Site preparation, foundations, ballast, guys and anchorages
Ground and foundation
Derrick cranes transfer enormous loads into the ground through the mast foot, the anchor points and, for stiff-leg types, the leg footings. The ground must be assessed for bearing capacity, and footings designed for the actual loads - including uplift on anchors. Traps: assuming compacted fill is adequate without testing; placing anchors in ground that can be softened by rain or excavation nearby; and ignoring adjacent excavations that reduce the soil wedge holding an anchor.
Ballast and anchorage
Where ballast or counterweight is specified, it must match the manufacturer's or engineer's requirement exactly - no substitutions, no "close enough" concrete blocks. Anchors must be set at the designed angle so the guy pulls in line with the anchor's capacity; a guy pulling at a different angle can pull the anchor out. Turnbuckles must be adjusted evenly so tension is shared, and locknuts or locking devices fitted.
Guys
Guy ropes must be free of kinks, broken wires, corrosion and heat damage; they must not rub on structures or pass through sharp edges. Keep guy lines clear of traffic and mark them so mobile plant does not strike them.
Worked example
If an anchor is designed for a guy at 45° and the guy is re-set at 30°, the horizontal component rises and the anchor may fail in pull-out. The rule: never change guy angles without engineering approval.
Handover
Record anchor positions, tensions and footing details so the next erection matches the design.