Factory-Direct Since 2004
Tri Arc
Fixed Ladders
Tri-arc style fixed ladders with safety cage — steel with hot-dip galvanized finish, standard heights 12–22 ft and up, cage built per OSHA 1910.27.
Cage Hoop Profile
Rung Load Rating
Rung Width
HDG Finish
Specifications
Tri Arc Fixed Ladder Specifications & Dimensions
Tri-arc ladders share the same ladder core as our full line, with the three-bend cage profile built around it. Standard heights 12–22 ft and up.
| Specification | Standard Range | Custom |
|---|---|---|
| Height | 12 – 22 ft and up | Up to 40 ft engineered |
| Standard Lengths | 10 / 12 / 14 / 16 / 18 / 20 / 25 / 29 ft | Any length |
| Cage Diameter | Φ700 mm (≈27.6″ ID) | Custom |
| Cage Start Height | 7 – 8 ft up the climb | Per project |
| Cage Hoop Spacing | ≤1,200 mm | Tighter on request |
| Rung Diameter | Φ20 mm (0.79″) | Per spec |
| Rung Spacing | 280 mm / 11″ (≤300 mm) | Per project spec |
| Clear Width | 500 mm (19.7″) | Custom width |
| Load Rating | 1.5 kN per rung (≈337 lbf) | Engineered |
| HDG Thickness | 85 – 100 μm (ISO 1461) | Heavier coating |
| Material | Q235B steel, HDG finish | SS304 / SS316 / AL |
Tri-Arc Style
Tri Arc Fixed Ladder
"Tri-arc" describes the three-bend arc profile of the cage hoops. Instead of a plain flat ring, each hoop is formed with three shallow arcs, which stiffens the hoop against side load and gives the cage its distinctive look. It is the classic US industrial fixed-ladder cage, built to the same OSHA 1910.27 geometry.
- Steel construction, hot-dip galvanized finish
- Three-bend arc hoops for rigidity
- Cage per OSHA 1910.27 — same specs as the field standard
- Factory-direct pricing, no middleman markup
Safety Cage
Cage Built Per OSHA 1910.27
The cage is not an add-on afterthought — it is fabricated as part of the tri-arc ladder system.
Φ700 mm Cage
≈27.6 in internal diameter — room to climb with backpack and tools.
Hoop Spacing
Vertical hoop spacing ≤1,200 mm, vertical bars welded at the arc points.
Start Height
Cage starts 7–8 ft up the climb per the OSHA field convention.
HDG Finish
Hot-dip galvanized 85–100 μm per ISO 1461 for outdoor life.
Choose Your Configuration
Tri Arc Fixed Ladder Options & Configurations
Steel, HDG finish as standard — stainless and aluminum available. Custom & standard options.
Tri-Arc With Cage
The classic tri-arc caged ladder, hot-dip galvanized. Our most specified configuration for industrial outdoor access.
Tri-Arc Without Cage
The same ladder core without a cage, for low runs or PFAS-equipped climbs. Rungs, stiles and HDG finish unchanged.
SS & Aluminum Tri-Arc
SS304/SS316 for chemical and marine sites, 6063-T5 aluminum for light weight — same tri-arc cage geometry.
Certifications
Compliance & DoCumentation (OSHA/BS 4211/EN ISO 14122-4)
- OSHA 1910.27 — Cage per code
- BS 4211:2005+A1:2015
- EN ISO 14122-4
- AS 1657
- DoC, MTC 3.1, Structural Calcs with Every Order
Documentation Package
Every order ships with complete documentation — no extra cost, no paywall.
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Declaration of Conformity (DoC)
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Material Test Certificates — EN 10204 3.1
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Structural Calculations
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Welding Procedure Specifications
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Surface treatment certificates (HDG per ISO 1461)
Global Shipping & Factory
Built in China, Delivered Worldwide
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8–12 × 40ft containers shipped per month
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VCI rust protection + ISPM 15 heat-treated wooden crates
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EXW / FOB / CIF terms available
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15–25 business days production lead time
Factory-Direct Pricing
Factory-Direct Pricing & 24h Quote
Same specs as the field-standard tri-arc ladder, at factory-direct prices — every line item transparent.
Custom quotation priced by weight & process. Industry reference: caged tri-arc ladders ≈ USD 899–1,099/ton.
Common questions
10, 12, 14, 16, 18, 20, 25 and 29 ft as standard; any other length is engineered from your drawing with the free drawing review.
Yes — SS304/SS316 and 6063-T5 aluminum versions keep the same Φ700 mm hoop geometry and Φ20 mm rung core.
About 100 mm from rung end to cage ID — enough room to climb freely with no pinch points at any hoop height.
Hot-dip galvanized 85–100 μm per ISO 1461, with pickled or painted options and HDG coating reports with the order.
Yes — M12 U-bolt and standoff bracket loads are verified in the engineer-signed structural calcs that ship with every order.
Tri-Arc Build Detail
Tri Arc Fixed Ladder — Step Geometry & Pole-Mount Design
"Tri-arc" describes the cage: each hoop is formed from three arc segments — one top arc and two side arcs — pressed and welded into a single Φ700 mm ring. The ladder core and rungs stay identical to our full fixed ladder line, and a pole-mount version adapts the same build to round structures.
| Tri-Arc Step & Mount Specification | Standard Range | Custom / Note |
|---|---|---|
| Cage Hoop Build | 3-segment arc hoop, Φ700 mm ID | Top arc + two side arcs, welded per hoop |
| Cage Hoop Spacing | ≤ 1,200 mm | OSHA; tighter on request |
| Cage Vertical Bars | Spacing ≤ 240 mm (9.5 in) | Legacy OSHA 1910.27(c)(5) |
| Cage Start Height | 7 – 8 ft up the climb | Per project |
| Rung Diameter | Φ20 mm (0.79 in) | Same core as full line |
| Rung Spacing | 280 mm / 11 in (≤ 300 mm) | OSHA 1910.23(d) |
| Clear Width | 500 mm (19.7 in) | Custom width |
| Rung-End to Cage ID | ≈ 100 mm (no pinch point) | Φ700 cage / 500 mm ladder geometry |
| Pole-Mount Brackets | Fit Φ150 – 300 mm pole diameters | Clamps per section |
| Pole Standoff (pole face to rung) | 200 – 250 mm | Keeps toes clear of the pole face |
| Pole Fixing | M12 U-bolts or band clamps, 2 per section | HDG; per calc |
| Load Rating | 1.5 kN per rung (≈337 lbf) | Bracket loads in structural calcs |
Why Three Arcs
The tri-arc hoop build
- Formed, not field-bent: each hoop is pressed from three arc segments, so the Φ700 mm ID and roundness are consistent on every hoop.
- Stronger joints: three short welds per hoop beat long field bends — cleaner geometry, no flat spots to snag a glove.
- Uniform cage feel: the climber gets the same clearance at every hoop height — 100 mm from rung end to cage ID, no pinch points.
- Same ladder core: Φ20 mm rungs at 280 mm, 500 mm clear width, 1.5 kN per rung — identical to our standard line for easy spec'ing.
Pole-Mount Design
Climbing round structures — pole style
- Pole diameter fit: brackets are sized for Φ150 – 300 mm poles; tell us the measured diameter at top and bottom.
- Standoff geometry: the ladder sits 200 – 250 mm off the pole face so the climber's toes clear the round surface on every rung.
- Fixing: M12 HDG U-bolts or band clamps, two per section, torque specified; bracket capacity is in the calcs.
- Tapered poles: arc-shaped spacer plates take up the diameter change so the ladder stays plumb along its height.
- Typical use: water towers, silos, storage tanks, utility structures and tall round process vessels.
Tri Arc Fixed Ladder — Buyer FAQ
The cage hoop is formed from three arc segments — one top arc and two side arcs — welded into one Φ700 mm ring. It's stronger and rounder than long single-piece field bends.
Φ20 mm rungs at 280 mm (11 in) spacing, 500 mm clear width, 1.5 kN per rung — the same ladder core as our full fixed ladder line.
Yes — the pole-mount version uses M12 U-bolts or band clamps for Φ150 – 300 mm poles, with a 200 – 250 mm standoff so toes clear the round face.
Φ700 mm ID hoops at ≤ 1,200 mm spacing, vertical bars ≤ 240 mm (9.5 in) apart, cage starting 7 – 8 ft up the climb — per OSHA 1910.27 cage geometry.
12 – 22 ft standard and up; any length is engineered from your drawing, with the free drawing review confirming cage and anchor layout.
Proven in real facilities
Reference projects are shown by industry, country and scale. Client names are available on request with approval.
National utility projects — 15+ countries
23 documented projects, 2021-2025 · 2025
All standardsEnergy & industrial clients — Global
500+ projects since 2004 · 2004-2025
Full compliance docsLargest single order — Malaysia
60 units in one project · 2021
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Why Work With Dengtai?
Full Compliance Docs
DoC, MTC 3.1, structural calcs included free.
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Engineering review + itemized quote within one day.
Global Delivery
8–12 containers/month. VCI + ISPM 15 packaging.
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Related Tri Arc Fixed Ladder Pages
Explore cage, material, and standards resources for your project.
Cage Fixed Ladders
Safety cage configurations per OSHA 1910.27
Steel Fixed Ladders
Q235B structural steel, hot-dip galvanized
Stainless Steel Ladders
SS304 & SS316 for corrosive environments
OSHA 1910.27
Full OSHA compliance documentation
Fixed Ladder Standards
OSHA, BS 4211, EN ISO 14122-4 & AS 1657
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