of exactly this.
Surveyor follow-up: composite boiler with clean tubes but low steam — fuel, draught, water side or heat transfer first?
Full theory: Troubleshooting the Boiler -
38 Where a waste heat boiler is subject to persistent leakage at the tube / tube plate connection, state with reasons: (a) The possible causes of such leakage; (b) The effects of this leakage
Answer
Waste-heat leaks at the tube plate are vibration and heat fatigue: the exhaust gas is hot, the tube ends cool, and the joint cycles forever.
- Causes: thermal cycling between hot exhaust gas and cooled tube ends, vibration from the gas flow, and flexing between the tubes.
- Vibration without proper tube support sets up extra stress, alters drainage and gas flow, and works the joints loose.
- Effects: exhaust gas leaking into the casing raises casing temperature, and steam returning into the exhaust drops the engine’s power.
- Repair by expanding the tube ends, plugging where permitted, or fitting tube supports and flexible elements to stop the movement.
Surveyor follow-up: casing hot and exhaust temperature down with steam in the uptake — gas-side leak or tube-end failure first?
Full theory: Troubleshooting the Boiler -
39 Where safety valve is fitted in co2 system
Answer
CO₂ bottles carry bursting discs and quick-release valves, not steam safety valves: the release cabinets hold the pilots that open them.
- Bottle head assemblies use bursting discs and quick-release valves pierced by a cutter, not spring safety valves.
- Pilot cylinders in the release cabinet supply the gas that drives the gang release and opens the master valve.
- Discs burst on overpressure — high heat or fire in the CO₂ room — venting the room through the bursting arrangement.
- Release cabinets sit in the CO₂ room and remotely at the fire control station, in parallel with non-return valves.
Surveyor follow-up: one pilot cylinder empty with the remote cabinet proved — is the local release still available?
Full theory: CO2 Fixed Fire-Fighting System on Ships -
40 Why 2 safety valves, pressure setting of both same r not
Also asked: “Why 2 safety valves”
Answer
Two valves guard against the failure of one: both set to the same pressure, sharing load and proving the other works.
- Two are fitted so one still protects the boiler if the other sticks, is gagged or fails to lift.
- Both are set to the same lifting pressure — not staggered — so neither can pass steam at working pressure.
- One chest, two valves, keeps the number of penetrations into the pressure shell down and the shell stronger.
- Each valve lifts on test and the records go to class, so a stuck valve is found on the bench rather than on the boiler.
Surveyor follow-up: one valve gagged and the other lifted 3% high — reinstate both, reset one, or report and continue?
Full theory: Normal Operation, Load Control, and Watchkeeping -
41 With reference to auxiliary boilers; (a) Briefly describe the maintenance procedures for oil burning equipment. (5) (b) Explain the need for, and the use of, soot blowers. (5) (c) Describe how a boiler should be taken ou
Also asked: “With reference to auxiliary boilers; (a) Briefly describe the maintenance procedures for oil burning equipment. (5) (b) Explain the need for, and the use of, soot blowers. (5) (c) Describe how a boiler should be taken out of service. (6”
Answer
Auxiliary boiler upkeep is burners clean, gas side blown, and shutdown gradual — cold shocks crack what soot only insulates.
- Oil equipment: clean burners and tips, keep oil at proper temperature, and prevent water in the oil that kills flame and panters.
- Soot blowers keep gas-side surfaces clean so deposits cannot insulate, corrode or start the uptake fire.
- Take the boiler out by banking the fire, stopping feed, and cooling slowly — never a cold-water quench on hot tubes.
- Drain and inspect the fire side and water side after cooling, with the soot blower and safety valves proved before firing again.
Surveyor follow-up: boiler out for tube plug with soot blower run cold — which came first, and what did the tubes show?
Full theory: Normal Operation, Load Control, and Watchkeeping -
42 boiler safety cuts
Also asked: “Boiler cut offs”
Answer
Safety cuts are the burner’s last line: low water, high pressure, failed flame and air failure stop the fire before the boiler is hurt.
- Low-water cut-off stops the burners when the level drops below the set point, independent of the working control.
- High-pressure cut-off stops the fire at the safety-valve setting, and flame failure stops it if the flame is lost.
- Air-pressure failure and high-level alarms stop or warn, so a failed fan or pump cannot fire the boiler into a fault.
- Test each cut on schedule with the burner running — a cut never proved is a cut that does not exist.
Surveyor follow-up: low-water cut bypassed with a stuck feed valve on the same board — reinstate the cut or prove the valve first?
Full theory: Boiler Safety Devices and Emergency Response -
43 boiler soot blow
Also asked: “Boiler soot blowing and or”
Answer
Soot blowers keep the gas side clean: rotating nozzles in a heat-resistant chest strip deposits before they insulate and corrode.
- Fitted to hold gas-side heating surfaces clean and prevent deposit build-up that leads to corrosion and uptake fires.
- A head or chest with nozzles on a heat-resistant tube or spindle, rotating and retracting under an operating mechanism.
- Efficiency comes from turning pressure energy into a high-velocity jet across the sooted surface, not from volume of air.
- Blow down first, never cold, and never with the burner alight — cold water into a hot tube is the fastest way to crack it.
Surveyor follow-up: soot blower called with the burner alight and tubes cold — blow, stop the fire, or postpone?
Full theory: Troubleshooting the Boiler -
44 pH of boiler water
Answer
Boiler water runs alkaline — roughly 10.5 to 11 on the pH scale — because acid corrosion there is the fastest way to destroy a boiler.
- The working range is about 7.5 to 14.0 for boiler water and 6.5 to 10.0 for condensate, measured on a cooled sample.
- Alkalinity protects the magnetite film; acid water strips it and the steel pitting follows within weeks.
- The reading sets the chemical dose, so drifting pH is treated at the dosing stage, not blamed on the water later.
- Test from the designated cooling point, with the sample cooled, and trend it against phosphate and conductivity each watch.
Surveyor follow-up: pH 9.5 in the boiler with the feed proved alkaline — dosing, blowdown or test error first?
Full theory: Boiler Water Treatment, Testing, and Blowdown -
45 what was the normal operating pressure of your boiler?
Also asked: “• what was the normal operating pressure of your boiler?”
Answer
Quote the ship’s own figures, then the settings: working pressure, valve setting, accumulation and superheat.
- State the approved working pressure first — the number on the certificate and the safety valve setting for that boiler.
- Give the setting just above working pressure, and the allowed accumulation above that setting.
- Add superheat temperature and evaporation capacity so the answer describes a boiler, not a rule.
- If you do not know the ship’s figure, say so and give the range — inventing a number is what fails the oral.
Surveyor follow-up: working pressure quoted above the safety valve setting — which is wrong, and what does the class say?
Full theory: Normal Operation, Load Control, and Watchkeeping
Source: 123 written papers and surveyor oral banks, 24,613 entries, merged into 17,210 topics. Ticks are stored on this device only.