Cargo: List 8 precautions when using a union purchase rig

Question

List 8 precautions when using a union purchase rig

Sophie March · Accepted Answer

a)The minimum operating angle of either derrick should be not less than 15° to the horizontal
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.

Sophie March · Answer

i) Derricks should be topped as high as practicable, and not rigged farther apart than is absolutely necessary.

Sophie March · Answer

j) Derricks should be marked with the safe working load when rigged for union purchase.

Sophie March · Answer

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.

Cargo

List 8 precautions when using a union purchase rig

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