Quick answer: UNS N08811 identifies Incoloy 800HT, but “seamless shell taper fitting” is not a complete order description. A reliable RFQ should state the component drawing, material/product standard, fitting or forging route, dimensions and tolerances, construction, solution-heat-treated condition, surface, examination, pressure-code requirements and certification.
Incoloy 800HT is the controlled-composition, solution-treated member of the 800 alloy family used where elevated-temperature creep and stress-rupture properties are relevant. Review the Incoloy 800HT product page, then use the checks below to define a taper fitting without relying on a photograph or informal name.
Material Identity and Product Form Are Separate
| Item | What it defines | What still must be specified |
|---|---|---|
| UNS N08811 / 800HT | Alloy identity with controlled chemistry and heat-treatment requirements | Product form, geometry, dimensions, testing and code |
| ASTM B366/B366M | Factory-made wrought nickel-alloy fittings within its scope | Applicable grade/class, dimensional standard and order options |
| ASTM B564 | Nickel-alloy forgings within its scope, including N08811 | Whether the component is ordered as a forging, flange or machined part |
| Drawing or dimensional standard | Taper, ends, wall, bore, angle, length and tolerances | Revision, inspection points and any special machining |
Why 800HT Condition Matters
The 800HT designation is not created by chemistry alone. Published manufacturer information distinguishes 800HT by restricted carbon and aluminum-plus-titanium controls within the 800H family, together with a high-temperature solution treatment. The purchase order should therefore require the applicable UNS grade and the governing product specification rather than accepting a generic “800 series” statement.
For pressure or furnace service, the material condition must also match the design code and temperature range. A component manufacturer should not infer allowable pressure or service temperature from the alloy name; those values depend on code edition, product form, dimensions, joint design and design calculations.
Taper Fitting Geometry to Put on the Drawing
| Geometry field | Buyer should state |
|---|---|
| End type | Butt-weld, socket-weld, threaded, plain, machined or project-specific end |
| Taper | Included angle or slope, large and small diameters, bore transition and straight lengths |
| Wall and schedule | Nominal wall, minimum wall and any matching-pipe schedule where applicable |
| Overall dimensions | Length, centerline dimensions, machining allowance and datum scheme |
| Tolerances | Dimensional standard or drawing-specific limits, including ovality and alignment |
| Surface | As-forged, machined, pickled, cleaned or drawing-defined condition, with permitted imperfections |
Inspection and Documentation
- Material certificate tied to heat/lot traceability and the ordered standard.
- Chemical composition and heat-treatment condition for UNS N08811.
- Dimensional report against the approved drawing and revision.
- Visual and surface examination with agreed acceptance criteria.
- PMI, penetrant, radiography, ultrasonic examination or hydrostatic testing only when the order defines method, extent and acceptance.
- Marking, packing and documentation requirements appropriate to the project.
Copy-Ready RFQ Structure
UNS N08811 Incoloy 800HT taper fitting; governing material standard and revision; applicable fitting/forging and dimensional standard; seamless, welded, forged or machined construction as required; drawing number and revision; end type; large/small diameter; wall; angle; length; tolerances; heat-treatment condition; surface; quantity; inspection methods and acceptance; material certificate; packing; destination.
Frequently Asked Questions
Are Incoloy 800H and 800HT interchangeable? Not automatically. 800HT applies additional chemistry controls within the 800H family and a defined high-temperature solution treatment. Use the exact UNS grade and project-approved specification.
Does “seamless” mean the fitting is forged? Not by itself. Seamless describes the absence of a weld seam; forged, wrought, machined and formed describe manufacturing routes. The order should define the required route and governing product standard.
Conclusion
A taper fitting is defined by both material and geometry. UNS N08811 confirms the 800HT alloy identity, while the selected product standard, drawing, construction route, heat treatment, dimensions and inspection determine what is actually supplied. Keeping those fields separate prevents a material name from becoming an incomplete component specification.
Send a Complete Enquiry
Send the drawing, material and dimensional standards, UNS grade, construction route, dimensions, condition, quantity and inspection requirements. SASA Alloy will review the requested fitting scope.
Post time: Dec-26-2018