Cargo Handling Equipment Flashcards
What are the advantages of using a crane instead of a derrick?
*Simple operation;
* Single-man operation, derricks are more labour intensive;
* Clear deck operational views;
* Clear deck space of rigging;
* Versatility with heavy loads, and not required to de-rig;
* 360° slew and working arc when compared with limited operating areas for derricks;
* Able to plumb any point quickly making a faster load/discharge operation;
* Enclosed cabin for operator, where as the majority of derrick operators are exposed, offering
greater operator protection and comfort;
What are the disadvantages of using a crane instead of a derrick?
- Comparatively high installation cost
- Design is more complex, leaving more to go wrong.
- Specialist maintenance required, hydraulics and electrics.
- The SWL of cranes is generally less than that of specialist derrick rigs
What information is contained on a rigging plan?
a) Position and size of deck eye plate
b) Position of inboard and outboard booms
c) Maximum headroom (i.e. permissible height of cargo block above hatch coaming)
d) Maximum angle between runners
e) Position, size and SWL of blocks
f) Length, size and SWL of runners, topping lifts, guys and preventers
g) SWL of shackles
h) Position of derricks producing maximum force
i) Optimum position for guys and preventers to resist such maximum forces
j) Combined load diagrams showing forces for a load of 1 tonne or the SWL
k) Guidance on the maintenance of the derrick rig
Discuss the maintenance schedule for cargo handling equipment
All grease nipples on winches, blocks, derrick heels, crane ‘turntable’ and similar equipment
should be attended to weekly.
2. Inspection of ancillary equipment such as chains, rings, hooks, swivels, blocks, and shackles every 3 months.
3. A thorough overall of the above equipment every 6 months. The derricks or derrick cranes should be stripped of all the ancillary equipment and the gear taken apart, examined, greased, and re-assembled.
What precautions should be taken when working with a Union Purchase Rig?
a) The minimum operating angle of either derrick should be not less than 15° to the horizontal, and
it is recommended that the angle be not less than 30°;
b) The maximum included angle between the cargo runners must not exceed 120°;
c) The outreach beyond the midship breath of the ship should not be less than 4m.
d) Unduly long slings should not be used by stevedores;
e) The standing guy must be of adequate strength, the deck eye plate where it is secured must be
in an appropriate location;
f) Rigging of derricks to be supervised by a competent person;
g) Runners should not be permitted to rub against hatch coaming or other structures, fast wear will happen;
h) Maximum load must not exceed either 1/3 the SWL of the lowest rated derrick in the pair or
absolute maximum of 2.5 tonnes.
i) Derricks should be topped as high as practicable, and not rigged farther apart than is absolutely
necessary.
j) Derricks should be marked with the safe working load when rigged for union purchase.
k) Preventer guys of adequate strength should be rigged on the outboard side of each derrick, and
secured to the deck in the same line and with similar tension as the slewing guy. However, they must be secured to separate pad eyes to the eyes which accommodate the slewing guys.
What are the disadvantages of the Union Purchase?
- Can be used only for light loads (1.5 to 2 tons)
- The winchman must be highly skilled and experienced
- The derricks cannot be used for “spot loading”
- Repositioning the derricks is time consuming
Describe how you would change a rig from a single runner to a gun tackle (doubling up), with
and without a spiderband.
Should the derrick not have the convenient second spider band, then it will be necessary to parcel the derrick with canvas and take a half hitch with the runner around the derrick, taking the eye of the
runner and securing it to the lug on the spider band that accommodates the topping lift. This effectively produces a similar bight in the wire for the floating block as previously described.
