Ship ladders

What it is

A ship ladder – called a ship stair in OSHA terminology and a step-type ladder or stepladder in Australian and European standards – is a steep stair with treads rather than rungs, climbed facing the treads and with handrails on both sides. It occupies far less floor space than a conventional steel stair and is much safer to use than a vertical fixed ladder, especially where operators carry tools or climb several times a day.

Typical locations are mezzanine plant rooms, roof hatches, crane walkways, conveyor galleries, tank tops and equipment platforms. All three markets treat the ship ladder as an alternative used where a conventional stair is not practicable, so the space constraint should be documented in the design.

Types and options

Handrails are normally fitted on both sides and continue to the top landing so the user can hold on while stepping off. At the top, the platform guardrail has a self-closing gate or offset entry.

Design and compliance

United States. OSHA 29 CFR 1910.25(e) defines ship stairs with an angle of 60°–70° from horizontal, risers of 6.5–12 in (165–305 mm), a tread depth of at least 4 in (100 mm) and a tread width of at least 18 in (455 mm). Like all stairs under 1910.25, the ship ladder must carry five times the anticipated live load and never less than a 1,000 lb (4.45 kN) concentrated load. Handrails follow 1910.29(f): withstand 200 lbf (890 N) with at least 2.25 in (57 mm) clearance to any obstruction.

Australia. AS 1657-2018 covers step-type ladders, including the angle range, tread dimensions, handrails and landings; steeper than a stair and flatter than a rung ladder. Geometry is detailed per AS 1657, and the steel is designed to AS 4100 and fabricated to AS/NZS 5131. See Australian standards.

Europe. EN ISO 14122-3 covers stepladders as well as stairs and guard-rails, and EN ISO 14122-1 sets the order of preference for means of access – a stair before a stepladder, and a stepladder before a fixed ladder. Steelwork is designed to EN 1993-1-1 and executed to EN 1090-2. See European standards.

Ship ladders do not meet egress-stair rules for occupied buildings. They are for maintenance and operator access only.

Fabrication and finishing at World Steel

Stringers are CNC cut and drilled so tread pitch is exact, and treads are bolted or welded to AWS D1.1, AS/NZS 1554.1 or EN ISO 3834-2 procedures. Ship ladders are usually shipped fully assembled when they fit a container; longer units are split at a bolted joint. Handrails are fabricated with the ladder and test-fitted where specified.

The standard finish is hot-dip galvanizing by qualified galvanizers to ASTM A123, AS/NZS 4680 or EN ISO 1461; painted or duplex finishes are available to EN ISO 12944 or AS/NZS 2312.1. Treads use serrated grating or raised-pattern floor plate for slip resistance.

Installation and specifying

• Fix the top to the platform beam with the designed cleats; set the base on a level support and anchor it.
• Check that the tread surfaces are level after installation and that handrails are continuous to the landing.
• Specify the floor-to-floor height, available plan length and width, governing code, tread type and finish.
• Indicate any roof hatch, gate or adjacent obstruction that affects the top exit.

World Steel can supply ship ladders together with the platforms, guardrails and grating they serve.