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26 Cards in this Set
- Front
- Back
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What instruction covers chemical hazards encountered in salvage
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Salvage Safety Manual
(S0400-AA-SAF-010 |
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True or False
You should never attempt to speed up cutting by creating a fire or inferno deep inside the metal. |
True
such a situation could lead to an explosion |
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What is the most hazardous location a diver can be placed during cutting/welding operations
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The splash zone
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True or False
It is acceptable to bring a cutting torch into a bell with the oxygen or welding generator running. |
False
You should NEVER attempt it! |
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What is the NSTM for Gas Free Engineering.
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NSTM chap 74 volume 3
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What is the inherent danger of gases produced by underwater cutting and welding.
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they are rich in oxygen and hydrogen and will explode if trapped and ignited
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What are two methods to remove trapped Gas if the gas mixtures are uncertain
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1. drill holes suitable locations to allow gas to escape
2.purge compartment with a mixture of gasses that will not support combustion |
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Oxygen cutting is about ___%
efficient |
60%
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Where does gas from underwater cutting usually collect
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closed compartments, open tubular structural members,open piping systems, under H beams and shaped structural members
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If you hear a pop during cutting and welding operations what should be done.
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if a pop is heard iti is a sign of underwater explosive gases collecting above the underwater work area, cutting or welding operations must stop and the cause must be investigated
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Why should care should taken when cutting or welding on enclosures that are on or above river beds especially in mud .
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because trapped methane gas in proper concentrations can explode
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Explosive gases may be produced by any one or a combination of what
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1.Petroleum products
2.Paint mixing mediums 3.Epoxies,adhesives and solvents 4.Ammunition/Explosives 5.Decaying vegetables or animal matter 6.Unburned gases from cutting torches |
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What are some methods to minimize the possibility of of explosions from trapped gases.
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1.start cutting from highest point and work downward
2.withdraw electrode every few seconds to allow water to enter the cut to not allow high temps to build up 3.Vent tube to the surface 4.venting from an internal valve inside the ship(if possible) |
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Why is AC power not used for underwater cutting/welding
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extreme danger involved with AC current,electric shock produced prevents voluntary relaxation of the muscles of the hand, i.e. the diver may not be able to let go if he enters the electrical circuit.
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All diver engaged in underwater cutting and welding operations should be thoroughly trained in what.
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CPR
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What following precautions must be observed at all times during cutting and welding operations.
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1.examinations must be made to learn how the cut away pieces will fall
2.Be extreamly careful when cutting wire rope 3.ensure ubilicals are not in the path of slag 4.avoid cutting overhead 5.never put down an electrode when the power is on 6.never change an electrode when the power is on 7.never allow body parts to come into contact with the equipment when the power is on 8.care must be taken when carrying large loose mettalic items (tools) ensure no contact with electrode or work |
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Do not lower the welding or cutting torch until.
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The ground clamp is securely attached near the work area
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All parts of the cable that are intended to be submerged shall be what
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fully insulated and watertight
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When working in deep waters what shall be done to the cables
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attach a strain relief
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The position of the ground in relation to the diver shall be what.
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positioned so that at no time the diver/equipment will come between the ground and the electrode
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What is a good rule of thumb to remember when cutting/welding underwater
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never turn your back to the ground when the power is on
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When AC power is used for u/w lighting or tools it must have what.
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Ground fault detection (GFD) or ground fault interuption (GFI) devices
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What is the most important piece of equipment in the underwater cutting and welding inventory
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The knife switch
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What are the things you must do to ensure proper funtioning of the knife switch
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the swich must be positively acting,ridgidly mounted and located so that it cannot be accidently knocked or vibrated closed
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What are the major causes of explosions
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1.combustables reached by the arc
2.flying sparks 3.hot slag 4.misuse of compressed gas cylinders 5.short circuits |
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True or False
you should never buff,steel wire brush or grind tools containing beryllium |
true,
it is toxic and can be harmful if particles are ingested |
