Specification
| Material | GX40CrSi28,GX130CrSi29,or other heat-resistant steel grades requested by the customer |
| Casting Dimensional Accuracy | CT9–CT11 |
| Process | Shell mold casting; Lost Foam Casting; Investment Casting, optional machining |
Why Can Boiler Grate Bars Made from the Same Alloy Have Different Service Lives?
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A boiler grate bar's service life depends on more than its alloy grade. Local metal temperature, thermal cycling, ash chemistry, and abrasive contact may combine to cause oxidation, hot corrosion, cracking, or permanent deformation.
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An ASM International case history reported that ASTM A297 Grade HH grate bars experienced a reduction in service life from more than seven years to approximately nine months after a change in production conditions. Alkali sulfate and chloride deposits were identified as the primary causes, with thermal cycling and abrasion contributing to the damage.[1]
Although this case involved a travelling-grate indurator rather than an industrial boiler, it demonstrates an important material-selection principle: a heat-resistant alloy grade cannot by itself offset an aggressive operating environment.
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Research on a 15 t/h biomass boiler supports the same conclusion. A 2024 CRFD study of a 15 t/h eucalyptus wood-chip boiler mapped non-uniform grate temperatures and identified regions susceptible to thermomechanical fatigue and metal-dusting corrosion. The findings show why local temperature distribution and gas chemistry should be reviewed together with the nominal alloy grade.[2]
For replacement selection, buyers should therefore evaluate the material grade together with fuel and ash properties, temperature distribution, cooling conditions, and previous service life.
What are Grate Bars Used for?
Grate Bars are widely used in boilers, waste incinerators, biomass boilers, and cement & industrial furnaces, providing reliable fuel support, efficient combustion, and long-lasting performance.
Boiler
Waste Incinerator
Biomass Boiler
Cement & Industrial Furnace
Request a Quote for Grate Bars
To help us provide an accurate quotation, please share the following information: Drawing or sample photos, Material requirement, Quantity.
Which Service Conditions Should Control Grate Bar Material Selection?
GX40CrSi28, GX130CrSi29 and other heat-resistant grades should be evaluated against the dominant failure mechanism-not simply ranked by chromium content or nominal temperature resistance.
A 2026 industrial study examined GX130CrSi29 grate bars removed from a 9.9 MW rubberwood-fired reciprocating-grate furnace. The research connected premature degradation with the combined effects of temperature, fuel and ash chemistry, oxidation and corrosion, demonstrating that even a recognized heat-resistant grade may deteriorate early when exposed to unfavorable service conditions.[3]
Before specifying a grate bar for boiler service, the following information should be reviewed:
Fuel type, lower heating value and moisture;
Ash content and ash-fusion behavior;
Chlorine, sulfur and alkali content;
Normal and maximum operating temperature;
Air- or water-cooling conditions;
Startup and shutdown frequency;
Existing material and previous service life;
Failure location and photographs.
ASTM A297/A297M describes its heat-resistant casting grades as general-purpose alloys and does not present them as universal solutions for every special high-temperature application.[4] Material compliance is therefore necessary, but it does not by itself prove suitability for a specific boiler.
Why Must Replacement Boiler Grate Bars Preserve Fit and Airflow?
A replacement boiler grate bar must reproduce the functional geometry of the original component-not merely its overall length and width. Mounting interfaces, support surfaces, grate pitch, air-slot geometry, side clearance and thermal-expansion allowance influence both mechanical movement and primary-air distribution.
Detroit Stoker and Babcock identify grate bars, grate chains and support rails as connected wear components. Their inspection criteria include fit and function, wear limits, physical distortion and high-temperature corrosion, followed by cold operational testing before startup.[5]
This is especially important when only part of an existing grate assembly is replaced. A new bar manufactured to the original drawing may still interact poorly with worn chains, distorted neighboring bars or damaged support rails.
For direct replacement, the following dimensions should be treated as critical:
Mounting hooks or connecting features;
Chain and support-rail contact surfaces;
Air-slot size, direction, and open area;
Grate pitch and cumulative row width;
Side clearance and thermal-expansion space;
Moving or stationary installation position.
A used sample should also be checked for wear and distortion before it is accepted as the dimensional reference. Direct replacement means verified functional interchangeability-not visual similarity to the failed component.
Why choose us
As an experienced grate bar manufacturer and grate bar factory, Welong delivers high-quality heat-resistant grate bars with strict quality control, custom manufacturing capabilities, and reliable global supply. Backed by 25+ years of manufacturing experience, we help customers achieve longer service life, stable performance, and lower lifecycle costs.
25+ Years of Manufacturing Experience
With over 25 years of manufacturing experience, we provide durable grate bars engineered for long service life, excellent heat resistance, and reliable performance in demanding combustion environments.
Superior Heat & Wear Resistance
Manufactured from high-quality heat-resistant materials, our grate bars offer excellent resistance to thermal fatigue, oxidation, and wear for reliable performance in demanding combustion environments.
Stricter Product Quality Control
Every grate bar undergoes strict quality control to ensure material consistency, dimensional accuracy, and stable performance, providing dependable quality from batch to batch.
Custom Manufacturing & Direct Replacement
We support custom production based on drawings or samples, manufactured to the confirmed drawing and agreed interface requirements with existing grate systems, minimizing installation time.
Quick and Reliable Customer Support
Our experienced engineering and service teams provide fast technical consultation, responsive communication, and professional support throughout the entire project lifecycle.
Lower Lifecycle Cost
By combining optimized designs, long service life, and reliable quality, our grate bars help improve combustion efficiency while reducing downtime and the total cost of ownership.
What Evidence Should Be Reviewed Before Shipment?
A chemical composition report verifies alloy chemistry, but it does not by itself confirm casting integrity, dimensional fit, or application suitability.
ASTM A781/A781M, which provides common requirements for industrial steel and alloy castings including ASTM A297 materials, addresses heat and product analysis, mechanical requirements, and casting surface condition. It states that castings must be free from unacceptable cracks, hot tears, adhering sand, scale, and other surface discontinuities.[6]
For boiler grate bar acceptance, the purchase specification should separately define:
Material grade and governing standard;
Critical dimensions and allowable tolerances;
Surface-condition requirements;
Heat or batch identification;
Chemical composition report;
Dimensional inspection report;
Any additional inspection required by the drawing;
Approval requirements for repair welding, if applicable.
For Welong grate bars, the current quality-control scope already includes spectrometric chemical analysis, dimensional inspection documents, and optional heat or batch number marking. Any additional hardness, metallographic, or nondestructive testing should be confirmed before quotation rather than assumed after production.
Quality Control
Process Control
Spectrometric chemical composition analysis of test bars cast together with each furnace batch. (Pre-Pouring Inspection, Pouring Process Monitoring, and Post-Pouring Inspection)
Finished Product Inspection
Spectrometric chemical composition analysis of sampled finished castings.
Traceability
Cast-in heat number/batch number marking available upon customer request for full material and production traceability.
Inspection Documents
Dimensional Inspection Report, Chemical Composition Report, and EN 10204 Type 3.1 Material Inspection Certificate (3.1B).
Our Cases
Our Factory
Certifications
ISO 9001:2015
ISO 9001:2015
Certificate name
Certificate name
Certificate name
Certificate name
References
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- [1] Mohanty, B. P., and Shores, D. A. (1992). "Hot Corrosion of Stainless Steel Grate Bars in Taconite Indurators." Handbook of Case Histories in Failure Analysis, Vol. 1, ASM International, pp. 358–362. https://doi.org/10.31399/asm.fach.v01.c9001109
- [2] de Sousa, M. A., Cancino, L. R., Deschamps, I. S., and Bazzo, E. (2024). "CRFD Modeling of High-Temperature Reciprocating Grate Degradation in a 15 t/h Eucalyptus Wood Chip Boiler." Renewable Energy, Vol. 230, Article 120858. https://doi.org/10.1016/j.renene.2024.120858
- [3] "Failure Analysis and Degradation Mechanisms of GX130CrSi29 Grate Bars in a Biomass-Fired Furnace: An Industrial Case Study," ScienceDirect, 2026. https://www.sciencedirect.com/science/article/pii/S2214157X26003758
- [4] ASTM A297/A297M, "Standard Specification for Steel Castings, Iron-Chromium and Iron-Chromium-Nickel, Heat Resistant, for General Application," ASTM International, West Conshohocken, PA. https://www.astm.org/a0297_a0297m-21a.html
- [5] Morrow, R. S., and Wannenburg, E. (2026). "Improved Annual Outage Execution to Extend Boiler Grate Service Life." Technical conference paper presented at the South African Sugar Technologists' Congress, Durban, South Africa, August 20, 2026. Detroit Stoker Company and Babcock Ntuthuko Engineering. Public abstract published by Detroit Stoker Company on August 28, 2026. View the public technical abstract
- [6] ASTM A781/A781M, "Standard Specification for Castings, Steel and Alloy, Common Requirements, for General Industrial Use," ASTM International, West Conshohocken, PA. https://www.astm.org/a0781_a0781m-21.html
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