Lattice boom sections · Chords, lacings and lugs; dent, bend, corrosion and straightness limits; repair or scrap; pins and blocking during assembly
A lattice boom is a truss: main chords held apart by lacings, built in pinned sections — a butt or base section at the crane, inserts in between and a tip carrying the sheaves. Its strength depends on every chord staying straight and every lacing staying attached, so a lacing bent in transport or a dent from a dropped load matters more than its size suggests. Boom sections are bought with a crane, as spares, or as extra inserts for more length, and each section has to be inspected before it goes back into the air.
The lattice boom and its sections — base, inserts and tip — on crawler, deck and offshore cranes: chord and lacing construction, section identification, field inspection limits for dents, bends, corrosion and chord straightness, repair or replacement, and the blocking and pin-removal rules for assembly and disassembly. Complete lattice-boom crawler cranes are covered on the Crawler crane page and pedestal-mounted offshore cranes on the Offshore crane page.
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01
Manitowoc's lattice section bulletin F1316 tells owners not to operate a crane with damaged lattice sections and to have a qualified person inspect them weekly, before first use, after transport and after an overload or shock load. [1] Link-Belt's boom inspection manual sorts findings into conditions to repair, cosmetic conditions, and conditions that require the section to be destroyed. [2]
Manitowoc measures chord straightness by blocking both ends of the removed section, stretching a line tight along the chord and measuring to it in the horizontal plane, then rolling the section 90° and measuring again. [1]
Editorial calculation: Link-Belt's no-repair curvature of 1/32 in per foot on a lacing 3 ft long allows 3 × 1/32 = 3/32 in (about 2.4 mm); its straightening limit of 1 in across 36 in on the same lacing is 1 in (25 mm). The lacing length is assumed. [2]
| Condition | Manitowoc F1316 | Link-Belt 632K |
|---|---|---|
| Dents | Tubular: not deeper than wall thickness or 1/8 in (3.2 mm), whichever is less; angles and platework: 1/8 in [1] | Unacceptable dents in chords: section destroyed; limits in its Appendix A [2] |
| Bent lacing | Gradual bends up to 5 % of tube diameter or angle leg length; may be cold-straightened [1] | No repair up to 1/32 in per ft (1 mm per 40 cm); straighten up to 1 in across 36 in; replace beyond [2] |
| Chord straightness | Within ±3/16 in (4.8 mm) at each lacing intersection; angle toe waviness ±1/4 in (6.4 mm) [1] | Within 3/16 in (4.8 mm) per free span or 1/4 in (6.4 mm) over the section [2] |
| Corrosion | Not deeper than 10 % of wall, angle or plate thickness [1] | Unacceptable pitting or corrosion on chords: section destroyed [2] |
| Kinks and cracks | Kinked or cracked lacings replaced; chords referred to the maker [1] | Any crack in a main chord or lug: section destroyed [2] |
Record the crane serial number, boom identification number and section part number with every finding; both makers ask for them before supplying repair data or replacement lacings.
02
Link-Belt also requires a section to be destroyed if a chord has prior repairs other than authorised lattice replacement, if non-original brackets, rigging parts or walkways have been welded to a chord, or if a crack runs from a weld into the chord, and it asks that only Link-Belt approved materials be used. [2]
Manitowoc allows gradual bends in lacings and chords to be cold-bent back into alignment but forbids straightening kinks, and refers any kinked or cracked chord or platework to Manitowoc Crane Care for approved repair instructions. It gives lacing and chord wall thicknesses in the lacing drawings of each crane's parts manual, for example 0.188 in (4.8 mm) for the two top chords of one boom top. [1]
03
OSHA's crane rule for construction, 29 CFR 1926.1404, requires blocking under lattice booms or components to be placed so that it protects the structural integrity of the equipment and prevents dangerous movement and collapse. Manufacturer limits on the length of boom supported only by cantilevering must not be exceeded, and where none exist a registered professional engineer must set the limit in writing. While pins or similar devices are being removed, employees must not be under the boom, jib or other components unless the rule's exception is met. [3]
The same section requires the weight of each component to be readily available, which for a boom means the weight of each insert and the tip as they will be lifted. [3]
04
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Crane: [make; model; serial number] Boom: [identification number; type: angle or tubular] Section: [base / insert length / tip; part number] Damage found: [location; measurements] Certification: [class or API 2C if offshore]
2 companies list this product among what they make. Company figures are quoted from each company's own website; every card states where the relationship came from.
Lists lattice boom deck cranes and lattice boom platform cranes; the boom is supplied as part of the crane.
Product scope checked 2026-10-17
Lists an API 2C lattice boom offshore platform crane range of 50 to 300 t SWL with outreach up to 50 m.
Product scope checked 2026-10-17
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Manitowoc allows no more than the wall thickness or 1/8 in (3.2 mm) on tubular members, whichever is less. [1]
Both makers allow gradual bends to be straightened within limits; kinks and cracks mean replacement. [1] [2]
Link-Belt scraps sections with any crack in a main chord or lug, chord straightness outside 3/16 in per span, or unauthorised repairs or welded attachments on a chord. [2]
Sources checked 2026-10-17. The damage limits are quoted from the boom maintenance publications of two crane builders, Manitowoc (F1316) and Link-Belt (book 632K). The assembly rules are US federal regulation, read from the eCFR.
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