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Connection Rosetta: NC ↔ IF, FH and REG
Datasheets in this category publish connections in one naming system and expect you to translate. Type either designation and the row you need highlights.
| NC designation | Legacy IF name | Typical string | Welong die collar |
|---|---|---|---|
| NC26 | 2-3/8 IF | 2-3/8″ drill pipe | 3 spans, 48–73 mm |
| NC31 | 2-7/8 IF | 2-7/8″ drill pipe | 3 spans, 69–93 mm |
| NC38 | 3-1/2 IF | 3-1/2″ drill pipe | 2 spans, 90–118 mm |
| NC50 | 4-1/2 IF | 4-1/2″ drill pipe | 1 span, 127 mm |
| — | 4-1/2 FH | Heavy-wall and collar strings | 2 spans, 120–141 mm |
| — | 6-5/8 REG | Large-bore collar strings | 1 span, 168 mm |
| NC46 | 4 IF | 4″ drill pipe | Not currently published ask us |
API Spec 7-2 — not 7-1 — governs rotary shouldered connections, and it standardises the number (NC), regular (REG) and full-hole (FH) styles. IF is a legacy designation that maps onto NC, not an API-published style, which is why both systems still appear side by side on supplier datasheets.
Running NC46, or a connection not listed here? Ask what we can build to that thread →
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