A tower that fits perfectly in the shop can still stop a site crew for a week. Nine times out of ten the problem is not the steel. It is a bundle that arrived with the wrong section inside, a bolt list that does not match the packing list, or a member mark painted where the sling rubs it off during unloading.
Erection starts at the factory. These are the things we control before the container leaves, and the ones worth writing into a supply contract.
Every member carries a mark that ties it to one tower, one section and one position: something like T14-S3-M07 for tower 14, section 3, member 7. The mark is stamped or painted in a place that stays visible after bundling, and it appears on the packing list, the bolt list and the erection drawing with the same code.
Two mistakes show up repeatedly. Painted marks get rubbed off in transit, so stamping or a durable tag is safer on exposed faces. And when a mark is applied by hand at the end of a shift, the last digit goes wrong. We check marks against the drawing at the packing station, not at the end of the line, because that is where the error is still cheap to fix.
Bolts are the most common cause of a stalled site. A tower can need several thousand, in three or four diameters and two or three grades, and the crew cannot substitute one for another. Our rule is simple: each bundle carries its own bolt box, labelled with the tower and section, containing the sizes that bundle needs plus a small surplus.
| Item | What the site needs | What goes wrong |
|---|---|---|
| Bolts and nuts | Counted per bundle, bagged and labelled | One size short, whole section waits |
| Washers | Taper washers for leg slopes | Improved by guesswork, joint loosens |
| Bolt grade | 4.6, 6.8 or 8.8 to ISO 898-1 | Mixed grades in one box |
| Spare parts | About 1 percent of total count | Dropped bolts stop work |
A bundle that is too heavy for the site crane is a problem created in the yard. We keep bundles to roughly 1.5 to 2.5 tonnes and mark the centre of gravity, so a 25 tonne crane can lift sections without a second machine. Long leg angles are bundled with lifting slings already positioned, because a sling that cuts into a galvanized edge leaves a repair nobody wants to make at height.
A 40 ft high cube takes about 24 to 26 tonnes of tower steel. On lattice towers the volume limit usually arrives first: sections are bulky, and if they are not nested properly, the container sails half empty and the freight cost per tonne doubles.
Foundations set the geometry. Anchor bolt templates have to match the tower base before the concrete cures, and a 5 mm error at the base becomes a visible lean 60 m up. After erection, GB 50233 allows a tower inclination of up to 3 mm per metre of height; telecom specifications often ask for 1 mm per metre. The number belongs in the contract, because it decides how much shimming the crew does at the base plates.
What the crew should not do is weld. Tower members are bolted. Field welding burns the galvanizing, changes the steel at the heat-affected zone, and cannot be inspected to shop standard. If a member does not fit, the right move is to stop, photograph the joint with the mark visible, and send it to the factory. The part is usually in the next shipment, and the fix is a phone call instead of a repair procedure.
Damaged galvanizing on a few square centimetres is different. That is repaired with zinc-rich paint in two coats to reach the specified thickness, following the repair clause in ISO 1461. Anything larger, or any damage on a structural weld, needs the part replaced.
About 24 to 26 tonnes of fabricated tower steel in a 40 ft high cube, and on bulky lattice sections the volume runs out before the weight does. Long leg angles and crossarms are usually nested to use the full 12 m length. Packing density is a design decision, not an afterthought, because it sets the freight cost per tonne.
A packing list organised by tower number and section, a bolt list per bundle, erection drawings, mill certificates to EN 10204 3.1, coating thickness reports, and any trial assembly or inspection report the contract requires. The packing list is the one the site crew uses first, so it has to match the physical marks on the bundles exactly.
Chinese acceptance rules for overhead lines, GB 50233, allow a tower inclination of up to 3 mm per metre of height measured after erection. Many telecom specifications are tighter, often 1 mm per metre. The tolerance should be stated in the contract, because it decides how much shimming the site team has to do at the foundation interface.
No. Tower members are bolted for a reason: field welding burns off the galvanizing, changes the metallurgy of the member and cannot be inspected to the same standard as shop work. If a part does not fit, the site should stop, photograph the joint and contact the factory. Almost every fit problem traces back to a missing match mark or a packing error, and both are solved by sending the right part.
Send the tower list and the delivery window. We will confirm the packing plan, container count and document pack.
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