Introduction: An Unreadable Code, a Wasted Order
“G255/30/100S” – when you first see this string of characters on a steel grating specification sheet, do you feel completely confused?
In industrial procurement, steel grating is a product that seems simple but is easily “misunderstood”. Its selection is not like buying office supplies where “just look at the price”. Instead, it follows a rigorous technical language – every number and every letter in the type designation corresponds to specific bearing bar dimensions, grid spacing, manufacturing process, and surface treatment. Understanding it ensures that the product you order meets the engineering requirements.
Regulation 11 of Singapore’s Factories (Scaffolds) Regulations clearly stipulates that all planks forming a working platform must be capable of sustaining a load of 670 kilogram-force per square metre having regard to the distance between the supports thereof, and metal plates must be provided with a slip-resistant surface. This means that the selection of steel grating is not only a matter of parameter matching but also a fundamental requirement for compliance and safety.
This article is based on China’s ferrous metallurgy industry standard YB/T 4001.1-2019 “Steel Grating Bars and Matching Parts Part 1: Steel Grating Bars” and Singapore SS 363:2014 “Specification for steel gratings for roads, drains and walkways”. It breaks down each component of the steel grating type designation for non-professional buyers, helping you avoid confusion when placing orders.
Chapter 1: The Composition System of Steel Grating Type Designations
1.1 Standard Type Designation Format
According to YB/T 4001.1-2019, the type designation of steel grating consists of multiple parts, comprehensively reflecting key information such as bearing bar dimensions, grid spacing, structural type, bar profile, and surface treatment condition.
Standard designation format:
G [bar size] / [bar spacing] / [cross bar spacing] [structural type] [bar profile] [surface treatment]
Some parts may be omitted under certain conditions to simplify the designation.
1.2 Quick Reference Table for the Meaning of Each Part
| Position | Marking | Meaning | Common Example | Omissible? |
|---|---|---|---|---|
| First | G | Steel grating code | G | Fixed code, not omitted |
| Second (first number group) | Bar size | Bearing bar width × thickness (mm) | 255 (i.e., 25×5mm) | Not omitted |
| Third (middle number group) | Bar spacing | Center-to-center distance between adjacent bearing bars (mm) | 30, 40 | Not omitted |
| Fourth (last number group) | Cross bar spacing | Center-to-center distance between adjacent cross bars (mm) | 50, 100 | Not omitted |
| Structural type | W / L | W = pressure-welded steel grating, L = press-locked steel grating | W can be omitted, L must be marked | W can be omitted |
| Bar profile | F / S / I | F = flat, S = serrated, I = I-section | F can be omitted, S must be marked | F can be omitted |
| Surface treatment | G / P / U | G = hot-dip galvanized, P = painted, U = untreated | G can be omitted | G can be omitted |
YB/T 4001.1-2019 was issued on 27 August 2019 and came into effect on 1 January 2020, completely replacing the 2007 edition. This standard applies to steel grating bars used for working platforms, walkways, stair treads, and cover plates in industries such as petroleum, chemical, metallurgy, shipbuilding, energy, and municipal engineering.
Chapter 2: Detailed Explanation of Each Part – Breaking Down Every Character
2.1 First Part: The Letter "G" – Identity Mark of Steel Grating
The “G” at the beginning of the type designation stands for “Grating” (steel grating) and is the basic identifier for steel grating products. Regardless of the specification, the type designation always starts with “G”. For example: G323/30/100, G255/30/100S, etc.
2.2 Second Number Group: Bar Size – The Core Determining Load Capacity
The first number group after “G” represents the cross-sectional dimensions of the bearing bar – width × thickness (in millimetres). This is the most critical parameter in the type designation, directly determining the load capacity of the steel grating.
Example interpretation:
| Type | Bar Width | Bar Thickness | Load Characteristics |
|---|---|---|---|
| G253/30/100 | 25mm | 3mm | Light duty, suitable for pedestrian walkways |
| G255/30/100 | 25mm | 5mm | Medium duty, increased thickness for higher load |
| G323/30/100 | 32mm | 3mm | Medium duty, suitable for general platforms |
| G325/30/100 | 32mm | 5mm | Medium-heavy duty, common for industrial platforms |
| G405/40/150 | 40mm | 5mm | Heavy duty, suitable for equipment platforms |
Example: In the type G255/30/100S, “255” means the bearing bar dimensions are 25mm × 5mm.
Selection tip: The greater the bar height and thickness, the higher the load capacity. For the same support spacing, a 40×5mm bearing bar has approximately 2.8 times the load capacity of a 25×3mm bearing bar.
2.3 Third Number Group: Bar Spacing – Affecting Water Permeability and Prevention of Small Object Falls
The middle number indicates the center-to-center distance between adjacent bearing bars (in millimetres). Common bar spacings are 30mm and 40mm. Additionally, by series classification: Series 1 spacing is 30mm, Series 2 spacing is 40mm, Series 3 spacing is 60mm.
| Bar Spacing | Characteristics | Application Scenarios |
|---|---|---|
| 30mm | Strong prevention of small object falls, relatively lower water permeability | Crowded walkways, areas with fall prevention requirements |
| 40mm | Better water permeability, higher drainage efficiency | Drainage channel covers, outdoor platforms |
| 60mm | Highest water permeability, weak fall prevention | Special drainage requirements |
Example: In the type G255/30/100S, “30” means the bar spacing is 30mm.
2.4 Fourth Number Group: Cross Bar Spacing – Affecting Lateral Stability
The last number group indicates the center-to-center distance between adjacent cross bars (twisted square bars or flat bars) (in millimetres). Common cross bar spacings are 50mm and 100mm.
| Cross Bar Spacing | Characteristics | Application Scenarios |
|---|---|---|
| 50mm | Stronger lateral stiffness, denser grid | Heavy load areas, forklift aisles |
| 100mm | Standard configuration, most widely used | Most industrial platforms |
Example: In the type G255/30/100S, “100” means the cross bar spacing is 100mm.
2.5 Suffix Letters: Structural Type, Bar Profile, and Surface Treatment
The suffix letters provide additional information about the product:
Structural type:
W: Pressure-welded steel grating (can be omitted in designation)
L: Press-locked steel grating, fixed by pressing cross bars into slotted bearing bars (must be marked)
Bar profile:
F: Flat bearing bar (can be omitted in designation)
S: Serrated bearing bar, with serrated teeth on the surface for slip resistance
I: I-section bearing bar
Surface treatment:
G: Hot-dip galvanized (can be omitted in designation)
P: Painted
U: Untreated
Example: In the type G255/30/100S, “S” indicates serrated bearing bar. If the type is G255/30/100 with no suffix, it defaults to flat bar (F) and hot-dip galvanized (G).
Chapter 3: Complete Type Designation Examples
3.1 Example 1: G323/30/100
| Part | Meaning | Interpretation |
|---|---|---|
| G | Steel grating | Product type identifier |
| 323 | 32mm×3mm | Bar width 32mm, thickness 3mm |
| 30 | 30mm | Bar spacing 30mm |
| 100 | 100mm | Cross bar spacing 100mm |
| (no suffix) | Default | Pressure-welded (W) + flat (F) + hot-dip galvanized (G) |
This is a pressure-welded flat-type hot-dip galvanized steel grating, suitable for general industrial platform walkways.
3.2 Example 2: G405/40/150L
| Part | Meaning | Interpretation |
|---|---|---|
| G | Steel grating | Product type identifier |
| 405 | 40mm×5mm | Bar width 40mm, thickness 5mm |
| 40 | 40mm | Bar spacing 40mm |
| 150 | 150mm | Cross bar spacing 150mm |
| L | Press-locked | Press-locked process (cross bars are flat bars) |
This is a press-locked hot-dip galvanized steel grating (G omitted) with larger bar dimensions, suitable for heavy load areas. According to the marking example in YB/T 4001.1, the typical designation for press-locked steel grating is G405/40/50L.
3.3 Example 3: G255/30/100S
| Part | Meaning | Interpretation |
|---|---|---|
| G | Steel grating | Product type identifier |
| 255 | 25mm×5mm | Bar width 25mm, thickness 5mm |
| 30 | 30mm | Bar spacing 30mm |
| 100 | 100mm | Cross bar spacing 100mm |
| S | Serrated bar | Surface with anti-slip serrations |
This is a serrated slip-resistant steel grating, with a serrated surface, suitable for wet or oily environments where slip risk is present.
Chapter 4: Singapore Standards and Regulatory Requirements for Steel Grating
4.1 Load Requirement: Mandatory Provision of Singapore Factories Regulations
Regulation 11 of Singapore’s Factories (Scaffolds) Regulations 2004 stipulates:
All planks forming a working platform must be capable of sustaining a load of 670 kilogram-force per square metre having regard to the distance between the supports thereof
Metal plates must be provided with a slip-resistant surface
The distance a plank projects beyond its end support: not less than 50 millimetres and not exceeding 4 times the thickness of the plank, unless effectively prevented from tipping or lifting
When procuring steel grating in the Singapore market, you must ensure that the product’s load capacity meets this statutory requirement. When selecting, you should request a load calculation sheet corresponding to the type from the supplier to confirm whether the 670 kgf/m² requirement can be met under your project’s support spacing.
4.2 Singapore Steel Grating Standard SS 363:2014
Singapore National Standard SS 363:2014 “Specification for steel gratings for roads, drains and walkways” covers the technical requirements for steel gratings used in roads, drains and walkways, including:
Load classes for road gratings and frames (B125, C250, D400, E600, etc.)
Geometric dimension tolerances for steel gratings
Hot-dip galvanized surface treatment requirements
Basic requirements for slip resistance performance
This standard also covers steel grating requirements for depressed inlets. For steel grating procurement in the Singapore market, in addition to meeting type parameters, you must also confirm that the product complies with the requirements of SS 363.
4.3 Load Classes and EN 124 Standard
The load classes for steel grating are mainly classified according to the European standard EN 124:
| Load Class | Test Load | Typical Application Scenarios |
|---|---|---|
| B125 | 125 kN | Sidewalks, green areas, cycle tracks |
| C250 | 250 kN | Footpaths, cycle tracks, private driveways |
| D400 | 400 kN | Carriageways, parking lots, general traffic roads |
| E600 | 600 kN | Port terminals, logistics centres, heavy load areas |
When selecting drainage channel covers, please choose the appropriate load class according to the road grade of your project.
Chapter 5: Q&A: Common Questions on Steel Grating Selection
Q1: What do "S" and "F" represent in the type designation? When do I need to choose a type with "S"?
A: “S” represents serrated bearing bars, with serrated teeth approximately 2-3mm high on the surface, providing slip resistance. “F” represents flat bearing bars, with a smooth surface. Regulation 11(2) of Singapore’s Factories Regulations explicitly requires that metal plates forming a working platform must have a slip-resistant surface. Therefore, for steel grating used on working platforms in Singapore, it is strongly recommended to choose the serrated type with “S”. For ramps, wet or oily areas, the serrated type with “S” is a must.
Q2: What is the difference between pressure-welded (W) and press-locked (L) steel grating?
A: Pressure-welded steel grating fixes cross bars to bearing bars by pressure resistance welding, offering high production efficiency and good quality consistency. It is the most common type on the market. Press-locked steel grating fixes cross bars by pressing them into slots cut in the bearing bars, providing a more aesthetically pleasing appearance. Both transverse and longitudinal directions are load-bearing, but the cost is higher. In the type designation, W (pressure-welded) is usually omitted, while L (press-locked) must be explicitly marked.
Q3: What is the difference between 30mm and 40mm bar spacing?
A: A bar spacing of 30mm gives a denser grid, stronger prevention of small object falls, and is suitable for crowded walkways or areas with fall prevention requirements. A bar spacing of 40mm gives higher water permeability and better drainage efficiency, making it suitable for drainage channel covers or outdoor platforms. Series 1 (spacing 30mm) is the most widely used type, offering the strongest resistance to surface impact.
Q4: Why is hot-dip galvanizing (G) often omitted in the type designation?
A: According to YB/T 4001.1, hot-dip galvanizing is the most common surface treatment, so the “G” can be omitted in the type designation. If no surface treatment mark is seen in the type, hot-dip galvanizing is the default. Painted (P) or untreated (U) must be explicitly marked. The thickness of the hot-dip galvanized coating should comply with GB/T 13912-2020: general environment ≥65μm, medium corrosive environment ≥85μm, severe corrosive environment ≥100μm. Singapore has a tropical maritime climate with high salt spray and high humidity, so it is recommended to choose a product with coating thickness ≥100μm.
Q5: How can I determine whether the load capacity of steel grating meets the requirements of Singapore's Factories Regulations?
A: Singapore’s Factories Regulations require that planks sustain a load of 670 kgf/m² having regard to support spacing. The determination method is as follows:
Confirm whether the bar dimensions of the selected type meet the project’s load requirements (greater bar height and thickness give higher load capacity)
Confirm that the support spacing does not exceed the allowable span for that type (different specifications have different allowable spans)
Request a load table or third-party load test report from the supplier to verify whether the 670 kgf/m² requirement can be met under your support spacing
For heavy load areas (e.g., forklift aisles), it is recommended to engage a structural engineer for load verification calculations.
Q6: How is galvanized coating thickness tested? What are the acceptance criteria?
A: Coating thickness should be tested non-destructively using a magnetic thickness gauge, measuring at least 5 points per 10 square metres. According to GB/T 13912-2020, when the workpiece thickness is ≥6mm, the average coating thickness shall be greater than 85μm, and the local thickness shall be greater than 70μm. For high-corrosion environments such as Singapore, it is recommended to raise the requirement to average thickness ≥100μm. During acceptance, check whether the coating is uniform and free from uncoated areas, flaking, or peeling.
Chapter 6: Quick Selection Table for Steel Grating (Applicable to Singapore Market)
| Selection Scenario | Recommended Type | Bar Size | Bar Spacing | Cross Bar Spacing | Slip Resistance Form | Coating Requirement | Application Notes |
|---|---|---|---|---|---|---|---|
| Indoor walkway | G323/30/100 | 32×3mm | 30mm | 100mm | Flat/Serrated | ≥85μm | Light duty, personnel access |
| General industrial platform | G325/30/100S | 32×5mm | 30mm | 100mm | Serrated | ≥100μm | Medium load, meets 670 kgf/m² |
| Outdoor wet platform | G325/30/100S | 32×5mm | 30mm | 100mm | Serrated | ≥100μm | High slip resistance during rainy season |
| Equipment maintenance platform | G405/40/150S | 40×5mm | 40mm | 150mm | Serrated | ≥100μm | Heavy load, equipment-intensive area |
| Drainage channel cover | G325/30/100S | 32×5mm | 30mm | 100mm | Serrated | ≥100μm | B125/C250 load classes |
| Forklift aisle | G505/40/150S | 50×5mm | 40mm | 150mm | Serrated | ≥100μm | Dynamic heavy load, D400/E600 |
| Coastal / high salt spray area | G405/40/150S | 40×5mm | 40mm | 150mm | Serrated | 316L SS | Marine-grade corrosion protection |
Chapter 7: Conclusion and bangtu Company's Technical Commitment
The type designation of steel grating is not mysterious – it is a standardised technical language that records key information such as bearing bar dimensions, grid spacing, manufacturing process, bar profile, and surface treatment. Understanding this coding enables you to accurately select products that meet your engineering requirements, avoiding procurement errors, project delays, and safety risks caused by misinterpretation of type designations.
When procuring steel grating in the Singapore market, in addition to understanding the type parameters, special attention should be paid to:
Load compliance: Ensure the product meets the statutory load requirement of 670 kgf/m² under Singapore’s Factories Regulations
Slip resistance requirement: Metal plates for working platforms must have a slip-resistant surface; it is recommended to choose “S” serrated products
Corrosion protection level: Singapore has a tropical maritime climate; it is recommended to choose galvanized coating ≥100μm or 316L stainless steel
Standard compliance: Confirm that the product meets SS 363:2014 and EN 124 load class requirements
Quick selection advice for buyers:
First determine the application scenario (indoor/outdoor, personnel/equipment, load magnitude)
Then determine bar dimensions (bar height 30mm-50mm, thickness 3mm-5mm)
Select bar spacing (30mm for fall prevention, 40mm for high water permeability)
Confirm slip resistance requirement (choose “S” if required)
Confirm corrosion protection requirement (choose hot-dip galvanized ≥100μm for general environments, 316L for coastal)
Provide the complete type designation to the supplier, e.g.: G325/30/100S (32×5mm bar, spacing 30×100mm, serrated, hot-dip galvanized)
About bangtu Company
Bangtu Company has specialized in the steel grating field for over two decades. Our products are widely used in industrial platforms, petrochemical facilities, marine engineering, and municipal infrastructure in Singapore and globally. We commit to:
All product lines comply with YB/T 4001.1-2019, providing clear type interpretation and technical parameter descriptions
All products meet the load requirements of Singapore’s Factories Regulations, with load capacity ≥670 kgf/m², and third-party load test reports available
Serrated slip-resistant steel grating is standard with “S” type, meeting the mandatory requirement for slip-resistant surfaces on metal plates under Singapore’s Factories Regulations
Hot-dip galvanized coating thickness ≥100μm, meeting corrosion protection requirements for Singapore’s high salt spray, high humidity environment
Providing full-process technical support from type interpretation to selection calculation, assisting buyers in placing accurate orders
Offering bilingual (Chinese/English) technical specifications and load calculation sheets to meet Singapore project tender requirements
Whether you are an engineer, procurement specialist, or project manager, if you still have questions about steel grating type designations, please feel free to contact us. We will help you accurately understand the meaning of each type designation and ensure you procure the correct product.
Tel/Whatsapp: +8613363180165
Email: james@bangtuwiremesh.com
Website: www.bangtusteelgrating.com | www.chinawiremesh.ru
Appendix: Referenced Standards and Literature
YB/T 4001.1-2019 “Steel Grating Bars and Matching Parts Part 1: Steel Grating Bars” , Ministry of Industry and Information Technology, Issued 27 August 2019, Implemented 1 January 2020
[Link: https://std.samr.gov.cn/hb/search/stdHBDetailedCNF?id=957D1F57029A8C7BE05397BE0A0A3C89]
Reference: Steel grating terminology, type designation rules, technical requirements, design for useSingapore Factories (Scaffolds) Regulations 2004 , Singapore Statutes Online, Published 14 January 2004
[Link: https://sso.agc.gov.sg//SL-Supp/S19-2004/Published?DocDate=20040114&ProvIds=pr11-]
*Reference: Regulation 11 – working platform load requirement 670 kgf/m², metal plate slip-resistant surface requirement, support projection ≥50mm and ≤4 times plank thickness*SS 363:2014 “Specification for steel gratings for roads, drains and walkways” , Enterprise Singapore, Published 2014
[Link: https://www.singaporestandardseshop.sg/Product/SSPdtDetail/bfc1c46b-9819-4ce9-98a2-24a3e3789dfd]
*Reference: Technical requirements for steel gratings for roads, drains and walkways, including load classes (B125, C250, D400, etc.), geometric dimension tolerances, hot-dip galvanized surface treatment requirements*EN 124 “Gully tops and manhole tops for vehicular and pedestrian areas – Design requirements, type testing, marking, quality control” , European Committee for Standardization
Reference: Load class classification B125, C250, D400, E600GB/T 13912-2020 “Metallic coatings — Hot dip galvanized coatings on fabricated iron and steel articles — Specifications and test methods” , State Administration for Market Regulation, Issued 2020
*Reference: Hot-dip galvanized coating thickness standards: general environment ≥65μm, medium corrosive environment ≥85μm, severe corrosive environment ≥100μm*YB/T 4001.1-2007 “Steel Grating Bars” , Issued 2007, superseded by 2019 edition
Reference: Basis for type designation system, predecessor to the 2019 standard
