Explore the world of FRP with us
Want to know more about our FRP – fibreglass products? In this section you will find answers to the most frequently asked questions about M.M. and our composite material solutions. From chemical resistance to installation methods, from certifications to specific applications: discover everything you need to know to choose the products best suited to your needs. And if you can’t find the answer you’re looking for, contact us. We will be happy to help.
What types of reinforcement does M.M. use?
Polyester resins are reinforced with glass fibres to increase their mechanical strength. Glass fibres are chosen for their mechanical strength, non-flammability, resistance to decay, good chemical resistance, dimensional stability, heat resistance and colourlessness.
The main types of glass fibre used by M.M. are Type “E”, for general applications and good electrical properties, and Type “ECR”, for enhanced performance. For grating production, M.M. uses Roving fibres (a bundle of several essentially parallel strands/filaments wound onto a spool) as well as Mat and woven fabrics for laminates and covered gratings. For profile production, both Roving fibres and continuous strand mat — made of continuous filaments arranged in random orientations and connected together in a spiral pattern — are used, along with woven fabrics. To achieve high-quality profiles, a surface polyester veil is also applied to prevent fibre bloom, thereby increasing the durability of the finished product.
What are the advantages of fibreglass/FRP?
Choosing FRP products as an alternative to more traditional materials such as galvanised or stainless steel, concrete and wood can bring decisive advantages depending on the field of application and the stakeholders involved.
By way of example, and without being exhaustive:
- the lightness of the material (on average 75% lighter than the equivalent steel product) makes it particularly useful for designers in all cases where the load on existing structures/foundations needs to be minimised, and also for installers, who can move materials on site without special lifting equipment;
- the high corrosion resistance, comparable to that of AISI 316 stainless steel, allows designers to offer end clients a solution that meets the requirements of aggressive environments at a more competitive price than stainless steel, and only slightly higher than galvanised steel;
- the electrical insulation makes it the preferred choice for designers and clients in any application where the risk of electrocution needs to be minimised, while also avoiding the need for an earthing system;
- the ease of on-site processing, even with unsophisticated equipment, makes this solution preferable for designers and installers in terms of time and cost, as it minimises the need for prior measurement surveys and detailed engineering.
How does FRP behave in the presence of fire?
Polyester resins are combustible. There are no non-flammable resins, but polyester resins can be formulated with limited flammability or self-extinguishing properties — meaning that, once cured, they stop burning once the ignition source is removed.
Self-extinguishing properties can be achieved through various methods. M.M. uses aluminium hydroxide as a flame retardant, which decomposes at around 180°C, absorbing a considerable amount of heat in the process and releasing water vapour. In addition to acting as a fire retardant, it is highly effective as a smoke suppressant. No halogens are used.
M.M.'s IFR gratings are classified as Bfl-s1 in accordance with EN 13501-1.
IFR gratings have also been assessed for the dripping parameter, which describes the release of molten droplets of the product or the production of burning particles during and after combustion, and are classified as level d0 — meaning no dripping.
Why choose an FRP grating over a metal grating?
FRP gratings offer a range of advantages over galvanised steel and stainless steel gratings:
- Corrosion resistance. FRP is extremely resistant to corrosion. This characteristic makes it an excellent choice for chemically aggressive environments. FRP gratings withstand a wide range of acidic and alkaline chemicals for long periods, across a good temperature range.
- FRP gratings are much lighter than steel gratings, reducing the load on underlying structures and making them easier to install. This is particularly important in all applications where weight is a critical factor.
- Electrical insulation. Unlike steel, FRP does not conduct electricity. This is a significant advantage in power generation plants, electrical stations and substations, railway lines, and production sites where high-voltage electric current is present. It ensures the safety of operators and users from the risk of electrocution and eliminates earthing costs.
- FRP gratings require less maintenance than steel gratings. They do not need repainting or treatment to prevent corrosion, including galvanic corrosion.
- Service life. Thanks to their corrosion resistance, FRP gratings tend to last longer than traditional steel gratings in many environments.
- Non-magnetic. Unlike steel, FRP is non-magnetic and can be used in environments where it is important to avoid interference.
Is FRP resistant to high and low temperatures?
FRP has excellent resistance to low temperatures and, unlike some metals and many plastics, becomes much stronger at very low temperatures thanks to the positive effect of the reinforcement.
As for high temperatures, the properties of FRP decrease as the temperature rises, but show a less pronounced decline than unreinforced products and more favourable maximum values.
The coefficient of linear thermal expansion is influenced by the fibre content and orientation: it is lower along the direction of the fibres.
A comparison with steel is significant: the linear thermal expansion coefficient of FRP is 1.5×10⁻⁵/°C, compared with 12×10⁻⁶/°C for steel. This is highly relevant both at the design stage and during installation, particularly when creating joints.
Is FRP resistant to chemical agents?
The main advantage of FRP compared with metals is the absence of corrosion.
The resin plays the most demanding role in chemical protection. Polyester resins offer different levels of resistance to chemical attack depending on their formulation: orthophthalic resins have good resistance to non-polar solvents, water, aqueous solutions and weak inorganic acids; isophthalic resins offer greater resistance to hydrolysis and a higher heat deflection temperature (HDT).
HDT indicates the maximum temperature at which the material can be used to manufacture mechanically loaded parts. It is based on a bending measurement performed on a standard test bar, loaded with a constant force while the temperature is gradually increased. The temperature at which a certain deflection is reached is called the HDT.
The glass transition temperature (Tg), on the other hand, is the temperature below which the resin is rigid; in our case, the higher it is, the more stable the resin remains as the temperature rises.
The maximum service temperature of the finished product is directly proportional to the Tg and HDT values of the resin used to manufacture it.
In conclusion, although chemical resistance mainly depends on the resin, other parameters must also be taken into account, including:
- the concentration of the chemical agent
- the service temperature
- the degree of mechanical stress
- the influence of the glass reinforcement
Is FRP resistant to loads and impacts?
The mechanical strength of FRP depends on the combined effect of the glass fibre reinforcement content and orientation, as well as on the type of resin and the accuracy of processing.
As the percentage of glass reinforcement increases, so does the breaking load — both in tension and bending — and impact resistance.
As for fibre orientation, maximum strength is achieved when all the strands are arranged parallel to one another (unidirectional layout); if the strands are arranged equally at right angles to each other, strength is lower but still considerable (orthogonal layout); if the strands are arranged with no preferential orientation, strength is equal in all directions (isotropic layout).
The more orderly the fibre arrangement, the higher the achievable glass content, and therefore the greater the mechanical strength.
The density of FRP is about 1/5 that of steel.
Mechanical strength ranges from 0.5 to several times that of steel, depending on the composition of the FRP and the orientation of the reinforcement within the composite. There are FRP formulations with strongly oriented reinforcement in which, along the main direction of the glass fibres, strength exceeds that of other materials even for the same cross-section.
The absolute elastic moduli of FRP are lower than those of metals; however, when considering the modulus-to-density ratio, strongly oriented structures can achieve values in the same order of magnitude as metals.
FRP also has considerable impact resistance, as it distributes the impact load and does not deform permanently, unlike steel, which can undergo permanent deformation (plastic phase).
Is FRP a thermal insulator?
Although it is not an excellent thermal insulator, FRP insulates 150–200 times better than steel and 700–800 times better than aluminium. Its thermal conductivity coefficient is very low compared with metals (FRP k = 0.22 W/m°C, STEEL k = 36–54 W/m°C).
Is FRP an electrical insulator?
FRP products have dielectric properties that make them excellent electrical insulators.
Tests for surface resistivity and electrical resistance Rs and cross-sectional Rt, resistivity and electrical safety resistance to earth (human body model), and dielectric strength at rated voltage showed resistivity greater than 200 MΩ and a current absorption of around 300 μA: the material can therefore be considered an excellent insulator, compliant with safety standards.
In the presence of electric current, FRP products should therefore be preferred over metal ones to ensure the safety of operators and users. Steel products, in fact, have high electrical conductivity (0.714 W/mm²m), with a possible risk of electric discharge and corrosion caused by galvanic currents.
To meet customer needs, however, FRP products can also be manufactured in a conductive version. Conductivity is achieved by adding CARBON BLACK to the resin, an additive obtained through the incomplete combustion of heavy petroleum products and consisting essentially of carbon.
Surface and cross-sectional electrical resistivity tests, carried out with a 10 V DC test voltage, showed that the samples have very low surface and cross-sectional electrical resistivity and can therefore be classified as excellent conductors.
Electrical safety tests carried out showed that the samples comply with the relevant standards (it is recommended to use resistances in the range of 1 MΩ to 5 MΩ).
A walking test was also simulated, using dissipative antistatic safety footwear, on the grating samples under test, both with and without an earth connection. In both cases, no electrostatic charge was generated. Both samples can therefore be fully classified as non-generators of electrostatic charge from foot traffic.
What is fibreglass?
Fibreglass is a composite material made of glass fibres impregnated with thermosetting resins, generally liquid and polyester-based, which harden after processing through the action of catalysts and accelerators.
It is a material also known as FRP or PRFV (from the Italian Polimeri Rinforzati con Fibre di Vetro), GRP (Glass-Reinforced Polymers) or GFRP (Glass Fiber-Reinforced Polymers), and GFK (from the German Glasfaserverstärkter Kunststoff).
Once produced, thermosetting polymers cannot be melted without undergoing chemical degradation (“charring”), unlike thermoplastic polymers, which are not permanently altered by processing and become workable again every time they are heated.
These are polymers that, under suitable temperature conditions and/or in the presence of specific substances, turn into rigid, insoluble and infusible materials. This transformation occurs through cross-linking reactions known as “curing”, which take place between the polymer chains, forming strong bonds.
What does FRP stand for?
Better known as fibreglass, FRP is a material made up of a matrix of thermosetting polyester resins reinforced with continuous glass fibres. The resin matrix ensures high corrosion resistance, while the glass fibre provides high mechanical strength, giving the composite chemical and mechanical characteristics that make it suitable for a wide range of applications.
It is a material also known as FRP (Fiberglass Reinforced Polymers), GRP (Glass-Reinforced Polymers), GFRP (Glass Fiber-Reinforced Polymers), GFK (from the German Glasfaserverstärkter Kunststoff), PRV (from the French Polymères Renforcés de Fibres de verre), and PRFV (from the Italian Polimeri Rinforzati con Fibre di Vetro and the Spanish Polímeros Reforzados con Fibra de Vidrio).
How are pultruded profiles manufactured?
M.M. also offers pultruded profiles, manufactured using the pultrusion technique. Pultrusion, from the English “pull” + “extrusion”, is a technology that allows composite products — even with a high reinforcement content — to be produced continuously, in simple or complex constant cross-section shapes.
The operating principle of this technology is simply based on applying a pulling force to the fibres, generally in roving form, forcing them to pass continuously through a heated die, where curing takes place, after they have been impregnated with the right amount of resin as they pass through an impregnation bath. The final shape is given to the component as it passes through the shaped die, where the material is not pushed through, as it is in conventional extrusion, but pulled through by the tension applied to it as it exits the die.
The pultrusion process requires continuous fibre reinforcement and a low-viscosity resin, generally a liquid thermosetting resin. The most commonly used fibre form is glass roving.
The basic process scheme consists of the following stages:
- reinforcement feeding
- impregnation
- preforming
- shaping and curing
- pulling
- cutting
- post-forming
How are fibreglass – FRP gratings manufactured?
How are fibreglass – FRP gratings manufactured? M.M.'s FRP gratings are manufactured using either RTM (Resin Transfer Moulding) technology, a closed-mould injection moulding process, or the HAND LAY-UP method with open-mould casting.
RTM (Resin Transfer Moulding) technology is used to manufacture polymer-matrix composites by transferring catalysed resin into a cavity shaped like the part to be produced, in which the dry reinforcement has been placed beforehand. The glass fibre is distributed orthogonally, which is very important for the mechanical strength of the finished product.
The cavity is created by closing the mould and counter-mould against each other. The mould matrix is sealed hermetically by a lid using a hydraulically operated system. Fully closing the mould ensures better, more complete curing, retaining most of the heat released by the reaction inside the matrix during the exothermic peak. In addition, the environmental impact is very limited.
The RTM manufacturing cycle consists of the following stages:
- mould cleaning
- application of the release agent
- positioning of the dry reinforcement
- closing and locking of the mould
- resin injection
- resin curing at a controlled room temperature
- mould opening and part removal
- finishing operations
- mould cleaning
- application of the release agent
- positioning of the pre-impregnated reinforcement
- full impregnation with catalysed resin (flood / wet-out)
- localised compaction
- hot curing of the resin at 80°C
- part removal
- finishing operations
What types of resins does M.M. use?
To manufacture its products, M.M. mainly uses polyester resins from the following categories: standard resins based on orthophthalic acid, resins with high corrosion resistance based on isophthalic acid, and vinylester resins. M.M. resins can be additivated to achieve self-extinguishing or electrically conductive properties.
The reasons behind the clear predominance of polyester resins in the production of M.M.'s FRP products can be found in the following characteristics:
- Excellent adhesion to the reinforcement and the possibility of low-pressure moulding. The use of other types of resins that require high pressures can cause fractures or even pulverisation of the fibres in some areas, reducing — and in some cases eliminating — the reinforcing effect of the glass material.
- Greater assurance of a more complete and even distribution of the resin.
- Curing can be carried out by dosing the catalyst and accelerator so that it is completed within the desired time frame.
- Low cost combined with high-level characteristics, especially in terms of mechanical, chemical and electrical resistance.
Fixed ladders: which technical standard applies?
The two standards cover the same physical object — the permanent fixed ladder — but have expressly disjoint fields of application. UNI EN ISO 14122-4:2016 (point 1) applies to fixed ladders that are part of a fixed machine, and to the same means of access when it is part of the building or civil structure, provided its main function is to allow access to the machine. UNI 11962:2024 (point 1) applies to permanent fixed ladders with an inclination greater than 75°, fixed to a support, used as a means of access to buildings, infrastructure, structures, works and plants, and expressly states that it does not apply to the fixed ladders covered by UNI EN ISO 14122-4.
The first design step is therefore not dimensional but one of qualification: what the ladder's main purpose is. Where it is located does not matter — a ladder on a roof may serve a machine, a ladder inside a plant may serve a building landing. The two standards are mutually exclusive: they must not be applied cumulatively.
A useful clarification. UNI 11962 is built on top of 14122-4, not against it: the Introduction states that “UNI EN ISO 14122-4 contains useful references that underpin this standard”, and for most requirements (rungs, loads, tests, stability checks) 11962 refers back to it verbatim. It is therefore best to reason in terms of the differences, not a full comparison.
Table 1 — Where the two standards diverge
From this point on, the analysis covers all the documentation required by 11962.
Table 2 — Documentation required by UNI 11962
Operational summary
| Aspect | UNI EN ISO 14122-4:2016 | UNI 11962:2024 | Design consequence |
| Definition of a fixed ladder (inclination) | 75° < angle of inclination ≤ 90° (UNI EN ISO 14122-1:2016, point 3.1, figure 1). Part 4 does not redefine the inclination: it refers back to Part 1. | Inclination greater than 75° (point 1). | No substantive difference: the 75° threshold is the same in both standards. |
| Requirement for fall protection | Mandatory if the total fall height is > 3,000 mm (point 4.2.1). Below this, the ladder may be without it. | Always present: fall protection is a constituent element of the very definition of “permanent fixed ladder” (point 3.15), and the classification in point 4 does not provide for a “without protection” class. | A 2.5 m ladder with no cage and no line is admissible in a machine context, but not under UNI 11962. Watch the title of UNI 11962: “with or without cage” means class S1, not “without protection”. |
| Type of protection and selection criterion | Two alternatives with an explicit hierarchy: the cage is the preferred choice because it is always present and independent of operator behaviour; the guided fall arrester is only effective if the user chooses to use it. The combination of cage + fall arrester is prohibited (point 4.2.2). | Two alternative classes with no declared hierarchy: S1 (guided-type fall-arrest device on a rigid anchor line, UNI EN 353-1) and S2 (safety cage) — point 4. The choice is made using tables A.1 and A.2 of Appendix A (normative). | In a machine context, the starting point is the cage, moving to the fall arrester only if the cage is not practicable. Outside a machine context, the choice is governed by h and H via tables A.1/A.2, which in practice greatly restrict the use of the cage. |
| Maximum rung length h with cage | h ≤ 6,000 mm for staggered flights (points 4.3.2 and 4.3.3). | h ≤ 5 m: class S2 is not permitted for h > 5 m (table A.1). | A 6 m flight with a cage: compliant with 14122-4, not compliant with 11962. |
| Maximum total height H with cage | No upper limit is specified. For H > 10,000 mm, staggered flights with a cage are permitted and, for untrained users, are the only ones permitted (point 4.3.3; the rule is not repeated in point 4.3.2, i.e. for 3,000 < H ≤ 10,000 mm). | H ≤ 20 m: “ladders fitted with a safety cage may be used up to a height H of 20 m” (point A.3); beyond this, class S2 is not permitted (table A.2). | Beyond 20 m, 11962 effectively requires class S1, and with it trained users, PPE and a rescue procedure. This is the constraint that most often changes the design. |
| Very low heights (H < 2.0 m) | No specific provision: below 3,000 mm of fall height, no protection is required. | S1 and S2 permitted “only if specified by the manufacturer” (table A.2). | For very low heights, 11962 leaves the choice to the manufacturer, who must nonetheless state it explicitly. |
| Intermediate platforms and landings — ladders with cage | Intervals ≤ 6,000 mm at each change of flight. The requirement is, however, doubly conditional: point 4.4.2 applies only to systems with H > 10,000 mm, and point 4.4.2.1 subordinates it to cases where more than one person uses the ladder at the same time. | Intervals ≤ 5 m both for H ≤ 10 m and for H ≤ 20 m, without the condition of simultaneous use (point A.3). | 11962 makes intermediate landings more frequent and turns them into a general requirement, not one subordinate to simultaneous use. |
| Rest platforms — ladders with guided fall arrester | H ≥ 24,000 mm: rest platforms at intervals ≤ 24,000 mm, with an additional intermediate platform ≤ 12,000 mm. H < 24,000 mm: rest platforms ≤ 12,000 mm (points 4.4.2.3 and 4.4.2.4). | H > 20 m: rest platforms at intervals ≤ 20,000 mm, with an additional platform ≤ 10,000 mm. H < 20 m: rest platforms ≤ 10,000 mm (point A.3). | A threshold at 20 m rather than 24 m, and a shorter interval. |
| Cage — distance from the plane of the rungs | from ≥ 650 mm to ≤ 800 mm (point 5.5.1.2, figure 15). | from ≥ 550 mm to ≤ 600 mm (point 7.5.3, figure 7). | The two cages are geometrically incompatible: the ranges do not overlap. A 600 mm deep cage is compliant with 11962 and out of tolerance for 14122-4; a 700 mm one, the opposite. |
| Cage — height of the lowest hoop above the starting area | ≥ 2,200 mm and ≤ 3,000 mm (point 5.5.1.2, figure 14). | ≥ 1,900 mm and ≤ 2,500 mm (point 7.5.3, figure 6). | Overlap zone: 2,200 – 2,500 mm. This is the range to adopt for a single product valid in both fields. |
| Frontal distance from permanent obstructions | In front of the ladder ≥ 650 mm, reduced to 600 mm where obstacles such as pipes or cable trays are crossed (point 4.1.3). | In front of the ladder ≥ 600 mm, reduced to 550 mm at pipes or cable trays (Appendix B, point B.3). | 11962 allows 50 mm less, to account for the tight spaces typical of roofs. Behind the ladder (≥ 200 mm, 150 mm with obstacles) and at the rungs (≥ 75 mm; top rung 60–75 mm) the values coincide. |
| Anti-intrusion device | Normative Annex A, with dimensional requirements and tests: door height ≥ 1,800 mm; free distance between the top of the door and the cage 10–50 mm, with an additional horizontal hatch; on ladders with fall arrest, the top of the device at ≥ 3,000 mm; release control between 600 and 1,800 mm from the walking surface. Tests: 1,500 N horizontal on each corner, 4,500 N vertical on the two bottom corners, a 50 kg spring-loaded body dropped from 2,000 mm onto the hatch. | Required in general terms when it is necessary to prevent access by unauthorised, untrained persons, or those not equipped with PPE; no dimensional requirement and no test (point 7.4.1). | This is a gap in 11962. In the absence of specifications, Annex A of 14122-4 remains the technical reference to adopt and to declare in the documentation. |
| Aspect | UNI EN ISO 14122-4:2016 | UNI 11962:2024 | Design consequence |
| Product designation and rated load | Not provided for: the ladder is a component of the machine and follows the machine's documentation. | Mandatory (point 5): product + UNI 11962:2024 + class S1/S2 + load in kg. Example from the standard: “Ladder without cage - UNI 11962:2024 - S1 - 150”. | 11962 treats the ladder as a stand-alone product: the designation must appear in the quotation, order confirmation, on the sign, and in the manual. |
| Marking and signage | Permanent marking at the entry and exit points only for systems fitted with a guided fall arrester: manufacturer, year, date of entry into service, reference standards, type of device, PPE obligation (point 7.2). | Marking of every component (symbol or identifying letter + year of manufacture) and a sign always mandatory at the starting or arrival area with manufacturer, year of manufacture, date of entry into service, designation, total height H and flight height h, reference to the manual (points 10.4 and 10.5). For class S1, EN 353-1 marking, type of line and device, reference to the harness, and the PPE obligation are also added. | A significantly broader set of documents, required in every case, not only for ladders with a fall arrester. |
| Inspection and maintenance | Not covered: falls within the machine's manual and maintenance plan. | Dedicated Chapter 9: inspection before assembly, on use, periodic and extraordinary; maximum interval 1 year for class S1 and 2 years for class S2; table 3 with checks per component (visual / functional / instrumental); repairs reserved to the manufacturer or a person authorised by them; inspection register with a defined minimum content (point 9.5). | This is the most useful difference from a management standpoint: 11962 provides a ready-made inspection plan, reusable as an attachment to the manual. |
| Rescue | Mentioned only as one of the factors in the risk assessment for choosing the device (point 4.2.3, letter e). | Normative Appendix C: the manufacturer must state in the manual the rescue procedures and the additional loads transmitted to the ladder; for class S2 with intermediate platforms, a gate and an anchor point available to the rescuer are mandatory. | To be incorporated both in the instruction manual and in the structural calculation (anchors, stiles, rungs, landings and platforms). |
| Fixing and supporting structure | Only the design loads: ≥ 3 kN on each stile for two-stile ladders, ≥ 6 kN on a single stile, transmitted conventionally to four anchor points (point 5.1.3.4). | Same loads (by reference) plus Informative Appendix D: minimum resistance classes of the supporting structure and type of fixing — timber C24 with screws (not nails), steel S235 with bolts, concrete C20/C25 with mechanical or chemical anchors; masonry and historic buildings assessed case by case by a qualified engineer. Point 10.2: information mandatory at the time of order regarding the installation site. | 11962 governs the interface with the existing structure, which in a machine context is not an issue because the support is the machine itself. |
| Verification methods | Generic list: measurement, visual examination, calculation and/or load test (point 6.1.1). | Table 2: a requirement-by-requirement matrix indicating which method (visual examination / measurement and calculation / test / documentary verification) applies to each point of Chapter 7. | Table 2 is effectively a ready-to-use acceptance checklist, also transferable to work carried out under 14122-4. |
| Legal status and conformity assessment | Harmonised standard under the Machinery Directive 2006/42/EC: the (informative) Annex ZA correlates the standard with essential requirements 1.5.15 and 1.6.2, and warns that the presumption of conformity requires the joint application of EN ISO 14122-1. The ladder is covered by the machine's CE marking. | Non-harmonised national standard: no presumption of conformity and no CE marking of the ladder product. It stands as good practice and the state of the art for the purposes of Legislative Decree 81/2008. | This changes the documentation logic: the machine's technical file on one side; the ladder manufacturer's declaration, manual, marking and sign on the other. |
- Qualify the access before sizing it. Does the ladder primarily serve a fixed machine (or a part of a building whose main function is to provide access to the machine)?
- Yes -> UNI EN ISO 14122-4, together with Parts 1, 2 and 3.
- No -> UNI 11962. The qualification must be put in writing and justified in the risk assessment: the two standards are mutually exclusive.
- Always verify the mandatory minimums of Legislative Decree 81/2008 (in particular Article 113 for fixed ladders over 5 m and with an inclination greater than 75°). The technical standard does not override the legislative requirement: in case of divergence, the mandatory requirement prevails.
- Size according to the values of the relevant standard, paying attention to the six points of genuine divergence: cage depth, height of the first hoop, maximum flight height and total height with cage, spacing of intermediate landings, reference standard for parapets, and frontal distance from obstacles.
- A single product valid in both fields. This is possible for almost all parameters by adopting the most restrictive requirement at every point: first hoop at 2,200–2,500 mm, h ≤ 5 m, H ≤ 20 m with cage, intermediate landings ≤ 5 m, frontal distance ≥ 650 mm, parapets compliant with both 14122-3 and EN 13374 class A. One parameter remains irreconcilable: cage depth, 550–600 mm under 11962 versus 650–800 mm under 14122-4. This is where the field of application must be decided, and two variants produced.
Which standard does the FIBERTOP composite cover comply with?
M.M.'s composite cover is designed and manufactured in accordance with EN 124:2015, “Gully tops and manhole tops for vehicular and pedestrian areas”.
EN 124:2015 defines the tests to be carried out on the products and the related methods, which may vary depending on the type of material used.
The tests required by the standard, to which the M.M. composite cover has been subjected, are as follows:
Dimensional check
A cover undergoes a visual inspection to check for the absence of defects. All the relevant measurements of the cover (clear opening diameter, frame height, seating depth, clearances, etc.) are then taken: all measurements must fall within the tolerances defined by the standard.
Residual deformation
A cover that has not previously undergone load testing is placed in the test equipment, and its initial position at its geometric centre is measured.
Using a punch of appropriate shape and size (the standard defines the shape and size according to the shape and dimensions of the part to be tested), a load equal to 2/3 of the test load for the relevant class is applied and then released. This procedure is repeated five times.
At the end, its position at the geometric centre is measured again: the difference between the two values determines the permanent deformation. This value must be lower than the limits set according to the load class and the size of the cover, as listed in the table below:
(1) If CO < 450 mm, this becomes CO/50, with a maximum value of 6.5 mm. (2) If CO < 300 mm, maximum value 1 mm. (3) If CO < 500 mm, maximum value 1 mm. The clear opening (CO) is defined as the diameter for circular covers, or the diameter of the largest inscribable circle for covers of other shapes.
Load resistance
Immediately after completing the permanent deformation test on the same cover, the test load is applied using the same test equipment.
The load must be held for 30 seconds and then released. The cover must show no visible signs of failure. The test loads are as follows:
Water and fuel absorption
Water absorption: after weighing a cover, it is immersed for 24 hours in deionised water at 23°C. Once removed, it is weighed again: the variation must be less than 0.3%.
Fuel absorption: after weighing a cover, it is immersed for 168 hours in diesel fuel at 23°C. Once removed, it is weighed again: the variation must be less than 0.3%.
After checking the weight variation, the covers are subjected to the load test and the permanent deformation test.
Creep
The test involves applying a load equal to 2/3 of the test load specified for the relevant class to a cover that has not previously been tested, and maintaining it for 60 minutes.
At the end of the 60 minutes, after a 5-minute recovery period, the residual deformation is measured, which must meet the same limits set out for the specific test.
The production process is classified as C3 in accordance with “Part 5: Gully tops and manhole tops made of composite materials”, i.e. manufactured using a temperature-controlled compression moulding process (SMC), using thermosetting resins, glass fibres and other additives.
| Class | Permissible permanent deformation |
| A15 and B125 | 1/100 (1) of the clear opening dimension |
| C250 to F900 | 1/300 (2) of the clear opening dimension |
| If fitted with a locking system | Secured with sufficient mass per area — 1/500 (3) of the clear opening dimension |
| Class | Test load (kN) |
| A15 | 15 |
| B125 | 125 |
| C250 | 250 |
| D400 | 400 |
| E600 | 600 |
| F900 | 900 |
How are FRP structures designed?
Structures using FRP profiles can be designed with reference to the CNR-DT 205/2007 Technical Document, “Guide for the Design and Construction of Structures made of FRP Pultruded Elements”. Its use for design purposes is permitted by the Technical Standards for Construction (NTC) published in 2018 (Chapter 12).
Further guidance on the design of FRP structures can be found in the technical specification “Design of fibre-polymer composite structures”, UNI CEN/TS 19101, available on the UNI website and currently subject to a trial period and related feedback: this marks the start of the final step towards it becoming, to all intents and purposes, the Eurocode for the design of fibre-reinforced polymer composite structures.
FRP structures are sized using the limit state method in the linear elastic range, taking into account the load combinations (paragraph 2.5.3, Combination of actions, of the Ministerial Decree of 17 January 2018) resulting from permanent loads, live loads, snow load, wind load and seismic action.
Thanks to their physical and geometric characteristics, M.M.'s FRP profiles integrate perfectly with steel accessories, usually AISI 316 stainless steel. For the design of the latter, connection checks on the FRP are carried out in accordance with the aforementioned CNR-DT 205/2007, relying on the usual Eurocode 3 and NTC 2018 for the steel-side checks.
Can FRP profiles be used for structural purposes?
The Technical Standards for Construction (NTC 2018) require that materials used for structural purposes must be identified, qualified and accepted by the Site Manager (Chapter 11).
The Standard provides that identification and qualification can be achieved, among other methods, as follows (11.1.c):
[…] the material or product must be CE marked in accordance with a “European Technical Assessment” (ETA) […]
Having completed the process of obtaining the ETA, M.M.'s FRP profiles can therefore be used for structural purposes and be accepted by the Site Management as well as by the Technical Services responsible for reviewing the calculation documentation.
It should be emphasised that CE marking does not apply to FRP material in general, but exclusively to M.M.'s FRP profiles.
To obtain CE marking for a product or material, it is necessary to apply to one of the TABs — Technical Assessment Bodies designated by the respective European Union Member States to draw up EADs and issue ETAs.
For FRP profiles, the applicable EAD (European Assessment Document) must be followed, which defines all the properties required for characterisation. Any manufacturer wishing to CE mark their FRP profiles with an ETA can choose which properties, among those listed in the EAD, to define and therefore test. They must also define all the profile sections to be characterised, both in terms of geometry and fibre composition.
Once these lists have been defined, experimental tests must be carried out to characterise the product, using accredited laboratories. M.M. has chosen to work with the renowned centre at the Politecnico di Milano.
Finally, once the experimental campaign is complete, the TAB proceeds to draw up the ETA, which declares all the profile sections with their dimensions and geometric properties, as well as the selected physical-mechanical properties, together with the corresponding values whose performance is to be guaranteed.
M.M. has obtained CE marking via ETA for a wide range of open and closed profiles, in numerous geometric dimensions and thicknesses: this allows it to meet the most varied needs, from small structures to structurally more demanding, large-scale projects. In addition, the average values of the mechanical properties meet the minimum requirements for Class E23 in accordance with UNI EN 13706.
Obtaining ETA certification also means guaranteeing the declared performance over time. To meet this commitment, M.M. submits its entire production process to constant, regular inspection by designated inspectors.
Specifically, M.M. is regularly monitored regarding the suitability of raw materials, in-line checks, equipment and instruments used, dimensional checks, and the composition of its products.
Do FRP structures meet workplace safety requirements?
Yes, and the question needs to be broken down into two parts, which have different answers.
The first concerns access — that is, the ladder, platform, walkway and parapet as such. Here, compliance is measured on two levels: Legislative Decree 81/2008, which is law and sets non-negotiable minimum obligations, and the UNI technical standards, which are not mandatory but represent good practice and translate those obligations into verifiable parameters. M.M. designs and manufactures its structural work in accordance with the UNI EN ISO 14122 series (Part 1, choice of means of access; Part 2, working platforms and walkways; Part 3, stairs, stepladders and guard-rails; Part 4, fixed ladders), which applies to permanent means of access to machinery and, where its main function is to provide access to the machine, also to parts of a building or civil structure.
The second concerns the material. Neither Legislative Decree 81/2008 nor the 14122 series prescribes steel: they impose performance requirements — strength, rigidity, stability, slip resistance, durability, the absence of sharp edges — and are neutral as to the material used to achieve them. FRP is therefore fully admissible, and is indeed the preferable choice where corrosion is the determining factor.
Table 1 — Legislative Decree 81/2008 and UNI EN ISO 14122 compared
Design summary
Four steps, in this order.
| Element | Legislative Decree 81/2008 | UNI EN ISO 14122 | Practical comparison |
| Nature of the obligation | Mandatory law, subject to criminal penalties. In fixed workplaces, breach of the Annex IV requirements is punishable under Article 68(1)(b): two to four months' imprisonment or a fine of €1,228.50 to €5,896.84. On construction sites, breach of Article 113 falls under the residual clause of Article 159(2)(c) — “provisions of Chapter II not otherwise sanctioned” — carrying up to two months' imprisonment or a fine of €614.25 to €2,457.02. | Voluntary technical standard. The 14122 series is harmonised with the Machinery Directive 2006/42/EC: compliance gives a presumption of conformity with the essential requirements for access to machinery. | The decree sets the non-negotiable minimum, the technical standard reflects the state of the art. Compliance with 14122 does not exempt from compliance with the decree: where the two diverge, the mandatory requirement prevails. |
| Parapets — height | A “standard” parapet has a clear height of at least one metre, is built of rigid, resistant material, has at least two rails, with the intermediate one at roughly half height, and is sized to withstand the maximum foreseeable force (Annex IV, point 1.7.2.1). With a toe board: a continuous strip resting on the walking surface, at least 15 cm high (point 1.7.2.2). | 14122-3 requires a minimum height of 1,100 mm, a handrail, an intermediate rail or equivalent elements, a toe board where necessary, limits on open gaps, and strength and deflection checks. | The technical standard is stricter: 1,100 mm versus 1,000 mm. It is advisable to adopt 1,100 mm as the minimum design reference, valid under both regimes. |
| Parapets — when required | On all open sides of scaffolding, walkways, platforms, access ramps, balconies and elevated work or transit areas (Annex IV, point 1.7.3). Protection is not required for loading platforms less than 2.00 m high. On construction sites, Article 126 requires a “sturdy parapet, kept in good condition” on all sides facing a drop of more than 2 metres. | 14122-3 requires a parapet where there is a fall risk of more than 500 mm, or when the lateral distance to an adjacent structure exceeds the specified limits. | Very different thresholds: 500 mm versus 2,000 mm. The technical standard applies much earlier. For machine access, the reference is 14122-3; the decree remains the minimum. |
| Fixed ladders — threshold and type of protection | Article 113(2) (construction sites): above 5 m and above 75°, a cage or fall-arrest PPE, as alternatives, based on the risk assessment. Annex IV, point 1.7.1.3 (workplaces): above 5 m or above 75°, a cage starting from 2.50 m, with an exemption for obstruction or construction difficulties. | 14122-4 requires fall protection when the total fall height exceeds 3,000 mm (point 4.2.1) and sets out a hierarchy: the cage is the preferred choice, with a guided fall arrester as the second option; combining the two is prohibited (point 4.2.2). | The decree applies above 5 m, the technical standard above 3 m: between 3 and 5 metres the obligation arises only from the technical standard. On the selection criterion the two texts are now at odds: the decree places the cage and PPE on the same footing, while 14122-4 favours the cage. |
| Fixed ladders — cage depth | The side of the cage opposite the plane of the rungs must not be more than 60 cm from them (Article 113(2) and Annex IV, point 1.7.1.4). This is a mandatory maximum. | The distance from the plane of the rungs to the cage must be between 650 mm and 800 mm (14122-4, point 5.5.1.2, figure 15). | Direct conflict. A cage sized according to 14122-4 breaches the Italian legal limit. This is why UNI 11962:2024 set the range at 550–600 mm: to stay within the 60 cm limit. For the Italian market the value to adopt is 550–600 mm. |
| Fixed ladders — height of the lowest hoop | Cage “starting 2.50 m from the floor or from the landings” (Annex IV, point 1.7.1.3). Article 113(2) no longer specifies this. | Lowest part of the cage between 2,200 and 3,000 mm above the starting area (14122-4, point 5.5.1.2). UNI 11962, on the other hand, specifies 1,900–2,500 mm. | Intersection of the three texts: 2,200–2,500 mm. This is the range to adopt for a product valid in every context. |
| Fixed ladders — rung-to-wall distance | The rungs must be at least 15 cm from the wall to which they are attached or to which the ladder is fixed (Article 113(2) and Annex IV, point 1.7.1.5). | Measured from the back of the rungs, behind the ladder: at least 75 mm, except for the top rung, which must be between 60 and 75 mm. Measured from the front of the rungs, behind the ladder: at least 200 mm, reduced to 150 mm where pipes or cable trays are crossed (14122-4, point 4.1.3). | The decree does not specify which face of the rung the measurement is taken from. If read from the back, the mandatory 150 mm is double the standard's 75 mm. Prudent design rule: 150 mm of clearance behind the rung, which satisfies both readings as well as the 200 mm measured from the front. |
| Stairs | Must withstand the maximum loads from emergency crowding; tread and riser sized in accordance with “good practice”, with a width suitable for transit; standard parapet on open sides; at least one handrail for flights between two walls (Annex IV, points 1.7.1.1 and 1.7.1.2; Article 113(1) for construction sites). | 14122-3 covers stairs with an inclination from 20° to 45° and provides the dimensional relationships: 600 ≤ g + 2h ≤ 660 mm, tread depth from 210 to 310 mm, ordinary minimum width 800 mm, up to 1,000 mm for simultaneous use. Stepladders cover the 45° to 75° range (14122-1, points 3.2 and 3.3). | The decree is performance-based and gives no numbers: it simply says “in accordance with good practice”. 14122-3 is precisely the document that translates that formula into verifiable parameters. Citing it in the technical file is the most direct way to demonstrate compliance with good practice. |
| Walkways and platforms | Walkways, platforms and elevated transit areas must be protected on open sides with standard parapets fitted with a toe board (Annex IV, point 1.7.3). On construction sites: a parapet above 2 m (Article 126); runways at least 0.60 m wide for passage only and 1.20 m for transporting materials, maximum gradient 50%, rest landings at intervals, and transverse cleats (Article 130). | 14122-2 governs working platforms and non-motorised walkways that are part of fixed machines: sizing based on use, transit and maintenance, slipping, tripping, openings, and side protection coordinated with 14122-3. | For machine walkways, 14122-2 applies, with parapets in accordance with 14122-3. Articles 126 and 130 remain central only for temporary construction-site works. |
| Strength, maintenance and checks | General obligation of safe construction, maintenance and upkeep: parapets built and fixed “so that they can withstand, as a whole and in every part, the maximum force to which they may be subjected, taking into account environmental conditions and their specific function” (Annex IV, point 1.7.2.1.4). No numerical value given. | Quantified loads and tests: 1.5 kN on the rung and 1.5 kN on the stiles; 1.5 kN per person on platforms; 6 kN vertical when the fall arrester is activated; 3 kN per stile on the anchors. Tests: 700 N on the stiles, 2,600 N on the rungs, 1,000 N on the cage hoops, with defined limits on residual deflection (14122-4, points 5.1 and 6). | This is where the technical standard adds the most value: it provides the figures needed to demonstrate that the decree's generic obligation has been met. The technical file should record the standard applied, dimensioned drawings, calculations and tests, instructions for use, maintenance, and inspection intervals. |
- Establish what the access is for. If it serves a machine, the UNI EN ISO 14122 series applies. If it serves a building, a roof, an infrastructure or a plant, the national standards apply: UNI 11962 for fixed ladders, UNI 11996 for parapets. The two paths are mutually exclusive, not cumulative. What matters is not where the ladder is located, but what it is for.
- Always use 14122 together with Part 1. Part 4 explains how to build a fixed ladder; Part 1 explains when it is permitted. First document why access from ground level is not practicable and why a stairway cannot be used — this is point 6.3.2 of Part 1 — and only then size the ladder using Part 4.
- Treat Legislative Decree 81/2008 as a design constraint, not a final check. The relevant section must be identified immediately: Annex IV, point 1.7, for factories and fixed workplaces; Title IV, Chapter II, for construction sites.
- Manage the differences between the law and the technical standard by knowing which way they tip.
- When the technical standard demands more than the law — a 1,100 mm parapet instead of 1,000, fall protection above 3 metres instead of 5 — there is no problem at all: the standard is applied and the legal minimum is automatically exceeded.
- When it is the law that demands more — a cage no more than 600 mm from the plane of the rungs versus the 650–800 mm of 14122-4, rungs 150 mm from the wall versus 75 mm — the law is followed.
What environmental labels does M.M. hold?
Environmental labels are voluntary tools that help communicate the environmental characteristics of products or services in a transparent and verifiable way. The reference standard is ISO 14020:2022, which defines three main types of labels:
- Type I Environmental Labels — ISO 14024
- Type II Environmental Labels — ISO 14021
- Type III Environmental Labels — ISO 14025
Where do M.M.’s production offcuts and processing waste go?
M.M. carefully manages the offcuts generated during processing: wherever possible, these materials are sorted and reused in future orders, with a view to efficiency and waste reduction. Where recovery is not feasible, offcuts, together with non-reusable waste, are sent to waste-to-energy plants, where they are converted into energy.
Does M.M. have a sustainability rating?
M.M. has chosen to use the EcoVadis rating, one of the leading international standards for assessing corporate sustainability, in order to measure its ESG performance in a structured and independent way.
EcoVadis provides a detailed analysis of performance in four key areas:
- Environment
- Labour practices and human rights
- Ethics
- Sustainable procurement
Does M.M. calculate its own carbon footprint (GHG)?
As part of its sustainability journey, M.M. has calculated the carbon footprint of its operations in accordance with the GHG Protocol criteria, as an integral part of its ESG assessment.
The GHG Protocol (Greenhouse Gas Protocol) provides an international standard for classifying greenhouse gas (GHG) emissions and defining their sources. Emissions are divided into three main categories:
Scope 1 — Direct Emissions
These are the direct emissions generated by sources owned or controlled by the organisation, such as production plants, boilers or company vehicles.
Scope 2 — Indirect Energy Emissions
These include the indirect emissions associated with the generation of purchased energy (electricity, heat, steam, cooling) consumed by the organisation.
Scope 3 — Indirect Emissions in the Value Chain
These include all other indirect emissions, both upstream and downstream, resulting from activities such as: transport, business travel, supplies, product use and disposal, etc.
Does M.M. apply the principles of the circular economy?
The circular economy is a model of production and consumption aimed at extending the life of materials and products for as long as possible. Unlike the traditional “take — make — use — dispose” model, the circular economy is based on principles such as reuse, repair, refurbishment and recycling, minimising waste and environmental impact.
The aim is to create a virtuous cycle in which resources remain within the economic system for as long as possible.
In this respect, fibreglass products stand out for their durability. They withstand wear, weathering, chemicals and corrosion over time without losing their properties. This means they generally do not need to be replaced, reducing resource consumption and waste generation.
Fibreglass products also require minimal maintenance. Unlike other materials that require painting, anti-corrosion treatments or specific protective measures, fibreglass retains its structural and aesthetic properties with limited intervention. Less maintenance means less use of chemical products and a lower environmental impact throughout the product's life cycle.
In line with circular economy principles, M.M. optimises the management of production offcuts, which are sorted and then reused in future orders.
In addition, M.M. offers a surface regeneration service for FRP gratings, which includes:
- cleaning and removal of dirt,
- repainting or reapplication of the anti-slip finish (quartz coating).
Is fibreglass recyclable?
Fibreglass, being a composite material (glass fibre reinforced with polymer resin), is not easily recyclable in traditional recycling plants. However, there are innovative technologies that make it possible to recover glass fibres from end-of-life products, separating them from the resin so they can be reused in new production processes. These technologies are available at different levels of technological maturity, and not all of them are available on an industrial scale.
To date, the main technology for recycling composite materials is through cement production kilns (also known as co-processing), in which the waste partly becomes part of the cement's composition and partly acts as fuel.
Composite materials can also be recycled through mechanical and electromechanical recycling (high-voltage pulse fragmentation), or through thermal recycling processes (pyrolysis, fluidised bed and depolymerisation) or thermochemical processes (solvolysis).
Co-processing is an innovative technology used in cement plants that makes it possible to valorise fibreglass-based waste within the cement production process. This method is specific to materials containing glass fibres and is not suitable for treating composites reinforced with carbon fibres.
In co-processing, the glass fibres and inorganic fillers present in composite materials partly replace the raw materials (such as calcium carbonate) normally used to produce clinker. At the same time, the resin component is used as an alternative fuel to traditional fossil fuels, such as pet coke.
This dual function makes co-processing a process that is:
- efficient (materials and fuels are valorised simultaneously),
- scalable,
- fast.
- the use of already decarbonised raw materials, such as the calcium oxide present in glass fibres, which avoids the CO₂ release associated with the decomposition of mineral calcium carbonate;
- the optimal dispersion between resin and mineral filler, which improves combustion efficiency and optimises the kiln's energy performance.
- short fibres, which can be reused as reinforcing elements;
- polymer matrix powder, which can be used as a filler.
- furniture products,
- industrial components,
- solutions where the recycled material performs a secondary structural function.
- glass fibres still undergo a loss of quality, due to the removal of the surface sizing (essential for adhesion to the original matrix);
- exposure to high temperatures can further damage the fibres, reducing their mechanical strength.
- requires high initial investment,
- has higher operating costs compared with other recycling methods.
- reduces the risk of damage to the fibres,
- better preserves the original mechanical properties.
- good industrial scalability, but also involves:
- high initial investment,
- significant operating costs,
- a potential environmental impact that must be carefully managed, particularly in relation to the handling of the solvents used.
- the polymer matrix of the composite materials is decomposed mainly into gaseous products,
- these gases are recovered and used to generate energy within the same process.
- painted laminates,
- materials bonded to foams or other substrates.
- preserve fibre integrity, resulting in longer, cleaner fibres compared with those obtained using traditional mechanical techniques (such as grinding),
- minimise contamination between matrix and reinforcement during separation.
- amounts of electricity,
- significant investment, both for the plant and for operations.
- does not require the use of aggressive chemical reagents,
- produces a reusable organic liquid fraction,
- can treat complex composites, including those containing core materials (such as PS, PU, PET), metal inserts or wood (e.g. balsa).
- Matrix depolymerisation — In the presence of CO₂, the polymer decomposes at molecular level, producing condensable vapours which, once purified, generate an organic liquid compatible with virgin resins (unsaturated polyester, vinylester or epoxy). This liquid can be blended and re-polymerised, contributing to the production of new composite materials. In some cases, it is also possible to recover valuable chemical compounds, such as phthalic anhydride.
- Calcination of the solid residue — In this phase, the remaining organic residues are eliminated, and the reinforcing fibres and any inorganic fillers are recovered.
- Recovery of both composite components (fibres + matrix)
- Direct compatibility with virgin resins
- Sustainable treatment, thanks to the reuse of CO₂ and the absence of toxic reagents
- More cost-effective than other thermal processes, thanks to the high yield of reusable product
Are M.M. products compliant with the REACH regulation?
M.M.'s FRP products are designed and manufactured in full compliance with Regulation (EC) No. 1907/2006 (REACH), which governs the use of chemical substances.
M.M. products are classified as “articles” under the regulation. This means that M.M.'s main obligation is to ensure that the materials they are made of do not contain hazardous chemical substances above the legal limits.
How does M.M. ensure compliance?
- Ongoing dialogue with suppliers: M.M. actively collaborates with its raw material suppliers (resins, glass fibres, additives, etc.) to ensure that no restricted substances (listed in Annex XVII of REACH) are present in M.M. products.
- Monitoring of Substances of Very High Concern (SVHC): M.M. verifies that its articles do not contain Substances of Very High Concern (SVHC) in concentrations above 0.1% of the product's weight. These are substances that can have serious effects on health or the environment.
- Continuous updates: the European Chemicals Agency (ECHA) periodically updates the list of these substances (the “Candidate List”). M.M. constantly monitors these updates to ensure ongoing compliance and to fulfil all communication obligations along our supply chain.
Do M.M. products comply with the CAM (Minimum Environmental Criteria)?
The CAM (Minimum Environmental Criteria) are mandatory environmental requirements in public procurement, designed to guide more sustainable choices throughout the entire life cycle of products, services and projects.
In Italy, compliance with these criteria is required under the Public Contracts Code (Legislative Decree 36/2023), which mandates their application in tenders, both in technical specifications and in award criteria. This obligation ensures that national policy is effective, not only in reducing environmental impact, but also in promoting more sustainable and circular production and consumption models. At present, the construction-sector CAM do not include technical specifications directly applicable to M.M. products.
However, in order to make designers more aware of the environmental impact of M.M. products, the company has chosen to obtain an Environmental Product Declaration (EPD) for its profiles, developed in accordance with UNI EN ISO 14025:2006 and validated by a third-party body.
This is a concrete step towards providing certified, transparent and comparable environmental data.
Through this tool, M.M. has also been able to identify the main areas for environmental improvement along the product life cycle, thereby strengthening its commitment to increasingly conscious, traceable and sustainability-oriented production.
