Boiler condition survey

Institute of Maritime
Upgrading Studies
Engineering Studies
Machinery Condition Survey
Boiler Survey
Yasser B. A. Farag
MSc. in Maritime Energy Management
World Maritime University - WMU
Malmo, Sweden

Eng. Yasser Bayoumy 3Machinery Survey14/07/2020
Reasons and aims of surveys

Reference!

Types of surveys

Reference SOLAS, CH. II-1, Reg. 32

The survey covers:
Boiler Survey
1. Internal examination of the water-steam and fire side, which includes functional testing of safety valves
Guidance note: On small boilers and/or units fitted with steam generating coils / tube panels making internal
examination un-practicable, the internal examination may be substituted by hydraulic pressure testing at 1.5 times
the design pressure.
2. External examination
examination of mountings and fittings, including safety valves, pressure, level and temperature transmitters for
control and monitoring. Opening up as found necessary by he surveyor
• review of the following records since the last survey: Operation, maintenance, repair history, boiler water
management.
• verification of the safety valve setting
• examination and testing of the operation / function of safety valve relieving gear.
IACS Req. 2001/Rev.8 2018

• Water tube boilers used for main propulsion, including reheat boilers, all other boilers of
essential service, and boilers of non-essential service having working pressure exceeding
0.35 N/mm2 (3.5 bar) and a heating surface exceeding 4.5 m2, are to be surveyed internally.
• There is to be a minimum of two internal examinations during each 5-year special survey
period. In all cases the interval between any two such examinations is not to exceed 36 months. An
extension of examination of the boiler of up to 3 months beyond the due date can be granted in
exceptional circumstances**.
Boiler Survey
** "Exceptional circumstances" means unavailability of repair facilities, unavailability of essential materials, equipment or spare parts,
or delays incurred by action taken to avoid severe weather conditions.

• At each survey, the boilers, superheaters, and economizers are to be examined internally on water-
steam side and fire side.
• Boiler mountings and safety valves are to be examined at each survey and opened out as considered
necessary by the Classification Society.
Boiler Survey
** "Exceptional circumstances" means unavailability of repair facilities, unavailability of essential materials, equipment or spare parts,
or delays incurred by action taken to avoid severe weather conditions.

• When direct visual internal inspection is not feasible due to the limited size of the internal spaces, such as for
small boilers and/or narrow internal spaces, this may be replaced by a hydrostatic pressure test or by
alternative verifications as determined by the Classification Society.
• The adjustment of the safety valves is to be verified during each boiler internal survey.
• Boiler safety valve and its relieving gear are to be examined and tested to verify satisfactory operation.
However, for exhaust gas heated economizers, if steam cannot be raised at port, the safety valves may be set
by the Chief Engineer at sea, and the results recorded in the log book for review by the Classification Society.
• Review of the following records since the last Boiler Survey is to be carried out as part of the survey:
1. Operation
2. Maintenance
3. Repair history
4. Feedwater chemistry
Boiler Survey IACS Req. 2001/Rev.8 2018

• External survey of boilers including test of safety and protective devices, and test of safety valve using its
relieving gear, is to be carried out annually, within the window of the Annual Survey of a ship.
• For exhaust gas heated economizers, the safety valves are to be tested by the Chief Engineer at sea within the
annual survey window. This test is to be recorded in the log book for review by the attending Surveyor prior
to crediting the Annual Survey of Machinery.
• An extension may be granted by the Classification Society after the following is satisfactorily carried
out:
i) External examination of the boiler
ii) Boiler safety valve relieving gear (easing gear) is to be examined and operationally tested
iii) Boiler protective devices operationally tested
iv) Review of the records since the last Boiler Survey:
Boiler Survey IACS Req. 2001/Rev.8 2018

Survey items :
Boiler Survey
1. All mountings to be opened up and surveyed.
2. Fuel oil burning system , valves and piping system
3. Pressure gauge and water level indicators
4. Safety valves
5. Collision chocks , seating stools and stay bolts to be examined.
6. Safety devices fitted on boiler and alarm test.

Annual Boiler Survey
• Hydraulic testing (1.25 x approved working pressure for not more than 10 minutes).
• Pressure testing of main steam piping at 15% in excess of approved working pressure for not more than 10 minutes.
• Internal inspection, hammer test to furnace, stays bolts, fire and stay tubes, brickwork, baffles and casing.
• Inspection of alarm and control system, fuel system, feed system, all steam piping and lagging arrangement,
foundation and chocking system.
• Checking of pressure gauge and water level gauges.
• Testing of safety valves to blow off at the pressure not greater than 3% above w.p.
• After 10 years old or at any time, if surveyor demands, drill test near the water line should be done to determine
actual thickness of boiler shell If found necessary, lower working pressure may be reassigned
At 4 years interval:
• In addition to above Annual inspection procedure, all valves on boiler required to open-up and inspected,
every 4 years at the time of Annual Survey, or at the next regular dry docking period thereafter.

Owner's duties prior to survey:
Boiler Survey preparations
• Cleanliness of boiler on both water and gas sides shall be ensured to a condition required to assess
structures
• Boiler to be completely isolated/secured from live steam systems, cooled down and opened up to give
access to both steam/water and fire/gas sides. Hand-hole covers on headers/at bottom of water space shall
be opened up to facilitate internal examination. Boiler armatures shall be readied for opening up
• Boiler to be well ventilated on both steam/water and fire side. Safe work lighting to be provided.
DNV-GL,Pt.7 Ch.1 Sec.5

Scope of High-Pressure Boiler Inspections
Inspectors should always review past inspection reports and any design documents available for the high-
pressure boiler prior to initiating an inspection. An inspection includes a thorough examination and analysis of
both waterside and fireside surfaces, and inspections may also include economizers, feedwater heaters,
deaerators, and other related equipment.
Inspectors look for evidence of corrosion, leaks and cracks, deposits and plugging, and any other damage, taking
photos of all damage and potential concerns and also discussing all concerns in the written report. Inspectors
also verify the functional efficacy of operational and safety controls.

Preparation for survey:
• Shut down the boiler and gradually cold down.
• All steam valves tight shut
• Carry out bottom blow down properly
• When the boiler pressure in near to ATM pressure , open the boiler vent valve , sight glass drain cock , salinometer
cock to prevent the vacuum effect.
• Lift the safety valve by easing gear
• Top man door open first and when open bottom man hole use the crow bar and stand clear away because hot water
may left inside.
• When boiler cold enough , Clean water and firesides.
• All of the boiler mountings to be overhauled and displayed for survey.
• Gags or clamps must be prepared for safety valves.

Preparation for survey
• Boiler must be filled with water at a temperature not more than 38° C for fire tube boiler and not more than 82° C
for water tube boiler.
• Drip pan placed under all burners.
• Tank top and bilges cleaned.
• Pump for pressure test to be kept ready.
• Blanks must be installed at steam valves and water level gauge

Eng. Yasser Bayoumy 19Tuesday, July 14, 2020
Fuel Air
Basic Steam Power Plant
Boiler
Feed water
pump
Steam
Turbine
Condenser
Super
heater
Heating
Hot well tank
Cooling
water in
Cooling
water out
Wet steam
Drysteam
Feedwater
Condensate
water
+90 C
M W
Machinery Survey

Eng. Yasser Bayoumy 20
Boilers Classification
According to use:
Main
Auxiliary
According to passage of flue gases:
Water tube
Fire tube
According to heating source:
Oil fired
Exhaust gas
Composite
Tuesday, July 14, 2020 Machinery Survey

Composite Cochran Boilers

Water tube boiler

Exhaust Gas Boiler

Common Boiler Fittings

Sight glass

Safety Valve
• The Safety valve must never be less than 38 mm in diameter (D), and the area (A) of the
valve can be calculated from the following formula:
H: Total heating surface (𝑚𝑚2
)
E: Evaporative rate kg/ 𝑚𝑚2
P: Safety valve working pressure
A: Aggregate area through the seating of the valve 𝑚𝑚𝑚𝑚2
C: Discharge coefficient whose value depends upon the type of valve.
• Ordinary valve => C=4.8, lift=𝐷𝐷𝑂𝑂𝑂𝑂𝑂𝑂/24
• High lift valve => C=7.2, lift= 𝐷𝐷𝐻𝐻𝐻𝐻 /12
• Improved high lift valve => C=9.6, lift= 𝐷𝐷𝐼𝐼 𝐼𝐼𝐼𝐼 /4
• Full lift valve => C=19.2
𝑫𝑫𝑶𝑶𝑶𝑶𝑶𝑶 > 𝑫𝑫𝑯𝑯𝑯𝑯> 𝑫𝑫𝑰𝑰𝑰𝑰𝑰𝑰

Eng. Yasser BayoumyTuesday, July 14, 2020
Boiler safety valves
Ordinary spring loaded safety valve High-lift spring loaded safety valve Improved High-lift safety valve
• Winged valve
• No waste steam piston
• Winged valve
• Waste steam piston
• No floating ring
• Wingless valve
• Waste steam piston
• Floating ring
28Machinery Survey

Safety Valve

Water Chemistry
Hardness salts
Temporary
Alkaline salts
Hydroxides, Carbonates and
Bicarbonate of calcium and
magnesium
With heating to boiling point it will
decompose and liberating CO2
Permanent
Non-alkaline salts
Chlorides, Sulphates,
Nitrates and Silicates
When heated to the boiling
temperature, will cause acidity
Scales Corrosion
Corrosion
Machinery Survey

• Dissolved solids in fresh waters vary considerably depending on the source of the water
• The various solids listed above will react in different ways when subjected to heat and
pressure within a boiler.
Water Chemistry
Machinery Survey

• Temporary Hardness salts: these are alkaline salts: i.e.,
hydroxides, carbonates and bicarbonates of calcium and
magnesium. These salts will decompose when the water is heated
to boiling point, liberating carbon dioxides and leaving carbonate
scales.
• Permeant Hardness salts: These are non-alkaline salts i.e.
chlorides, sulphates, nitrates and silicates. Permanent hardness is
not removed by heating the water to boiling point but will cause
problems with scale and acidity as the water is further heated.
• Total Hardness: the sum of temporary and permanent hardness
salts. It’s an indication of the total scale forming potential in the
water.
Water Chemistry
Machinery Survey

Water Chemistry
Type Impurity Problem caused
Gaseous
Dissolved Oxygen Pitting Corrosion
Carbon Dioxide Condensate Corrosion
Soluble
Calcium / Magnesium Scaling
Sodium / Potassium Corrosion
Chloride / Sulfate Corrosion
Carbonates / Bicarbonate Scaling / Foaming
Hydroxides Scaling / Foaming
Silica Scaling / Deposition
Insoluble Suspended solids Fouling
Others Oils / Organics Foaming / Carryover
Machinery Survey

Boiler Water treatment
Lime & Soda
Used for Low pressure
boilers
Calcium hydroxide removes
the temporary hardness
High TDS in water =>
foaming and carry-over =>
constant blow-down is
necessary => uneconomical
Phosphate – Sodium
Hydroxide
Now used for all group of
boilers
The end result is insoluble sludge
(calcium phosphate &
magnesium phosphate) and
soluble sodium chloride and
sodium sulphate
TDS should be monitored and
regular blow-down to maintain
TDS levels.
Sludge may build up in headers
which will impede thermal
circulation => overheating => tube
failure
Combination treatment
• A chemical mixture
• Simple and convenient
• Precise and simple instructions to
use
• Consists of sodium carbonate and
sludge conditioning agents
• Antifoam
• Hydrazine and oxygen scavengers
added to condensate water
Machinery Survey

Boilers’ water treatment
Boiler water treatment
Chemical
Anti scales
Oxygen
scavengers
Corrosion
prohibitors
Cleaning heat
transfer surfaces
Natural
Cleaning heat
transfer surfaces
Blowing down
and Scumming
Machinery Survey

Safety Valve
Hydraulic Test
• Before 12th year (1.25xP) if P < 40
(1.20xP)+2 if P > 40
• After 12th year (1.15xP) whatever P value

Eng. Yasser Bayoumy 39
Tuesday, July 14, 2020
Fuel Air
Water problems in Boiler system
Boiler
Feed water
pump
Steam
Turbine
Condenser
Super
heater
Heating
Hot well tank
Cooling
water in
Cooling
water out
Wet steam
Drysteam
Corrosion / Scaling/overheating
Carryover
Corrosion
Corrosion
Feedwater
Condensate
water
CO2O2 + Oil
• Oxidation
• Galvanic corrosion
• Caustic Embrittlement
• Thermal stresses
• Mechanical strain
• Oil
• Metal
• Water
• TDS
+90 C
Machinery Survey

Causes of Boiler Corrosion
1- Oils
Lubricating oils may contaminate the feed system and find their way into the boiler, this could be caused due to over
lubrication of machinery and inefficient filtering of the feed. Oil can decompose in the feed water boiler liberating
their fatty acids, these acids can cause corrosion. Hence it is advisable to use pure mineral oil for lubrication of
machine parts where contamination of feed can result, but oil of any description should never be allowed to enter
the boiler as it can adhere to the heating surfaces causing overheating. It can also cause priming due to excessive
ebullition.
2- Mechanical Straining
Mechanical straining of boiler parts may be due to mal-operation of the boiler, raising steam too rapidly from cold,
missing or poorly connected internal feed pipes, fluctuating feed temperature and steaming conditions. Grooving is
caused through mechanical straining of boiler plates, and where a groove is present there is always the danger of
corrosion resulting in the groove.
Machinery Survey

Causes of Corrosion
3- Galvanic Action
When two dissimilar metals are present in a saline solution galvanic
action may ensue, resulting in the corrosion of the more base metal. Zinc
for example would serve as an anode to iron and iron would serve as an
anode to copper. Sacrificial anodes are frequently used to give cathodic
protection. In Scotch boilers zinc plates are sometimes secured to
furnaces and suspended between tube nests, these act as sacrificial
anodes giving cathodic protection to the steel plating, etc., of the boiler.
Corrosion of non-ferrous metals in steam and condensate systems may
result in deposits of copper on boiler tube surfaces (known as 'copper
pick up'), which due to galvanic action can lead to boiler corrosion.
Machinery Survey

Causes of Corrosion
4- Caustic Embrittlement
The phenomena of caustic embrittlement (or intercrystalline fracture) is
believed to be caused by high concentrations of caustic soda (Sodium
hydroxide NaOH) and the material under stress. The stress corrosion
cracks follow the grain or crystal boundaries of the material and failure of
the affected part could result. Concentrations of sodium hydroxide
required for embrittlement to occur vary with operating conditions,
roughly about 102.7 kg/m3 at 300°C is a guide to the amount of
concentration required. Normally such concentrations would never be
found in a boiler, but, leakages at rivet heads, seams and boiler
mountings, etc., whereby water is flashed off to steam, leaving behind
the solids locally, can cause the high concentrations required.
Machinery Survey

Causes of Corrosion
Machinery Survey

Causes of Corrosion
Sodium hydroxide depresses the solubility of sodium sulphate, and sodium
sulphate can therefore be made to precipitate. Use is made of this fact to give
protection against caustic embrittlement. When concentrations of sodium
hydroxide are high and sodium sulphate is present, the sodium sulphate can
precipitate and form a protection for the material.. It is recommended that the
ratio of sodium sulphate to caustic soda should not fall below 2.5 at all times.
Other substances that have been used as inhibitors against caustic embrittlement
are, quebracho tannin and sodium nitrate. Caustic corrosion in high pressure
boilers is usually indicated by gouging of the tubes and is caused by excess
sodium hydroxide and a concentrating mechanism. This phenomenon results
in the destruction of the protective magnetic oxide of iron film (Fe04) and
the base metal is then attacked by the concentrated sodium hydroxide.
Machinery Survey

Silicate
Machinery Survey

SOME DEFECTS FOR AUXILIARY BOILERS
Deformation
With cylindrical furnaces, this can be determined by sighting along the furnace or by use of a lath swept around the
furnace or by furnace gougings. The causes of deformation are: scale, oil, sludge or poor circulation, resulting in
overheating of the furnace and subsequent distortion. Local deformations could be repaired by cutting through the
bulge, heating and pressing back the material into the original shape, and then welding. By cutting through the bulge
prior to heating and pressing facilitates flow of metal during pressing. Alternatively, the defective portion could be cut
out completely and a patch welded in its place. If the furnace is badly distorted then the only repair possible may be
renewal
Wastage
The causes of wastage are corrosion and erosion. If it is great in extent then renewal of the furnace may be the only
solution. Localised corrosion could be dealt with by cutting out the defective portion of furnace and welding in a new
piece of material.
Machinery Survey

SOME DEFECTS FOR AUXILIARY BOILERS
Cracks
Circumferentially around the lower part of the connecting necks cracks may be found. These cracks are caused by
mechanical straining of the furnace and the defect is generally referred to as grooving. If the groove is shallow
compared to plate thickness (depth can be ascertained by drilling or by ultrasonic detection) it is usual to cut out the
groove and weld. However, if the grooving is deep the material is cut right through and welded from both sides.
Cracks, due to overheating, may be found where deformation has occurred, these must be made good in the
manner described above.
Machinery Survey

Refractory
• A refractory material is one that retain its strength and not fuse at high temperatures.
• “non-metallic materials having those chemical and physical properties that make them
applicable for structures, or as components of systems, that are exposed to
environments above 538 C.
• Example: Fire clay, Silica, Chromite magnesite
• Refractory bricks are bricks that can withstand high temperatures
• A block of refractory ceramic material
• Should not spall under rapid temperature change, and their strength should hold up
well during rapid temperature changes.
• Dense firebricks are used in applications with extreme mechanical chemical or thermal
stresses
• In other, less harsh situations, more porous bricks are used.
Machinery Survey

Refractory failure
SPALLING ‫اﻟﺗﻛﺳﯾر‬
This is the breaking away of layers of the brick surface. It
can be caused by fluctuating temperature under flame
impingement or firing a boiler too soon after water washing or
brick work repair.
May also be caused by failure to close off air from register
outlet causing cool air to impinge on hot refractory.
SLAGGING ‫اﻟﺧﺑث‬
This is the softening of the bricks to a liquid state due to the
prescience of vanadium or sodium ( ex sea water ) in the fuel.
This acts as fluxes and lowers the melting point of the bricks
Flame impingement may lead to carbon penetrating refractory.
Machinery Survey

Refractory failure
SHRINKAGE CRACKING
Refractories are weaker in tension than in compression or
shear thus, if compression takes place due to the expansion
of the brick at high temperature , if suddenly cooled
cracking may occur.
Failure of brick securing devices
Machinery Survey

Boiler Fires
• Fires:
Good combustion conditions will minimise the risk, deposits allowed to accumulate in this area are a fire
risk and, should fire take hold undetected.. There is plenty of evidence of soot fires leading on to hydrogen
fires.
1. Soot Fires:
The ignition of an accumulation of soot, rich in carbon, caused by poor combustion either in ort
or when operating at low power for prolonged periods, can when supplied with the necessary
oxygen be the source of a fire sufficiently intense to melt and burn steel.
2. Hydrogen Fires:
When overheating of a superheater due to insufficient steam circulation is very severe, the tube
material may ignite at about 700°C and, burning in the steam, produce free hydrogen. The iron
will continue burning independently of any supply of oxygen from the air, and the hydrogen
produced by the reaction will burn on coming into contact with air. This means that once such a fire
has started there are likely to be two fires burning simultaneously, one, iron burning in steam and
the other, hydrogen burning in air, the combined fire being self supporting and probably lasting
until the supply of steam is exhausted.
Machinery Survey

The Failure- Case study
Machinery Survey

Machinery Survey

Cause of the failure
Machinery Survey

Machinery Survey

Boiler condition survey

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