Boilers and Pressure Vessels MCQs 2026

Relief valve on pressure vessel protects against

1. A only underpressure vacuum collapse always without valve ✓
2. B only mechanical vibration ✓
3. C overpressure from process upset or thermal expansion ✓
4. D only misalignment of flanges cosmetic ✓

Rupture disc provides

1. A only slow adjustable control ✓
2. B only flow regulation throttling always ✓
3. C only vacuum support only without burst ✓
4. D non-reclosing overpressure relief for rapid excursion ✓

Vacuum breaker on vessel prevents

1. A only overpressure burst ✓
2. B only excess temperature ✓
3. C only noise ✓
4. D collapse due to internal vacuum during cooling or pump-out ✓

Heat exchanger classified as pressure vessel when

1. A only if painted blue ✓
2. B only if vertical orientation ✓
3. C shell or tubes exceed pressure limits per code ✓
4. D never in any service ✓

Manhole on boiler drum allows

1. A internal inspection and maintenance access ✓
2. B only steam outlet to turbine ✓
3. C only fuel injection ✓
4. D only continuous blowdown line only ✓

Soot blower in boiler cleans

1. A heat transfer surfaces of ash deposits in flue gas path ✓
2. B only feedwater resin bed ✓
3. C only turbine blades in condenser ✓
4. D only lubricating oil filter ✓

Fluidized bed combustion boiler burns fuel in

1. A only stagnant pile without air ✓
2. B bed of hot particles suspended by upward air flow ✓
3. C only pure oxygen without fuel ✓
4. D only water mist ✓

Waste heat boiler recovers heat from

1. A only solar PV panels ✓
2. B only wind kinetic energy directly ✓
3. C exhaust gases of process or engines without separate furnace ✓
4. D only hydro penstock ✓

Package boiler is

1. A only field-erected utility boiler always ✓
2. B only domestic kitchen kettle ✓
3. C only hydraulic power pack ✓
4. D factory-assembled unit shipped ready for site connection ✓

Differential pressure across boiler circulation loop drives

1. A only electromagnetic radiation ✓
2. B only acoustic resonance ✓
3. C only colour change ✓
4. D natural or assisted water circulation ✓

Carryover of solids with steam can cause

1. A improved turbine efficiency always ✓
2. B zero maintenance need ✓
3. C turbine blade deposits and erosion ✓
4. D better lubrication of bearings ✓

Phosphate treatment in boiler water maintains

1. A acidic corrosion promotion deliberately ✓
2. B alkaline pH and sequesters hardness ✓
3. C only oil emulsion ✓
4. D only chlorine gas injection always ✓

Dissolved oxygen in feedwater causes

1. A pitting corrosion of steel boiler components ✓
2. B protective oxide always beneficial unlimited ✓
3. C higher steam purity always ✓
4. D automatic descaling ✓

Boiler efficiency on HHV basis accounts for

1. A latent heat in water vapour from combustion in flue gas ✓
2. B only sensible heat ignoring vapour ✓
3. C only radiation to sky at night only ✓
4. D only ash mass ✓

Stack temperature indicates

1. A only wind speed ✓
2. B heat lost with flue gases; lower improves efficiency if not condensing limit ✓
3. C only coal particle size only ✓
4. D only feed pump power only ✓

Combustion control maintains

1. A only maximum air always wasteful ✓
2. B zero oxygen in flue always ✓
3. C fuel-air ratio for safe efficient firing ✓
4. D only manual coal shovel rate without feedback ✓

Three-element drum level control uses

1. A only colour of flame ✓
2. B only ambient humidity office ✓
3. C only coal pile height visual ✓
4. D steam flow, feedwater flow and drum level ✓

Shrink and swell phenomenon in drum level during load change is due to

1. A only gauge glass leak ✓
2. B only chemical dosing colour ✓
3. C only soot deposit ✓
4. D bubble volume change in risers under pressure change ✓

Pakistan industrial boilers commonly use fuels such as

1. A only liquid nitrogen ✓
2. B only helium ✓
3. C natural gas, furnace oil, coal and bagasse ✓
4. D only distilled water as fuel ✓

Inspection of boiler in Pakistan typically involves

1. A only self-certification without records always ✓
2. B regulatory authority and certified inspector per safety rules ✓
3. C only painting colour check ✓
4. D only operator verbal report ✓

Accumulation test of safety valves verifies

1. A valves lift and relieve at set pressure without undue delay ✓
2. B only colour of valve paint ✓
3. C only weight of valve cap ✓
4. D only serial number font ✓

Creep in boiler tubes at high temperature requires

1. A material selection and wall thickness for long-term rupture strength ✓
2. B only room temperature tensile test data alone ✓
3. C only paint coating ✓
4. D only shorter diameter only without stress ✓

Dissimilar metal welds in boilers need attention to

1. A only aesthetic bead profile ✓
2. B thermal expansion mismatch and galvanic corrosion ✓
3. C only shortest weld length always weakest ✓
4. D only lowest cost filler always without spec ✓

Boiler cold startup requires

1. A instant full firing always ✓
2. B zero ventilation ✓
3. C controlled heating rates to avoid thermal shock and uneven expansion ✓
4. D immediate full load on turbine ✓

Retention time in steam drum allows

1. A only fuel combustion ✓
2. B only ash fusion ✓
3. C only compressed air storage ✓
4. D water droplets to separate from steam by gravity and internals ✓

A boiler is a closed vessel in which

1. A water or other fluid is heated under pressure to generate steam ✓
2. B only air is compressed for tyres only ✓
3. C only fuel is burned without heat transfer purpose ✓
4. D only water is stored at atmospheric pressure only ✓

Water tube boiler has

1. A only fire through large diameter tubes in water pool exclusively always ✓
2. B no steam generation ✓
3. C water and steam flowing inside tubes heated externally by gases ✓
4. D only condenser function ✓

Babcock and Wilcox boiler is

1. A vertical fire tube domestic only ✓
2. B only once-through supercritical without drums always ✓
3. C only hydraulic pump ✓
4. D water tube boiler with inclined tubes and chain grate or pulverized firing ✓

Locomotive boiler is

1. A only nuclear pressurizer ✓
2. B horizontal fire tube boiler with smokebox and firebox ✓
3. C only refrigeration evaporator ✓
4. D only hydraulic intensifier ✓

Economiser in boiler heats

1. A feedwater using flue gas waste heat before entering drum ✓
2. B only combustion air leaving stack directly ✓
3. C only steam after turbine ✓
4. D only cooling tower water ✓

Superheater adds

1. A latent heat at constant pressure saturation only ✓
2. B sensible heat to steam above saturation temperature ✓
3. C water subcooling only ✓
4. D only compressed air ✓

Reheater in power boiler

1. A condenses steam to water only ✓
2. B only heats feedwater ✓
3. C reheats steam between turbine stages ✓
4. D only cools flue gas ✓

Boiler drum (steam drum) serves to

1. A only store fuel oil ✓
2. B only filter feedwater chemically without separation ✓
3. C only measure stack opacity ✓
4. D separate steam from water and provide circulation head ✓

Natural circulation boiler relies on

1. A only forced pump without density head ever ✓
2. B only compressed air lift ✓
3. C only electromagnetic pump ✓
4. D density difference between downcomer and riser ✓

Forced circulation boiler uses

1. A only gravity without any pump always ✓
2. B only steam jet ejector for combustion ✓
3. C pumps to ensure adequate water flow through tubes ✓
4. D only manual bucket feed ✓

Blowdown in boiler removes

1. A only flue ash from stack ✓
2. B concentrated dissolved solids from drum water ✓
3. C only lubricating oil from bearings ✓
4. D only compressed air moisture trap water only ✓

Boiler feedwater treatment aims to prevent

1. A scale, corrosion and carryover ✓
2. B only increasing dissolved oxygen always ✓
3. C only colour of flame green always ✓
4. D only noise in turbine ✓

Foaming in boiler water leads to

1. A higher purity steam always ✓
2. B zero dissolved solids ✓
3. C wet steam and possible damage to superheater and turbine ✓
4. D automatic efficiency gain ✓

Safety valve on boiler is set to relieve at

1. A zero pressure always ✓
2. B vacuum only ✓
3. C only after catastrophic rupture without opening ✓
4. D maximum allowable working pressure (plus margin per code) ✓

Two or more safety valves on boiler provide

1. A only decorative appearance ✓
2. B only flow measurement ✓
3. C only feedwater heating ✓
4. D redundancy and capacity per code requirements ✓

Maximum continuous rating (MCR) of boiler is

1. A minimum turndown only ✓
2. B maximum sustained steam output under design conditions ✓
3. C cold startup rate only ✓
4. D blowdown volume only ✓

Boiler turndown ratio is

1. A ratio of maximum to minimum stable firing rate ✓
2. B only stack height to width ✓
3. C only tube count to drum diameter only ✓
4. D only ash fusion temperature ✓

Excess air in combustion should be

1. A enough for complete combustion but minimized for efficiency ✓
2. B infinite always ✓
3. C zero always without stoichiometric balance ✓
4. D only measured by boiler colour alone ✓

Indian Boiler Regulations (IBR) and ASME codes govern

1. A only textile weaving patterns ✓
2. B design, fabrication and inspection of boilers in respective jurisdictions ✓
3. C only road traffic signals ✓
4. D only computer software licensing only ✓

Hydrostatic test of boiler is performed at

1. A zero pressure vacuum only ✓
2. B atmospheric only without water ✓
3. C pressure above design per code (e.g. 1.5 times design) ✓
4. D only during full power generation ✓

Pressure vessel is

1. A only open water tank without lid ✓
2. B only conveyor belt ✓
3. C only gear coupling ✓
4. D container designed to hold gas or liquid at pressure substantially different from ambient ✓

Thin cylinder hoop stress formula is

1. A σ = p t / r inverted ✓
2. B σ = p r² only without t ✓
3. C σ = zero always ✓
4. D σ = p r / t ✓

Factor of safety on pressure vessel design uses

1. A only aesthetic margin ✓
2. B allowable stress below material yield or ultimate per code ✓
3. C only paint thickness ✓
4. D only bolt count decorative ✓

Weld joint efficiency in pressure vessel accounts for

1. A reduced strength due to welding compared to seamless ✓
2. B only paint colour ✓
3. C only surface roughness aesthetic ✓
4. D only shipping weight ✓

Non-destructive testing of pressure welds commonly uses

1. A radiography and ultrasonic examination ✓
2. B only colour vision test of operator ✓
3. C only hammer sound on wood ✓
4. D only weighing vessel empty ✓

Corrosion allowance in vessel thickness adds

1. A only decorative coating thickness marketing ✓
2. B extra material for expected metal loss over life ✓
3. C zero always by code mandate ✓
4. D only insulation thickness as metal ✓