Gratings
Gratings are a type of covering or frame that features a textured surface created by holes, openings or a grid pattern formed by bars.
Quick links to Gratings Information
The History of Gratings
The production and use of grates stretches back to the Bronze Age. For example, between the third and fourth centuries BC, residents of the colonized Roman city of Elea (later: Velia) built a street featuring a small gutter for drainage. This is just one of the countless examples of grate use in antiquity. Grates were also important during the advent of home heating; their use in fireplaces came about in the 11th century, when users found that they were especially useful for holding coal.
Older grate models, such as wall grates, were made from metal like iron or steel. They could have been square or rectangular, but were often also arched or round. Some were extremely large. Today, grates are more often made from thermoplastic bars or aluminum bars, as they are less expensive to produce. Also, they often feature angled openings or pins for an airflow that you can direct. Antique gratings still have a place in society, though, as both antique collectors and those involved in historic building preservation find them to be quite valuable. Others seek them out for their aesthetic appeal.
Modern grates are much more varied than their predecessors, not just in material but also in design and application, offering those uses that we mentioned in the last section, and more. Engineers continue to innovate in order to make them more effective, durable and sustainable.
Advantages of Gratings
Gratings offer a lot of advantages. First, when applied to the floor, their installation offers increased traction and tread, leading to increased workplace safety. Also, they often help fulfill regulation standards in certain areas of a factory or warehouse, including areas near potential fluid or lubrication leaks or as part of stairs and high walkways. They also provide slip resistant areas and extra grip for vehicles such as forklifts and other machinery and equipment. Aside from safety, they also increase the efficiency and effectiveness of processes like draining.
Grating manufacturing also offers many advantages, including design flexibility, material versatility, and a wide range of sizes and thicknesses.
Design of Gratings
- Production Process
- To make grates, manufacturers either use metal plate expansion, perforation, molding, pultrusion, or welding. During expansion, manufacturers slit and expand metal to their desired dimensions. Metal plate expansion is popular because it generates minimal waste. During perforation, gratings manufacturers use a punching press to create hole patterns. These methods are used to make metal gratings. To strengthen metal gratings, manufacturers can finish them off with hot dip galvanization. Hot-dipped galvanized gratings are hot-dipped in a layer of zinc oxide, which protects the metal from elements that lead to corrosion, oxidation, weakening and an overall shorter life span.
- When manufacturers want to make plastic or fiberglass (frp) gratings, they turn to molding and pultrusion. During plastic grate molding, suppliers first manually layer the materials to be molded, allowing them to determine and control grate thickness and dimensions. Then, they put the grate in a mold, where they cure. Once done, they’re ready for installation. This process is popular because fiberglass molds can be reused and are being cleaned and prepared.
- Pultrusion is a lot like extrusion. The difference is that, instead of being pushed through a die, the impregnated bar resins are pushed through the die. Most often, this method makes pultruded fiberglass grates. Frp pultrusion significantly reduces material waste and can be used to meet a wide range of sizes, dimensions and layouts. While molding has a strong manual element to the formation process, pultrusion is an automated procedure that results in consistent and high-quality products.
- Alternative to all of these, metal bar gratings and fiberglass bar gratings are welded, swaged or riveted together in a rectangular configuration or grid pattern. Each bearing bar is welded with each cross bar so they fuse and form a permanent joint. This ensures a high degree of rigidity for the production of walkways, platforms, safety barriers and trench grates.
- Material Design
- Gratings can be made from many different materials. Common materials include: aluminum, iron, carbon steel, weld steel, alloy stainless steel, fiberglass and reinforced plastic. Metal grate products, typically aluminum grate, carbon steel grate or stainless steel grate, are used for surface filtration, support of non-slip surfaces and general high strength applications. Meanwhile, materials like fiberglass and plastic are usually made to make floor gratings, drain grates and architectural grates. Plastic grating or fiberglass grating, is used as an alternative to metal grating because: it is lighter (even than aluminum), easy to install, slip-free, doesn't rust and remains fire retardant.
- Design Considerations
- Depending on the corrosive nature of the building's environment and the needed load strength, floor gratings are manufactured in various thicknesses, bar dimensions and grip patterns. The available patterns of openings in floor gratings vary from diamond shape to oval, and each pattern has different inherent strength properties. The choice of pattern of floor gratings is both practical and aesthetic, as some grates are used for architectural purposes. However, structural soundness and practicality are most important, as the percent of open area is related to the amount of light, water, air and sound that is able to pass through the grating. The most heavy-duty floor gratings are those made out of welded or pressure-locked interlocking bars.
- To customize your gratings, your custom manufacturer can invest cast your grating, allowing for more complex patterns. They can accommodate virtually any unique specifications relating to: opening shapes, opening sizes, bar spacing, metal bar strength-to-weight ratio, bar thicknesses and bar dimensions.
Grating Types
- Architectural Grates
- A metal or fiberglass reinforced plastic lattice incorporated in building design for a number of functional and aesthetic purposes.
- Aluminum Grating
- A framework made using alloyed aluminum bars, sheets and meshes to create a porous grid that may be used for a variety of industrial, commercial and domestic purposes.Aluminum is a popular grate material as it has excellent corrosion resistance under a variety of service conditions, light mass and high strength-to-weight ratio.
- Covered Grating
- A durable, molded fiberglass floor product combining slip resistant floor plates and molded grating.
- Drain Grates
- An essential component of drainage systems which allow the passage of fluids while capturing debris which may clog or otherwise damage piping.
- Expanded Metal Grating
- Lightweight, durable and inexpensive, provides some traction and does not need special equipment to be installed. The openings range from 3/16" to 2".
- Floor Gratings
- Encompass a wide variety of grates used for flooring or as supplements to improve flooring characteristics such as grip.
- Galvanized Gratings
- Zinc coated in order to improve strength and corrosion resistance in industrial, commercial and domestic applications where grates are exposed to corrosive materials or are in high use.
- Metal Grates
- The norm in the floor grating world. The metals used most often are stainless steel and iron, but aluminum is sometimes used in lighter traffic and load situations.
- Perforated Metal
- A type of metal fabrication technique which punches holes of various sizes and patterns via a punching press. This type of metal is often used along with expanded metal to create floor gratings.
- Plastic Grating
- Never 100% plastic but is often reinforced with fiberglass.
- Pressure Locked Grating
- Offers the widest variety of load bearing bar spacing and can be manufactured efficiently in small quantities. Pressure locked grating is one of the most versatile types of grating.
- Stainless Steel Grates
- Made using alloyed steel bars, sheets and meshes to create a porous grid that will not rust, corrode or stain easily and may therefore be used in harsh environments and applications involving volatile fluids and gases.
- Welded Grating
- Formed by electrically fusing cross bars to steel load bearing bars.
- Bar Grate
- Known for strength, bar gratings are most often made of metal as it is able to withstand higher traffic and impact than fiberglass or plastic. They consist of metal bars machined together. The load bearing bars are positioned vertically an equal distance apart and joined by cross bars to form a rectangular pattern. Bar gratings are used for walkways, platforms, mezzanine decking, stair treads and more.
- Stair Tread
- Usually made from perforated metal or expanded metal. They feature cut-out holes and serrated teeth, a grid pattern or textured surfaces that deter slipping and the buildup of water, mud or other materials. Their slip resistance makes them perfect as stair covers, ladder covers, or as stairs and ladders themselves.
- Trench Gate
- Long and narrow bar grating drain covers that allow pedestrians to walk over them, are popular grating products found all over on city streets and sidewalks. They accommodate drainage and deter water buildup. They come in many styles and designs, and may merely sit on top of the drain or be bolted down.
- Fiberglass Grate (FRP Grate)
- Offers higher strength than other plastic grating types due to the addition of glass fibers. For that reason, and because it is highly corrosion resistant and heat resistant, plastic grating is almost always made with fiberglass. It is the strongest type of floor grating, often used to produce floors, stairs and enclosures.
- Steel Grate
- This type of metal grate is strong and durable, and so it works well with many applications. For highly corrosive environments, manufacturers can offer galvanized steel grates.
Grating Applications
Manufacturers produce gratings for a wide variety of important building and construction applications, including: increased traction and tread, drainage, separation, ventilation and airflow and sunshade. They’re also used as louvers, decorative and ornamental screens, fencing, handrails, perforated walkways, and in pedestrian walkways to cover narrow sewers and drains so they may be walked over.
Because gratings are important elements of workplace and home safety, they are sought after by many industry customers, including those in: food and beverage, building construction, industrial manufacturing, HVAC, mining, water treatment and plumbing and hygiene.
Grating Installation
While each situation is different, we can offer some basic advice for installing your grates.
- Make sure that you install your grating with the cross rods on the top side. Do this in order to achieve strength specifications.
- For the most strength, use metal for all your grating supports.
- A minimum of 1" bearing shall be provided for bearing bar depths up to 2-1/4"; 2" minimum bearing shall be provided for bearing bar depths of 2-1/2" or greater.
- Maintain clearances in accordance with dimensional tolerances.
- Make sure that any cutouts for circular obstructions are at least 2 inches larger in diameter than the obstruction.
Standards and Specifications for Grates
One of the ways that consumers can evaluate grating compatibility and quality is via their ASTM grade. ASTM International has developed safety and quality standards for nearly everything, including different types of gratings, such as FRP gratings used in marine construction and shipbuilding (ASTM F 3059-15), and the materials and processes used to make them (steel quality, hot-dipping, galvanization, etc.). We highly recommend that you 1) make sure your product has been evaluated and assigned an ASTM quality standard grade, and 2) make sure its grade matches your requirements.
Things to Consider When Purchasing Gratings
To get the best grating for your application, with the right amount of strength, durability, stability and corrosion resistance, work with an experienced grating supplier. A supplier can guide you through the complex world of grating materials, patterns and processes.
Not sure where to start? No worries! IQS has compiled a list of our top grating manufacturer picks. All of those listed are reliable and hardworking. To find out which one among them is the right company for you, browse their websites, make note of those that appear to have services closest to your needs, and then reach out to three or four of them. Make sure to ask them all the same questions, which should relate to lead times, delivery capabilities, budget, standard specifications and customization. Compare and contrast the answers that each one of them gives you, and then go with the manufacturer that you believe will provide you with the best customer service within your budget. There’s someone out there for everyone.
Proper Care for Gratings
To keep your grating products effective and serviceable, we recommend that you clean them regularly. Slip resistant gratings must be cleaned especially often, in order to stop the accumulation of residue or buildup that can smooth over its texture.
Most grates can be cleaned by standard cleaning products, but they vary from product to product. For example, to remove grease and oil, organic enzyme and alkaline based cleaning agents work well for some steels, but blacken the surface of others, like stainless steel. Also, if your stainless steel grate rusts, we recommend you clean it with diluted muriatic acid, concentrated no more than one-part acid to one-part water. To get advice on the best cleaning products for your particular product, talk to your supplier.
Tools you can use to dislodge bits of debris, depending on your grate style, include soft bristle brushes and compressed air cans. For heavy sludge or grime accumulations, you may need to tend to your grating with a power washing or a stiff bristle brush.
Grate Accessories
To make sure your grating system is ready to take on anything, get the necessary accessories. These include items like: fasteners, locks, bolts, hold down clamps, hold down clips, anchor plates, washers, butterfly clips and channel connectors. Learn which ones are right for you by talking to your grating supplier.
Grating Terms
- Anchor
- The device by which grating is attached to its supports.
- Bearing Bars
- Load-carrying bars made from steel strip or slit sheets or from rolled or extruded aluminum and extending in the direction of the grating span.
- Bond
- The intersection of two strands in a grating pattern.
- Carriers
- Flats or angles which are welded to the grating panel and nosing of a stair tread.
- Cross Bars
- The connecting bars that extend perpendicularly across the bearing bars. Where cross bars intersect the bearing bars, they are welded, forged or mechanically locked to the bearing bars.
- Cutout
- A section of grating that has been removed to allow pipes, ducts, columns, etc. to pass through the grating.
- Grating
- An open grid assembly of metal bars, in which the bearing bars running in one direction are spaced by rigid attachment to cross bars running perpendicular to them or by bent connecting bars extending between them.
- Grating Frame
- A metal frame that contains floor grating and provides a means to anchor floor construction.
- Grating Tread
- The surface of a step constructed of a type of grating.
- Hinged Panels
- Grating panels which are hinged to their supports or to other grating parts.
- Kick Plate
- A flat bar attached flat against the outer edge of a grating and projecting above the top surface of the grating to form a lip or curb.
- Nosing
- A special L-section member serving as the front or leading edge of a stair tread or of grating at the end of a stair.
- Reticuline Bar
- A sinuously bent connecting bar extending between two adjacent bearing bars, alternately contacting and being riveted to each.
- Rivet Centers
- The distance center to center of rivets along one bearing bars.
- Reversible Grating
- Grating so constructed that it may be installed either side up.
- Span of Grating
- The distance between two points of grating support.
- Straight Cut
- That portion of the cut edge or cutout of a grating which follows a straight line.
- Trim Band
- A band that is not load-carrying but primarily used for aesthetic purposes.
- Width
- The overall dimension of a grating panel, measured perpendicular to the bearing bars.