Exam Question Flashcards
how to tackle a maintenance task
all aspect of the job to be considered. factors to be considered are:
1. equipment availability
2. time required
3. extent of task
4. user requirement’s
5. ship operational requirements
6.tag out
7. Job plan
8. Spares required
9. Tools required
What is chemical corrosion
when unprotected metal is exposed to the atmosphere. and the metal reacts with oxygen to form oxides, such as rust on steel
How is corrosion accelerated
MOISTURE, ATMOSPHERIC POLLUTION such as acid,
HEAT
How to prevent corrosion
Choice of metals
Good design
Cathodic protection
Protective coating
Why do we use different metals
For Strength
Resistance to corrosion
Resistance to erosion
Resistance to wear
Bearing capacity
What techniques can we use on seized fastenings
Easing fluids (oils, px24)
locknuts
stud extractor
stud box
heating/ burning
hacksaw
What is a helicoil set and how do we use it
if a internal thread has been damaged it can be reclaimed by using a thread insert.
to use it you drill the hole oversized with a dedicated helicoil tap and inserting a Monel metal insert
Advantages of helicoils
material is none-corrosive
relatively quick and simple method of repair
keeps the stripped thread holes to the original size
Why do we use jointing/gaskets
seals on poor tolerance faces
seal slight defects on faces
prevent egress or ingress of foreign matter
With reference to spiral wound gaskets what information is stamped on it?
the nominal size
the NSN
the makers name or trademark
class
What does CHS mean?
critical hole size
What does SHS mean ?
specified hole size
What surveys are carried out on a maintenance schedules
propulsor/propeller
sea tubes
ballast tanks
What is hydrostatic test designed to do??
to prove the integrity of a valve
to prove the integrity of the fasteners
to demonstrate the leak tightness of the valve seat
to demonstrate the leak tightness of major pressure hull structures
What pressure are escape towers system tested to that are critical for DSRV
Are tested to 110% DDSTP
When replacing a mount where would you get the information for replacing?
BR 3021 Vol 2
Map 01-473 Date book
Explain J mounts
there used for shock protection of electrical equipment. fitted to electrical equipment fitted to bulkheads
Explain a L mount
the L mount isolates vibration as well as giving protection against shock. The accelerator unit is boned and the decelerator is spigoted
Explain M mounts
A larger version of L mounts which come in only size.
What is P/PD mount and what should it be used in conjunction with
Fitted to diesel engines and need to be fitted with acceleration and deceleration mounts
normal and relief stages on a compressor
normal stage pressure relief pressure
1st 3bar 3.8
18bar 21
83bar 100
276 304
Explain main lubrication system on HPAC
a forced lubrication system conveys oil.to the big end bearing, main bearing and crankshaft passages. the con rod is drilled to supply oil to the small end bearing bushes
what is the objective of NDT
To achieve the maximum reliability of materials, equipment and system
to reduce long term servicing costs
to minimise wastage in skilled labour and costly materials
what can NDT show?
thickness of the material
show the extent and position of the defect
enable the condition of equipment to be ascertained without disassembly
why do we carry out dye flaw detection and how
dye flaw detection is a method of detecting surface breaking flaws
1. surface preparation and drying
2. application of penetrant
3. removal of surplus and drying
4. development
5. examination and interpretation or indication
removal of test material
What is impingement?
Impingement is the accelerated corrosion/erosion arising from the continual removal of the protective oxide film from the inside of the pipe wall by turbulent water
Closing up at machinery
- Ensure no bits left over
- Clean down equipment
- Prove all oil pipes clear, before fitting
- Turn machine several times by hand to make sure that nothing is preventing turning
When inspecting mounts . What are you looking for
Look for paint, oil and fuel contamination. Signs of distortion, damage, misshaping
Properties required for heat exchange
- Overall heat transfer
- Corrosion Resistance
- Strength/weight
- Ease of manufacture
- Cost
- Erosion Resistance
