Description
Traceable alloy butt-weld fitting
ASTM B366 Alloy 20 Custom Unequal Tee
A procurement-ready custom unequal butt-weld tee in ASTM B366/B366M, UNS N08020 iron-nickel-chromium-molybdenum-copper alloy, supplied for sulfuric-acid, chemical, fertilizer and pharmaceutical service with project-defined dimensions, wall, construction and inspection.
What is a Alloy 20 custom unequal tee?
A custom unequal tee is used when standard reducing-tee combinations do not match the required run, outlet, branch or center-to-end dimensions. Each end wall, transition and branch reinforcement must be reviewed against the approved design.
Alloy 20 is the common commercial name for UNS N08020. It is considered in sulfuric-acid processing, fertilizer, chemical and pharmaceutical systems where its corrosion performance is verified for the actual concentration and temperature.
Technical specification
| Product type | Custom unequal butt-weld tee |
|---|---|
| Material | ASTM B366/B366M, UNS N08020 iron-nickel-chromium-molybdenum-copper alloy |
| Material family | Iron-nickel-chromium-molybdenum-copper alloy |
| Dimensional basis | Approved project drawing; applicable B16.9 requirements by agreement |
| Configuration | Custom run/outlet/branch diameters and center-to-end dimensions per approved drawing |
| Nominal size | Run × outlet × branch dimensions reviewed individually for manufacturability |
| Wall thickness | Standard schedules, heavy wall and project-specific wall subject to manufacturing review |
| Construction | Formed or fabricated construction subject to material specification, code and approved drawing |
| End preparation | Butt-weld bevel matched to connecting pipe wall and approved welding detail |
| Heat treatment | Solution treatment and final condition as required by ASTM B366 and the ordered class |
| Documentation | EN 10204 3.1 MTC, heat traceability, PMI, dimensions and additional NDE as ordered |
Available size and wall combinations depend on alloy, forming route, construction and quantity. Confirm the exact pipe outside diameter and wall in the RFQ.
Standards and technical references
Dimensional standard
The approved project drawing controls non-standard unequal-tee geometry. ASME B16.9 applies only to requirements and configurations explicitly included in the order and within its scope.
Material specification
ASTM B366/B366M covers factory-made wrought nickel and nickel-alloy pressure-piping fittings.
Why select Alloy 20?
UNS N08020 is considered for sulfuric-acid handling, fertilizer production, chemical processing, pharmaceuticals and food-process equipment exposed to compatible corrosive media.
| Selection point | Alloy 20 | Hastelloy C276 |
|---|---|---|
| Alloy family | Fe-Ni-Cr-Mo-Cu | Ni-Mo-Cr severe-service alloy |
| Typical focus | Selected sulfuric-acid environments | Broader severe chemical corrosion |
| Relative cost | Often more economical when suitable | Typically higher |
| Selection | Verify acid concentration and temperature | Verify full process chemistry |
Typical applications
| Industry | Typical fitting duty | Why this material is considered |
|---|---|---|
| Chemical processing | Special three-diameter branch connection in process piping | Sulfuric-acid and compatible process systems |
| Fertilizer production | Large-bore header transition with a non-standard branch | Acid transfer and process equipment |
| Pharmaceutical and food | Replacement fitting matched to existing plant dimensions | Selected corrosive clean-process systems |
Application examples are selection context, not a design approval. Confirm process chemistry, pressure, temperature, weld procedure and governing code.
Manufacturing, inspection and documentation
Custom unequal-tee manufacture starts with drawing approval and requires verification of every end diameter, wall, center-to-end dimension, transition, branch profile and bevel. N08020 orders commonly define PMI, solution treatment, surface finish and the applicable construction-class/NDE requirements.
Heat-number traceability and PMI when specified.
All three end ODs/walls, center-to-end dimensions, transitions and bevels checked to drawing.
PT, MT where applicable, UT, RT or third-party witnessing to the ordered scope.
MTC, heat-treatment and inspection records compiled to project requirements.
RFQ checklist
- Complete material grade and UNS where applicable
- ASME B16.9 edition or approved project drawing
- Run, outlet and branch sizes
- Schedule or exact wall thickness at every end
- Seamless or welded construction/class
- Bevel detail and matching pipe dimensions
- Quantity, destination and required delivery date
- EN 10204 3.1, PMI, dimensional and NDE requirements
Frequently asked questions
What is a Alloy 20 custom unequal tee?
It is a Custom unequal butt-weld tee manufactured from ASTM B366/B366M, UNS N08020 iron-nickel-chromium-molybdenum-copper alloy. It is supplied to an approved drawing when the run ends, branch size or center-to-end dimensions fall outside the standard reducing-tee combination. The ordered material specification controls chemistry, mechanical properties, heat treatment and testing.
Which standard applies to this fitting?
The approved project drawing controls non-standard unequal-tee geometry. ASME B16.9 applies only to requirements and configurations explicitly included in the order and within its scope. The material basis is ASTM B366/B366M, UNS N08020 iron-nickel-chromium-molybdenum-copper alloy. The purchase order must state the required edition, construction, size, wall and supplementary examinations.
Where is Alloy 20 typically selected?
UNS N08020 is considered for sulfuric-acid handling, fertilizer production, chemical processing, pharmaceuticals and food-process equipment exposed to compatible corrosive media. Material suitability still depends on fluid chemistry, pressure, temperature, fabrication, corrosion allowance and the governing piping code.
Can heavy-wall and welded construction be supplied?
Yes, subject to manufacturing review. Provide the exact outside diameter, wall thickness or schedule, construction class, end preparation, quantity and NDE requirements so feasibility can be confirmed.
What should an RFQ include?
State the complete material grade, dimensional standard or approved drawing, run and branch sizes, schedule or exact wall, seamless or welded construction, bevel detail, quantity, destination, certification and inspection scope.
Product image is representative. Surface appearance varies by alloy, manufacturing route and finish.
Request a technical quotation
Send the material, size combination, wall, quantity, drawing or standard, and inspection requirements for review.
