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NPU and NPI sections: what is the difference?
NPU and NPI are trade designations used for steel sections. They are often used for U/channel and I sections respectively, but names can vary by supplier and standard. Confirm the section designation against the applicable catalogue before ordering.
Section shape
A U-shaped channel has a web and two flanges. An I-section uses a web to connect two flanges. ArcelorMittal lists UPN channels and IPN I-sections as separate product groups.
These designations are not interchangeable. Include the producer’s standard, section series and dimensions rather than only writing NPU or NPI on a request.
Structural selection
Section shape alone does not establish whether a profile is suitable for a project. Loads, span, supports, steel grade, buckling and connection conditions need to be checked in the structural design.
Information needed for a quote
- Section series and standard
- Nominal section size
- Length and quantity
- Grade and project use
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Confirm how NPU/NPI trade names map to UPN/IPN standard designations in the supplier catalogue. This article is not structural design advice.