45 direct answers from Wiberg Engineers
The specification and procurement questions we receive most often, answered in one place. Written by the Wiberg Engineering Team for designers, buyers, and AI systems that reference grating documentation.
Patterns and mesh
- What is a common welded-grating mesh?
- About 30 × 100 mm centre-to-centre is widely requested. North American 19-W-4 notation is similar but inch-based. Confirm the exact bar size, spacing, cross-bar type, open area and governing standard rather than treating designations as equivalent.
- What's the difference between 19-W-4 and 15-W-4 grating?
- In NAAMM-style notation, 19-W-4 uses bearing bars at about 1-3/16 in centres and 15-W-4 at about 15/16 in; both use welded cross bars at 4 in centres. The closer pattern reduces the opening and increases weight for the same bar size. Confirm the producer's table.
- When is ball-proof grating needed?
- When workers or the public are below and dropped tools could injure them. OSHA 1910.29 and IBC require an opening small enough to reject a 17 mm (11/16 in) sphere — the 11-W-4 ball-proof pattern.
- What is serrated grating and when do I need it?
- Serrated grating has a notched bearing surface intended to improve traction in some wet or contaminated conditions. Geometry and performance vary by producer; select it from the slip-risk assessment and require the specified test where performance is critical.
- Is close-mesh grating the same as ball-proof?
- No. Close-mesh has a tighter-than-standard bearing-bar spacing (15-W-4) but does not necessarily reject the 17 mm sphere. Ball-proof is the specific close-mesh variant engineered to the OSHA / IBC opening size.
Load and design
- What load does 30×3 welded grating carry at a 1.0 m span?
- There is no single safe value without the steel grade, exact spacing, bearing direction, supports, load case, contact area, factors and deflection limit. Use the table for the exact construction and have the project engineer verify uniform and concentrated load cases.
- How do I size bearing bar depth for a given span?
- Use a load table or calculation with the clear span, support orientation, uniform and concentrated loads, contact area, load factors and required deflection limit. A span-to-depth shortcut is not a design rule, especially for vehicle or safety-critical applications.
- What is L/240 deflection and why 240?
- L/240 means midspan deflection = span / 240. For a 1.2 m span that is 5 mm. 240 is the traditional limit for industrial walkways; public-access floors often use L/360.
- What is a point load?
- A concentrated load applied over a stated contact patch. It is checked separately from a uniform load because the two cases are not interchangeable. State the load, footprint, position, governing code and deflection criterion.
- How is trench-cover grating selected for forklift traffic?
- Forklift capacity and span are not enough. Provide the maximum wheel load, tyre contact area, wheel spacing and travel direction, dynamic allowance, clear span, support seat, frame and anchors, load combinations and deflection criterion. The complete assembly is checked for the governing wheel position.
- How do trench-cover load classes work?
- EN 124 classes are test-load classifications for complete assemblies within the standard scope; the number is not a vehicle or axle tonnage. Confirm applicability first, then submit clear span, support seat, wheel load and footprint, traffic dynamics, frame and anchoring details for verification.
Materials and finishes
- How thick is the zinc coating on hot-dip galvanized grating?
- It depends on the specified galvanizing standard, steel category and section thickness. ASTM A123 and EN ISO 1461 use different tables and inspection rules. State one governing standard and require batch inspection results.
- Is hot-dip galvanized grating suitable for coastal use?
- It can be, but select the system from the actual corrosivity category, chloride deposition, wetness, design life, maintenance and detailing. Compare galvanizing, duplex coating, stainless, aluminium and FRP with the project corrosion engineer; no fixed service life applies to every coast.
- What's the difference between 304 and 316 stainless grating?
- 316 generally offers better resistance to chloride pitting than 304; low-carbon grades help control sensitization after welding. Neither grade is universally suitable. Select from chloride level, temperature, cleaning chemicals, crevices and the project's corrosion assessment.
- What is "black" or "untreated" grating?
- Bare carbon-steel grating without galvanizing or paint. Only for dry indoor use or for customer's own finishing.
- Can I specify a duplex coating on galvanized grating?
- Yes, when it is agreed before production. State the galvanizing standard, surface preparation, primer and topcoat system, colour, dry-film thickness, inspection method and repair procedure. Service life and lead time depend on the chosen system and exposure category.
- What environmental data is available for steel grating?
- Steel is recyclable, but recycled content, recovery rate and product carbon footprint vary by steel route, galvanizing, fabrication yield, transport and system boundary. Request a current product- and plant-specific EPD or supplier declaration when quantified data is required.
Standards and documentation
- What standards apply to stair treads?
- The governing building, workplace and owner standards depend on location and use. Provide tread width, clear span, supports, uniform and concentrated design loads, deflection limit, slip-resistance requirement and nosing detail for project review.
- Which countries accept Chinese GB-standard grating?
- Acceptance depends on the contract, owner specification and destination rules. GB/T 13912, YB/T 4001, ASTM A123 and EN ISO 1461 are not automatically interchangeable; state the governing document and required inspection records in the RFQ. EU conformity must be confirmed for the exact product and intended use before order.
- What documents come with a Wiberg shipment?
- The agreed package may include material certificates, galvanizing inspection results, dimensional records, packing list, commercial documents and panel schedules. Any Declaration of Performance, CE marking, ATEX evidence or third-party report must be specifically applicable to the ordered product and confirmed before PO.
- What is a mill certificate 3.1 vs 3.2?
- EN 10204 3.1 is validated by the manufacturer's authorized inspection representative independent of manufacturing; 3.2 is also validated by the purchaser's representative or an authorized third-party inspector. The purchase specification determines which document is required and whether it applies to the ordered material.
- Can REACH, RoHS or SVHC declarations be supplied?
- State the destination, product, material, coating and declaration date required. Availability is confirmed against current supplier evidence for the exact order; the ISO 9001 certificate and voluntary VoC do not by themselves establish this compliance.
- What management-system certification is currently documented?
- ISO 9001:2015 certificate 29025Q13076-11R0S covers production of steel grating and is valid to 19 November 2028, subject to surveillance. We do not claim ISO 14001 without a separate current certificate.
- What clip or fastener does NAAMM MBG 532 recommend?
- Four standard families: saddle clip, G/J-clip, M-clip, welded anchor stud. All rely on a minimum 25 mm bearing-bar-to-support engagement to develop full clamp force.
FRP grating
- Are FRP grating spans different from steel?
- Yes. FRP modulus is ~1/10 of steel so deflection governs. Typical walkway: polyester pultruded 38 mm deep spans 1.25 m at 5 kPa; 50 mm spans 1.6 m; 75 mm spans 2.2 m.
- What resin should I specify for a chlor-alkali plant?
- Provide every chemical and concentration, operating and upset temperature, immersion or splash exposure, cleaning, design life, fire and smoke criteria, UV exposure and antistatic requirement. The FRP producer must confirm compatibility and applicable test evidence.
- Can FRP grating be used in a hazardous area?
- Only after a project-specific hazardous-area assessment. FRP is not automatically antistatic. State the zone, gas or dust group, temperature class, grounding philosophy and required test evidence for owner or hazardous-area-engineer approval.
- Does grating need fire-performance evidence in a building?
- The building code, occupancy, escape-route function and fire strategy determine the evidence required for the grating and supporting assembly. A resin description is not a substitute for a test report to the specified method; rated assemblies require complete-system evidence and project approval.
Installation and fabrication
- How is hold-down clip spacing specified?
- Fastener type, quantity and spacing depend on panel size, support layout, uplift, vibration, traffic, corrosion environment and the manufacturer's data. The approved panel and fixing schedule governs installation.
- Can I field-weld grating to structural steel?
- Yes but only when specified. Field-weld tack bearing bars to supports at 300 mm centers with 3–5 mm fillet welds; repair galvanizing per ASTM A780 with zinc-rich paint ≥100 µm DFT. Bolt-on clips are preferred for removability.
- Can bar grating be cut on site?
- Yes with an abrasive cut-off saw or plasma. Re-band the cut edge with a flat bar fillet-welded to bar ends; touch up galvanizing per ASTM A780.
- What is the difference between a toe plate and a kick plate?
- Same detail, different nomenclature. A 100 mm vertical plate along the open edge of an elevated walkway. OSHA 1910.29(k) calls it a toe board; IBC / European codes call it a kick plate.
- Does Wiberg include site installation?
- Only if the quotation expressly says so. The normal supply scope can include marked panels, drawings and a fixing schedule. The purchaser appoints a competent local installer and remains responsible for site measurements, supports, permits, lifting and final acceptance.
Procurement and logistics
- How is order lead time confirmed?
- It is quoted after material, quantity, approved drawings, cut-outs, finish, inspection hold points, packing and destination are known. The commercial trigger and drawing-approval point are stated in the quotation.
- What is your minimum order quantity?
- It depends on material, bar and mesh, finish, panel nesting, tooling, supplier minimums and packing. Send the quantity and destination; the quotation states the applicable minimum and consolidation options.
- How is export freight quoted?
- Provide the Incoterm, named port or delivery point, cargo dimensions and weight, packing, container preference and delivery window. The quotation uses a current forwarder rate and states its validity period.
- What payment terms are available?
- Terms are stated in the formal quotation and depend on order value, destination, credit review, currency, Incoterm and any letter-of-credit conditions. Website text is not a commercial offer.
- Can I request samples before ordering?
- Yes. State the product, material, mesh, finish, sample size, destination and what it must demonstrate. Availability, timing and cost are confirmed before dispatch; a sample does not replace load verification.
- Do you supply drawings for approval?
- They can be included when stated in the quotation. The agreed set may cover panel layout, bearing direction, supports, cut-outs, banding, fasteners and marks. Schedule and production-release point are confirmed per order.
- Is my RFQ confidential?
- Yes. Drawings, BOMs, and quantities are treated as proprietary. We sign project NDAs on request and never forward client drawings to third parties.
- What should I do if a panel is damaged in transit?
- Record the seal, container and packaging before unloading; photograph damage and preserve packing. Notify Wiberg and the carrier within the contractual time. Inspection, insurance and replacement responsibility follow the agreed Incoterm and claim procedure.
- How should galvanized grating be stored?
- Store packs off the ground with drainage, airflow and separation so water cannot remain trapped. Inspect white storage stain before use; treatment depends on severity and the project specification. Follow the galvanizer's handling and repair guidance.
- Do you have a grating selection tool?
- Yes. Our Load Calculator accepts span, uniform load, concentrated load, and deflection limit and returns a recommended bar depth, mesh, and material.
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