References & Important Notices
- Source: SAE International, Aerospace Standard AS5202 Revision A — “Port or Fitting End, Internal Straight Thread, Design Standard.” Custodian: SAE G-3/G-3B. Drawings are interpreted in third angle projection.
- No SAE affiliation or endorsement. SAE International has not participated in the development of this lookup tool and does not approve or endorse it. Verify all dimensions against the current issue of SAE AS5202 before use in design.
- Tap drill and minor diameter (thread note on the figure). The internal minor diameter is the UNJ minimum of SAE AS8879, D1 min = D − 1.125 P cos 30°, plus the ASME B1.1 Class 3B minor-diameter tolerance, 0.05 P2/3 + 0.03 P/D − 0.002. These limits match the published AS8879D values in Yamawa, Recommended Drill Sizes for Tapping Internal UNJ Threads for every size it lists (1/4-28 through 1-12 UNJF), to within .0007″; see also Walter, Thread pilot hole diameters. Tap drills for 1/4-28 through 1-12 are Yamawa’s. Yamawa does not list 13/16-16 UNJ or the 12-pitch sizes above 1″; for those the drill is the standard size inside the same 3B band, placed as Yamawa places its own (19.20 mm for 13/16-16; the 1/64″ size about one-third into the band for the 12-pitch sizes). Those are calculated, not published — confirm them against the current AS8879 before release. Drills above about 1″ are often replaced by boring to the same diameter.
- Related standards. Use with flared tube fittings per SAE AS4841; interpret drawings per SAE ARP4296; dimensioning and tolerancing per ASME Y14.5M-1994.
- Verify critical dimensions. Always confirm fitting-end dimensions against the current SAE AS5202 standard for safety-critical or pressure-containing applications. This tool is a reference aid, not a substitute for engineering judgment.