GNEE has finished manufacturing and delivery of custom Incoloy 800H U bend tubes for a heat exchanger project. This batch includes 255 units, fabricated strictly according to the client's full set of engineering drawings under ASTM B407 specification. This order adopts a dissimilar wall thickness butt-welded structure, a custom design many alloy fabricators are reluctant to undertake.
Project Core Specifications：
| Parameter | Specification |
|---|---|
| Material Grade | Incoloy 800H, UNS N08810 |
| Applicable Standard | ASTM B407 |
| Outer Diameter | 48.26 mm |
| Wall Thickness (Side 1) | 5.08 mm, SCH80 |
| Wall Thickness (Side 2) | 3.68 mm, SCH40 |
| End Machined Bevel | 37.5° |
| Bend Radius | 228.6 mm |
| Total Quantity | 255 pcs |
All finished tubes maintain a uniform outer diameter of 48.26 mm. The SCH80 heavy-wall section is designed for high-pressure operating zones. The SCH40 thinner wall section improves overall heat transfer efficiency for the heat exchanger.
Both tube ends require precision machined 37.5° bevels. This bevel geometry matches the client's requirements for field tube-to-tube sheet welding. The full dimension tolerance rules are clearly defined within the submitted engineering drawing.
Material Introduction: Incoloy 800H ASTM B407 UNS N08810
Incoloy 800H (UNS N08810) is a nickel-iron-chromium alloy with controlled carbon content. The alloy delivers stable performance under long-term high-temperature service up to 815 ℃. It provides outstanding creep resistance and excellent resistance to carburization.
ASTM B407 is the standard specification for seamless ferritic nickel-chromium alloy tubes. This standard covers tubular products designed for high-temperature heat transfer and process equipment. It is widely adopted by heat exchanger and petrochemical engineering contractors.
Recognized Industry Difficulties of This Custom Design
The drawing below is the original engineering drawing provided by the client for this batch of Incoloy 800H U bend tubes. Key structural details including dissimilar wall sections, butt weld location, bend radius and 37.5° bevel tolerances can be directly identified from the drawing. These special geometric requirements create three major technical challenges, which make many alloy manufacturers hesitate to accept this project.
1.Dissimilar wall butt welding The two pipe segments have a 1.4 mm wall thickness difference while sharing identical outer diameter. Mismatched wall cross-sections raise risks of welding distortion and localized stress concentration.
2.Post-welding cold bending control Many manufacturers decline this type of design due to high rejection risk after bending. Incoloy 800H nickel-iron-chromium alloy shows obvious springback during cold forming. The welded joint must remain intact after U-bending without cracking or excessive ovality.
3.High-precision bevel machining The third technical hurdle is tight-tolerance bevel machining. Each tube end must reach the 37.5° bevel angle within controlled tolerance. Minor deviation will interfere with assembly and welding quality on the heat exchanger site.
Free Inconel 800H Consultation
If your heat exchanger project needs dissimilar wall U bend tubes to balance pressure resistance and heat transfer, our engineering team can complete full manufacturability review based on your drawings.
GNEE Technical Preparation After Receiving This Order
Our metallurgical and welding engineers started drawing decomposition and tolerance verification immediately after order confirmation. We marked every dimension limit, bevel requirement and bend allowance before raw material sourcing. All ambiguous tolerance points were clarified with the client in advance to avoid production deviation.
We sourced seamless Incoloy 800H pipe that fully complies with ASTM B407 requirements. Every incoming pipe lot underwent PMI positive material identification to confirm UNS N08810 composition. Raw material test certificates were collected and filed for traceability.
A dedicated Welding Procedure Specification (WPS) was developed for this dissimilar wall butt joint. We finished welding qualification tests before mass production launch. The qualification verified joint integrity even after subsequent U-bend forming.
Small sample bending trials were arranged to adjust springback compensation values. Trial pieces helped us lock the CNC bending parameters to control tube ovality. We also drafted a full inspection checklist covering all drawing-specified test items.
Production Execution and Full-Lot Inspection
Raw SCH40 and SCH80 Incoloy 800H pipes were cut to the drawing-defined lengths. Certified welders carried out butt welding following the pre-approved WPS. Each weld seam passed ultrasonic non-destructive testing before bending.
Qualified welded workpieces were sent to the CNC bending machine for U-shape forming. After bending, both tube ends were processed on machining centers for 37.5° bevels. Dimensional checks were implemented for length, outer diameter, wall thickness and bevel angle.
All 255 pieces passed the complete inspection scope listed in the client drawing. Visual surface inspection, PMI recheck and hardness testing were performed for final confirmation. Qualified products were packed for shipment to the heat exchanger manufacturer.
GNEE supports custom Incoloy 800H U bend tube orders with special welding, bending or bevel specifications. You may submit your engineering drawings for professional technical assessment and solution planning.
Typical Application of GNEE Incoloy 800H U Bend Tubes
- Shell-and-tube heat exchangers and steam generators
- High-temperature heat recovery equipment
- Cooling systems for petrochemical reactors
- Process units with mismatched pressure and thermal loads, where dissimilar wall construction is required
Packaging & Shipment of Incoloy 800H U Bend Tubes
For high-precision and high-value nickel alloy U bend tubes, GNEE adopts customized anti-collision and anti-corrosion packaging solutions suitable for long-distance ocean transportation.
1.All tube surfaces are manually cleaned and inspected to remove machining oil, dust and metal residues. Each finished Incoloy 800H tube is individually wrapped with anti-rust paper and plastic film to avoid surface oxidation and scratch marks.
2.Special fixed foam brackets are used for U-shaped bending sections. Different from straight tubes, U bend products are prone to extrusion deformation during stacking and transportation. Custom foam positioning effectively protects the bend radius and avoids ovality distortion.
3.All tubes are sorted by size and quantity, bundled and fixed with plastic straps, and placed in thick export wooden boxes. Reinforced corner protection is added to the wooden boxes to prevent extrusion and collision during container loading and transit.
4.Each box is marked with clear labels including material grade, standard, quantity, dimension and batch number. Complete packing lists and material certificates are attached for customs clearance and customer receiving inspection.
GNEE's standardized export packaging ensures zero surface damage, zero deformation and stable quality for delivered Incoloy 800H U bend tubes after long-distance shipping.
GNEE's Broader Capabilities for Challenging Nickel Alloy Orders
This successful delivery is not an isolated case. GNEE is equipped to evaluate and produce nickel alloy tubular products with non-standard geometries, strict tolerance rules and complex welding requirements.
We keep expanding our manufacturing and inspection capacity for challenging heat exchanger tube projects. We welcome custom drawing-based orders for Incoloy, Inconel and Hastelloy alloy tubular components from global EPC and heat exchanger manufacturers.
