AS5202 Port Chart —
Straight Thread Fitting End Dimensions

What AS5202 Covers

AS5202 is the SAE Aerospace Standard for the machined port that accepts a straight-thread tube fitting with an O-ring seal: the internal thread, the sealing counterbore the O-ring compresses into, the spotface the fitting shoulder seats against, and the depths and tolerances tying them together. It was issued as the replacement for MS33649 and mates with fitting ends per AS4875.[1]

Two details separate an AS5202 port from a generic tapped hole. First, every thread is a J-form thread per AS8879 class 3B, including several diameter-pitch combinations (.8125-16, 1.0625-12, 1.1875-12 and up) that exist mainly as port threads. The J form means an enlarged minor diameter, so use the J minor from our UNJ chart, not a standard tap drill. Second, the counterbore and spotface are sealing surfaces: 32 Ra where the standard flags them, against 125 Ra for the rest of the port, with the .005 runout and perpendicularity controls of the figure. A port that gauges fine on thread but was cut with a worn spotface tool will still leak.[1]

AS5202 Dimension Table

All values in inches from AS5202 Tables 1A and 1B, with each column's tolerance in its header. General tolerances where not stated: linear ±.005, angles ±0°30'.[1]

Machining Notes

Port tooling. Production shops cut AS5202 ports with dedicated port contour cutters that machine the counterbore, seal face, and spotface in one pass, which is how the concentricity and finish requirements are met reliably. Single-point profiling on a lathe or mill works for low volumes; budget for gauging either way.

Threading. The B dimension is the minimum full-thread depth for a blind design, and J is the minimum depth of the full-diameter bore: it is measured to where the drill stops cutting full diameter, and the drill point cone extends beyond it before the smaller ⌀C passage continues through. Because the thread is J-form, verify the minor diameter against the AS8879 3B limits rather than a UN chart; our UNJ page tabulates the basic J minors and suggested drills.

Callouts. A tabulated drawing may simply state "FITTING END PER AS5202"; an individual port is called out by size code, for example AS5202-08 for the 1/2 inch tube size. Edge breaks are .003 to .015 unless otherwise specified, and interpretation follows ARP4296 with ASME Y14.5M dimensioning.[1]