FRP for Offshore and Marine: GRP Grating, Handrail and Ladders

In short: For offshore decks, specify each item separately. Grating: ASTM F3059 sets tests for FRP gratings used as an equivalent to steel gratings rated up to 94 lbf/ft² (4.5 kN/m²), and USCG Policy Letter 01-18 accepts listed gratings meeting it on US-inspected vessels. Handrail: as a US reference, OSHA sets a top rail of 42 in ± 3 in and a 200 lb test force. Fixed ladders: OSHA rung spacing is 10 to 14 in, and new ladders over 24 ft need a ladder safety or personal fall arrest system, not just a cage. FIBROVX builds each item to order.

How this guide fits with our others

This guide is a product specification guide for deck items. The marine corrosion zones are explained below, with a zone-by-zone checklist. Other sectors are on our industries page.

Rules first: whose rules apply

Offshore projects follow the rules of the flag state, class society, coastal authority and operator. Confirm them before you size anything. The OSHA dimensions below are US general industry rules and are given only as a reference point. Your project may set different values.

GRP grating

What ASTM F3059 covers

ASTM F3059-18 sets testing and performance requirements for FRP gratings used in marine construction and shipbuilding, as an equivalent to steel gratings rated for a maximum load of 94 lbf/ft² (4.5 kN/m²). Its scope notes that:

• It covers personnel safety, not support of equipment during or after a fire.
• Fire conditions are based on ASTM E119 exposure. It does not address hydrocarbon pool or jet fires.
• It is not a regulation or class rule.

What USCG Policy Letter 01-18 says

USCG Policy Letter 01-18 replaced the older PFM 2-98 guidance. It accepts FRP gratings meeting ASTM F3059 as equivalent to steel gratings on US-inspected vessels, including mobile offshore drilling units and floating production platforms. Gratings listed and labeled by an independent laboratory acceptable to the USCG do not need separate USCG type approval.

What to specify

• Location and fire level required by the project.
• Load, span and allowed deflection.
• Molded or pultruded, panel size, bar depth and mesh.
• Grit surface for wet decks.
• Clips and fasteners in stainless steel or FRP. See FRP molded grating and FRP grating fire ratings and ASTM E84.

GRP handrail

OSHA reference dimensions (29 CFR 1910.29)

• Top rail height: 42 in (107 cm), plus or minus 3 in, above the walking surface.
• Top rail strength: withstand at least 200 lb (890 N) applied downward or outward within 2 in of the top edge. Midrails, toeboards and gates follow the same section and your project rules.

What to specify

• Layout drawing with posts, corners and gates.
• Mounting: top or side mount, and the deck it fixes to.
• Toeboards where tools could fall.
• UV-stable color and surface for sun exposure. See FRP handrail systems and our FRP handrail systems guide.

GRP fixed ladders

OSHA reference rules (29 CFR 1910.23 and 1910.28)

• Rungs spaced not less than 10 in and not more than 14 in apart, center to center.
• Minimum clear width of 16 in between side rails on fixed ladders.
• Fixed ladders more than 24 ft (7.3 m) above a lower level: new ladders installed on or after November 19, 2018 need a personal fall arrest system or ladder safety system.
• By November 18, 2036, all such fixed ladders must have one of those systems. A cage alone will no longer meet the rule.

What to specify

• Height, landings and exit details.
• Ladder safety system type, if fitted.
• Rung surface for wet use.
• Brackets and stand-off from the structure. See FRP ladders and our FRP ladders and cage ladders guide.

Supports and frames

Frames, stair stringers and brackets can be built from FRP pultruded profiles. Isolate any steel you connect to and use compatible fasteners.

The three corrosion zones

The ABS guidance notes on cathodic protection of offshore structures, and NACE RP0176 before them, divide the outside of a steel offshore structure into zones:

• Atmospheric zone. Extends upward from the splash zone. Exposed to sun, wind, spray and rain. Corrosion is usually controlled with protective coatings.
• Splash zone. Intermittently wetted by waves, wind-blown spray and tides. ABS gives about 2 m (6 ft) in the Gulf of Mexico, about 9 m (30 ft) in Cook Inlet, Alaska, and up to 10 m (33 ft) in the North Sea during winter storms.
• Submerged zone. Below the splash zone, including anything below the mudline. Corrosion is controlled with cathodic protection, alone or with coatings.

A zone-by-zone checklist

1. Map the zones on your structure, using the local splash zone height.
2. List the items in each zone: grating, handrail, ladders, supports, trays.
3. Mark fire areas and the fire standard the project requires.
4. Set loads and spans for each item.
5. Choose resin and surface for UV and salt spray.
6. Choose hardware to avoid galvanic couples.
7. Confirm approvals needed by flag, class or operator.

Quotation checklist

1. Applicable rules: flag, class, operator.
2. Drawings with dimensions and zones.
3. Loads, spans and deflection limits.
4. Fire level required by area.
5. Surface, color and UV needs.
6. Hardware material.
7. Tests and documents you need.

How we customize

FIBROVX builds grating, handrail, ladders and profiles to your drawings. We do not claim ASME RTP-1 or any certification, including ASTM F3059 listing, USCG acceptance or class approval. Tests and documents for the items you order are agreed with each quotation.

Key parameters at a glance

Watch: FRP for Offshore and Marine in 27 Seconds

FAQ

Is GRP grating accepted on US offshore units?

On US-inspected vessels and units, USCG Policy Letter 01-18 accepts FRP gratings meeting ASTM F3059 when listed and labeled by an acceptable independent lab.

What load does ASTM F3059 cover?

It treats FRP gratings as an equivalent to steel gratings rated for a maximum load of 94 lbf/ft² (4.5 kN/m²).

How high should a handrail be?

OSHA general industry rules set the top rail at 42 in plus or minus 3 in. Your project rules may differ.

Can I still use a cage on a tall fixed ladder?

Not on new US ladders over 24 ft installed since November 19, 2018. Those need a ladder safety or personal fall arrest system.

Are your products certified for offshore use?

No listing or approval is claimed. Tests and documents are agreed with each quotation.

Related: Offshore Wind Transition Piece: GRP Grating, Handrail and Ladders; FRP in Offshore Wind Farms: A Map from Turbine to Substation; Phenolic FRP Grating: Low Smoke for Tunnels and Offshore.

Sources

• ASTM F3059-18, FRP Gratings Used in Marine Construction and Shipbuilding (scope, 94 lbf/ft² equivalency, E119 fire, not pool or jet fire, not a regulation): https://store.astm.org/f3059-18.html
• SAFETY4SEA, USCG Policy Letter 01-18 on FRP gratings (accepts F3059 gratings; replaces PFM 2-98; MODUs and floating production platforms; listed and labeled): https://safety4sea.com/uscg-publishes-guidance-on-fiber-reinforced-plastic-gratings/
• OSHA 29 CFR 1910.29, Fall protection systems criteria (top rail 42 in ± 3 in; 200 lb test force): https://www.law.cornell.edu/cfr/text/29/1910.29
• OSHA 29 CFR 1910.23, Ladders (rung spacing 10–14 in; 16 in clear width): https://www.law.cornell.edu/cfr/text/29/1910.23
• OSHA 29 CFR 1910.28, Duty to have fall protection (fixed ladders over 24 ft; 2018 and 2036 dates): https://www.law.cornell.edu/cfr/text/29/1910.28
• ABS, Guidance Notes on Cathodic Protection of Offshore Structures (Dec 2018) (atmospheric, splash, submerged zones; splash zone heights; CP limits in spray areas): https://ww2.eagle.org/content/dam/eagle/rules-and-guides/current/offshore/306-cathodicprotection-offshore-structures/cathodic-protection-offshore-gn-dec18.pdf
• NACE RP0176-2003, Corrosion Control of Steel Fixed Offshore Structures Associated with Petroleum Production (sections 3.2–3.3: splash zone design, GRP for handrails, conduit, stair treads, deck plates; galvanic caution): https://icdn.tradew.com/file/201801/1572618/pdf/6800350.pdf