Bend Tube Shield
Bend Tube Shield - seamless steel tube
Non-hardenable SS430 ferritic stainless half round tube shields, excellent thermal stability & anti-stress-cracking performance for clean low-sulfur economizer tube bundles, full matching SS430 C/U snap ring fasteners.
430 stainless steel tube shields, also called SS430 U-type half round boiler sleeves, belong to ferritic stainless steel, a distinct category separate from martensitic SS410 and SS420 grades. Containing 16~18% chromium and zero nickel, SS430 features superior atmospheric oxidation resistance and excellent resistance to chloride stress corrosion cracking, a key advantage unavailable in martensitic 400-series materials.
This material is non-hardenable via heat treatment; instead of focusing on extreme hardness for heavy fly ash abrasion, it prioritizes long-term thermal stability and rust prevention for clean, low-sulfur combustion environments. Small industrial boilers, low-sulfur biomass boilers, clean natural gas-fired economizers and waste heat recovery units with dry flue gas are perfect matching scenarios. Even under frequent temperature cycling, SS430 maintains stable structure without rapid scaling or stress cracks, effectively isolating radiant heat and mild fly ash erosion to stop base tube thinning and burst failures.
We manufacture full structural series purely in SS430: straight half sleeves, inner U-bend wrap shields, outer bend full wrap sleeves and wave fin inter-tube baffles. All supporting C-type & U-type snap lock fasteners adopt identical SS430 ferritic stainless, eliminating dissimilar metal galvanic corrosion risk under long-term fluctuating boiler temperatures.
SS430 ferritic tube shields fill the material gap between low-cost martensitic SS410/420 and high-temperature austenitic 309S/310S, supporting three mature protection schemes classified by flue abrasion severity:
Integral hydraulic stamped 180° semicircular sleeve is our flagship SS430 product. Precision-matched radian fully fits standard ASME heat transfer tube outer diameters without gaps, avoiding trapped ash and localized concentrated abrasion. Dual installation options including snap ring clamping and spot welding enable flexible construction during annual boiler shutdown maintenance, widely selected for clean low-sulfur gas-fired boiler economizer renovation requiring stable anti-oxidation performance and controlled procurement budget.
For low-sulfur flues with continuous medium fly ash impact where single SS430 plate cannot reach expected service cycle, we supply composite shields combining SS430 outer shell and thin alumina ceramic lining. This design retains ferritic steel’s outstanding stress corrosion resistance while lifting overall wear resistance, ideal for light-load CFB and low-sulfur biomass boiler tail flue zones.
Thin SS430 plate acts as base carrier for high-temperature wear-resistant ceramic coating spraying, applied on densely packed compact tube bundles where standard half round sleeves cannot be mounted. It forms dual metal + coating composite protection layer to extend base heat transfer tube service life under clean flue conditions.
SS430 (UNS S43000 / EN 1.4016) is classic low-carbon ferritic stainless steel complying with ASTM A240 standard, its chemical composition and mechanical indicators optimized for clean boiler dry flue thermal protection components:
| Performance Item | Standard Parameter Value | Inspection & Test Standard |
|---|---|---|
| Carbon Content (C Max) | 0.12 % | ASTM A240 Spectral Composition Test |
| Chromium Content (Cr) | 16.0 ~ 18.0 % | ASTM A240 Spectral Composition Test |
| Tensile Strength (Annealed State Min) | ≥ 450 MPa | ASTM A370 Tensile Mechanical Test |
| Yield Strength (0.2% Offset Min) | ≥ 205 MPa | ASTM A370 Tensile Mechanical Test |
| Max Continuous Long-term Service Temperature | ≤ 815°C | High-temperature oxidation aging test |
| Max Intermittent Service Temperature | ≤ 870°C | Actual boiler flue application verification |
| Hardness (Annealed, HRB Max) | 89 HRB | Rockwell Hardness Test |
Material Selection Critical Reminder: SS430 tube shields only adapt to clean, low-sulfur, dry flue environments; not suitable for high-sulfur coal-fired boilers, chloride-containing waste incineration flues. For heavy sulfur or high chloride working conditions, select 309S / 310S austenitic stainless half round tube shields instead.
All SS430 erosion protective sleeves adopt integrated hydraulic stamping forming process, with strict incoming material inspection and surface finishing treatment to guarantee stable long-term anti-oxidation performance inside clean boiler flues:
Stock SS430 semicircular sleeves match mainstream ASME SA179, SA210, SA213 heat transfer tube outer diameters, non-standard arc radian and total sleeve length support dedicated mold customized development:
| Matched Base Tube Outer OD (mm) | SS430 Alloy Plate Thickness (mm) | Shield Total Length Range (mm) | Common Structural Form Type |
|---|---|---|---|
| 32 / 38 / 42 | 6 / 8 | 100 ~ 1200 | Straight half round single tube thermal protection sleeve |
| 51 / 57 / 60 | 8 / 10 | 150 ~ 1800 | Straight half wrap / wave fin inter-tube protective baffle |
| 76 / 89 | 10 / 12 | 200 ~ 2500 | Outer U-bend full wrap semicircular shield |
Note: Extra thick enhanced wear-resistant SS430 plate, super long customized sleeves and oversized large radian bend shields can be custom manufactured strictly according to customer boiler construction layout drawings.
Two mature installation schemes are provided to adapt different boiler overhaul construction cycles and flue fly ash abrasion intensity levels:
All supporting snap lock fasteners adopt pure SS430 ferritic stainless material consistent with tube shield body, effectively avoid electrochemical corrosion phenomenon generated by dissimilar metal contact under long-term temperature cycling flue gas environments.
| Supporting Product Name | Core Functional Description | Matching Application Working Scene |
|---|---|---|
| 430 Ferritic Stainless Half Round Tube Shield | Semicircular outer wall thermal & mild anti-scour wrap for single boiler heat transfer tube | Clean gas-fired economizer, low-temperature superheater straight tube bundle protection |
| SS430 C & U Snap Lock Fasteners | Non-weld quick locking clip matched for half round tube shields | Small & medium diameter tube bundles with frequent inspection requirements |
| SS430 Wave Fin Inter-tube Anti-wear Baffle | Ash impact buffer plate installed between adjacent finned heat exchange tubes | Low-sulfur clean flue water wall fin transition mild abrasion zones |
| SS430 Cast Alloy Saddle Pipe Clamp | Heavy-duty fixed support for full tube bundle assembly layout | Large-scale gas boiler economizer tube bundle overall fixed installation framework |
430 ferritic stainless steel tube shields are specially developed for clean, dry, low-sulfur flue heating surfaces with mild fly ash abrasion and stable high-temperature oxidation demand:
Application Limit Reminder: SS430 tube shields cannot be applied to high-sulfur coal combustion flues, chloride-containing waste incineration systems, or furnace arch zones over 870°C continuous operation; select 309S / 310S high-temperature austenitic half round shields for above harsh working conditions.
| Comparison Item | 410 Stainless Shield (Martensitic) | 420 Stainless Shield (Martensitic) | 430 Stainless Shield (Ferritic) | 309S Stainless Shield (Austenitic) |
|---|---|---|---|---|
| Max Continuous Service Temp | 550°C | 600°C | 815°C | 850°C |
| Hardenable By Heat Treatment | Yes | Yes | No | No |
| Stress Corrosion Cracking Resistance | Poor | Poor | Excellent | Medium |
| Medium Fly Ash Hard Abrasion Resistance | General | Excellent | General (For clean flue only) | Good (High temp only) |
| Sulfur Flue Corrosion Tolerance | Only ultra-low sulfur | Only ultra-low sulfur | Low sulfur clean flue only | Medium sulfur tolerance |
| Raw Material Procurement Cost Level | Lowest | Low | Medium-Low | Medium |
| Core Applicable Boiler Scenario | Light abrasion low temp economizer | Medium abrasion low temp economizer | Clean gas low-sulfur high temp economizer | Medium-high temp superheater high sulfur flue |
SS430 low-carbon ferritic stainless steel has dedicated welding operation requirements; following standardized construction rules can avoid grain coarsening and intergranular corrosion defects, extending tube shield overall service life:
1. Hoisting & transportation handling rule: Avoid violent knocking, extrusion and impact on SS430 shield plate surface during loading and installation, to prevent invisible stamping microcracks on semicircular arc body.
2. Welding operation mandatory specification: Preheat workpiece to 200 ~ 280°C before spot welding construction, adopt special ferritic stainless welding rod, implement slow air cooling treatment after welding to reduce intergranular corrosion risk.
3. Snap ring clamping installation inspection point: Ensure full seamless fitting between SS430 half round shield and heat transfer tube outer wall, symmetrically lock C/U snap rings on both sleeve ends to prevent shield sliding displacement under long-term flue gas vibration impact.
4. Annual boiler shutdown overhaul inspection item: Check SS430 plate wall oxidation scaling thickness and welding joint crack status, replace severely scaled and deformed shields in advance to prevent base heat transfer tube abrasion perforation leakage accidents.
5. Warehouse finished product storage protection: Stack SS430 tube shields with isolation paper between layers, seal warehouse space with dehumidification measures to avoid surface moisture rust before shipment delivery.
The structural shape and chemical alloy formula of our SS430 half round tube thermal shields are fully optimized targeting clean low-sulfur gas boiler high-temperature economizer flue working conditions:
1. One-piece integral hydraulic stamping semicircular U-shaped structure eliminates assembly splicing gaps, completely avoid ash accumulation and localized concentrated abrasion defects commonly seen in segmented tile-spliced protective covers.
2. 16~18Cr low-carbon nickel-free ferritic formula balances moderate raw material cost and outstanding high-temperature oxidation resistance, providing cost-effective thermal protection solution for clean fuel boiler tube bundle transformation projects requiring stable anti-stress-cracking performance.
3. Interchangeable multi-type structural variants (straight half wrap, fin inter-tube baffle, outer U-bend full cover) cover all mainstream clean flue heating surface layout designs, eliminating secondary on-site cutting and transformation work for most standard boiler tube bundles.
4. Uniform consistent alloy plate thickness design guarantees synchronous oxidation scaling speed across the whole SS430 shield surface, avoiding partial premature plate thinning under uneven mild fly ash particle impact distribution inside boiler flues.
We provide full customized SS430 half round tube shield manufacturing service strictly against customer boiler overhaul construction drawings, flue operating temperature and fly ash abrasion intensity technical parameters:
Customizable core technical parameters: Matched heat transfer tube outer diameter, SS430 alloy plate thickness, half round shield total length, semicircular arc radian, wave fin baffle height, outer U-bend wrap coverage angle.
Special customized optional solutions: Extra thick mild abrasion resistant SS430 alloy plate, oversized outer U-bend full wrap shield, pre-assembled integrated shield + snap ring assembly for fast on-site installation.
Attached professional technical supporting service: Clean low-sulfur boiler high-temperature flue thermal protection scheme consultation, on-site welding construction technical guidance, long-term bulk spare parts supply framework contract for gas boiler annual maintenance cycles.
430 ferritic stainless steel half round tube shields adopt layered isolation shockproof packaging design to protect stamped semicircular arc structure from extrusion deformation damage during cross-border sea and land long-distance transportation:
Small batch small-size SS430 shields separated by foam isolation paper and packed into fumigated export wooden cases; large quantity bulk finished products stacked on standard steel pallets, fixed with steel binding strips, whole pallet outer layer wrapped anti-rust stretch plastic film for moisture isolation.
Multiple international trade terms FOB / CFR / CIF are fully supported, sea freight and land highway transportation options available according to customer designated delivery port and delivery schedule time requirements.
Each shipment batch attached complete full set delivery documents: SS430 material spectral composition test report, dimensional inspection record, on-site installation operation manual, convenient for overseas gas boiler project customs clearance and equipment acceptance inspection work.
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When you partner with Sunny Steel, you can stop worrying about meeting deadlines thanks to our responsive and timely service. You'll also say goodbye to unnecessary shopping around. Instead, you'll get white glove service from an expert who understands your needs and can get you the materials you need quickly.
