Manitowoc Published 10-01-2012, Control # 045-08 4-17
777 SERVICE MANUAL BOOM
4
REPAIR PROCEDURE
Extent of Repair
Field repair is limited to replacing damaged lacings —
unless otherwise approved by Manitowoc — but only if
the following conditions are complied with:
• The lacings are ordered from Manitowoc.
• The welding is done by competent welders qualified to
work with the types of steel involved. Manitowoc
recommends that welders be qualified per Section 5 of
AWS D1.1 Structural Steel code or an equivalent code.
• The welding procedures and specifications supplied by
Manitowoc are adhered to.
Preparing for Welding
Many of Manitowoc’s current production cranes are
equipped with sensitive electronic equipment and controls.
To prevent serious damage to these components, take the
following precautions before you start welding:
1. Obtain factory approval before performing any welding.
2. Stop the engine, disconnect all positive (+) and negative
(-) battery cables from the batteries or use the battery
disconnect, if equipped.
3. Do not attach welding cables to or near any electrical
components. If welding is required near any electrical
components, the component should be removed from
the unit prior to welding and reinstalled after welding is
completed.
4. Attach the welding ground cable as near as possible to
the area being welded. Do not lay the welding ground on
the lattice section — secure it tightly with a C-clamp if
necessary.
5. Do not bridge electrical components and machined
bearing surfaces.
6. Cover electrical components and machined surfaces as
required prior to welding to protect them from welding
sparks and spalls.
Repair Facility
To ensure proper welding, the repair area must:
1. Be heated to 70° F (21° C) minimum.
2. Be free of wind drafts.
3. Be rain and snow proof.
4. Have proper ventilation.
5. Have proper lighting and electrical service.
6. Have proper air compressor capacity to support air arc
gouging and grinding equipment.
7. Have sufficient room to pin another lattice section to the
work piece if necessary.
Outdoor Repairs
Welding shall not be done when the outside temperature is
lower than 45° F (7° C) or when surfaces are wet or exposed
to rain, snow, or high wind velocities.
Welding is permitted if a heated structure or shelter is
constructed around the weld area to maintain the
temperature adjacent to the weldment at 45° (7°C) or higher.
REGARDLESS OF OUTSIDE TEMPERATURE, THE BASE
MATERIAL TEMPERATURE MUST BE MAINTAINED AT
THE MINIMUM INTERPASS TEMPERATURE DURING ALL
WELDING OPERATIONS.
General Equipment Requirements
The following equipment is required:
1. 350+ amp DC power source (needed for carbon arc
gouging and welding).
2. Stick electrode (see page page 4-27 for determining
required amount).
3. Carbon arc torch.
4. Stick electrode oven and proper storage for electrodes.
NOTE Stick electrode can be purchased in hermetically
sealed packages from Manitowoc Crane Care.
• Electrode: A.W.S. A5.5
• 3/32 in (2,5 mm) E9018M-H4
• 1/8 in (3,2 mm) E9018M-H4
The maximum exposure time to the atmosphere for
E9018-M stick electrode is one hour. The electrode
must then be returned to an oven that is held at a
minimum of 250°F (121°C) for four hours.
5. Safe and properly sized rigging for lifting and blocking
equipment.
WARNING
Component Failure!
Unless otherwise approved by Manitowoc, no welding
shall be done to chord members or platework except to
attach lacings.
No chord member or platework may be replaced in whole
or in part. The complete lattice section must be replaced if
damage to chords or platework exceeds the allowable
criteria contained in this publication.
Welding chord members or platework without approval
from Manitowoc could result in structural failure of the
attachment.
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