| Typical density |
0.93–0.97 g/cm³ |
Approximately 7.9–8.1 g/cm³ |
Approximately 1.5–2.0 g/cm³, depending on fiber and resin content |
HDPE and FRP are much lighter than stainless steel, which can simplify handling and installation. |
| Typical tensile strength |
Approximately 20–37 MPa for common outdoor grades |
Approximately 515 MPa minimum for annealed 304; approximately 485 MPa minimum for annealed 316 under common product specifications |
Often approximately 100–300 MPa in the fiber direction; highly dependent on laminate design and fiber orientation |
The finished slide geometry, wall thickness, supports, and safety testing are more important than material strength alone. |
| UV resistance without stabilizers |
Limited; prolonged sunlight can cause chalking, embrittlement, and color fading. |
Very high; sunlight does not normally degrade the metal matrix. |
Moderate to high; the resin surface may chalk, fade, or lose gloss under prolonged UV exposure. |
Do not judge UV performance from color alone; request the resin or polymer formulation and test method. |
| UV protection commonly specified |
UV-stabilized grade, often with carbon black or approved light stabilizers. Carbon-black content of approximately 2–3% is widely used for UV-stabilized polyethylene compounds, subject to the applicable material specification. |
No polymer UV stabilizer required; surface finish and cleanability remain important. |
UV-resistant resin, surface veil, and a suitable gel coat or topcoat are commonly used. |
For international projects, specify UV exposure testing such as ISO 4892-3, ISO 4892-2, or ASTM G154/G155 rather than using an unverified “UV-proof” claim. |
| Useful UV test indicators |
Report color change, surface cracking, tensile retention, and elongation retention after a defined exposure cycle. |
Report surface discoloration, tea staining, pitting, and corrosion after exposure; UV-only testing is generally not the controlling durability test. |
Report gloss or color change, chalking, blistering, cracking, and laminate strength retention after exposure. |
A meaningful result must include irradiance, black-panel temperature, humidity, exposure duration, and acceptance criteria. |
| General corrosion resistance |
Excellent against water, salts, and many diluted acids and alkalis; can be attacked by strong oxidizing agents and some hydrocarbons. |
304: good in ordinary outdoor environments; 316: improved resistance in marine or chloride-rich environments due to molybdenum content. |
Very good when the resin system is correctly selected; chemical resistance varies substantially with resin, laminate, joints, and surface protection. |
For coastal sites, chloride exposure, drainage, fasteners, joints, and hidden supports must be evaluated together. |
| Salt-spray or marine suitability |
Excellent material resistance; inspect for UV aging and mechanical damage. |
304 may develop tea staining or pitting in coastal chloride conditions; 316 is generally the safer choice, but it is not immune to corrosion. |
Generally excellent; protect cut edges, drilled holes, joints, and exposed fibers from water ingress. |
Use marine-grade design details and compatible fasteners; material selection alone does not prevent galvanic or crevice corrosion. |
| Relevant corrosion test references |
Chemical immersion or exposure testing should be selected for the expected cleaning agents and site chemicals. |
ASTM B117 or ISO 9227 may be used for salt-spray comparison, but salt-spray hours should not be treated as a direct prediction of field life. |
Chemical-resistance testing should reflect the resin system and expected exposure; exposed fiber and edge-sealing performance should also be checked. |
Always request the exact test conditions, specimen preparation, rating system, and post-test inspection criteria. |
| Thermal expansion |
High, typically around 100–200 × 10−6/°C depending on grade and orientation |
Low to moderate, approximately 16–17 × 10−6/°C for common austenitic grades |
Variable, often approximately 10–30 × 10−6/°C along the fiber direction and higher transverse to it |
HDPE requires allowance for movement, slotted holes, and appropriate fastening details in hot and cold climates. |
| Surface temperature in direct sun |
Lower thermal conductivity than metal, but dark colors can still become hot. |
High thermal conductivity; exposed surfaces can become hot quickly in direct sunlight. |
Lower thermal conductivity than stainless steel; dark gel coats may heat significantly. |
Color, shade, ventilation, touch-point design, and burn-risk assessment should be included in the specification. |
| Maintenance profile |
Low; clean with compatible detergents and inspect for deep scratches, warping, and UV embrittlement. |
Low to moderate; regular cleaning reduces staining and chloride-related surface corrosion. |
Low to moderate; inspect gel coat, cracks, blisters, exposed fibers, and edge seals. |
A documented inspection and cleaning schedule is more reliable than a material-only maintenance claim. |
| Typical best-fit environment |
General outdoor parks, hot climates, humid areas, and locations requiring lightweight components. |
High-wear public installations where rigidity, premium appearance, and fire or hygiene considerations are important; 316 is preferable for many marine sites. |
Large molded forms, corrosive environments, and projects needing a balance of low weight and structural stiffness. |
The best material depends on climate, vandalism risk, user capacity, required shape, budget, and local safety regulations. |
| Recommended procurement evidence |
Material grade, UV stabilizer specification, thickness, UV test report, color-retention data, and dimensional inspection. |
Steel grade certificate, surface-finish specification, weld-quality records, corrosion test details, and fastener compatibility statement. |
Resin and glass-fiber specification, laminate schedule, UV topcoat details, edge-sealing procedure, and chemical-resistance data. |
Require product-level test documentation and compliance with the playground standard applicable to the destination market. |