SAE J512 45 degree flare brass nut — engineering drawing (Brassland).
Specification
| Standard | SAE J512 — 45° flare tube fittings (thread sizes verified below) |
| Type | Brass flare nuts for 45° flared tube; inverted-flare nuts on request |
| Tube sizes | 1/4 to 5/8 in. OD (45° series); other sizes to your drawing |
| Body dimensions | Per your drawing — confirmed at quotation |
| Material | C36000 free-machining brass (UNS) — EN twin CW614N (CuZn39Pb3); lead-free C69300 / CW724R on request |
| Certificate | EN 10204 3.1 per shipment; 3.2 on request |
Thread chart — SAE 45° flare (J512)
| Tube OD (in.) | Thread | TPI |
|---|---|---|
| 1/4 | 7/16-20 | 20 |
| 5/16 | 1/2-20 | 20 |
| 3/8 | 5/8-18 | 18 |
| 1/2 | 3/4-16 | 16 |
| 5/8 | 7/8-14 | 14 |
Tube-to-thread mapping per SAE J512, 45° flare series, verified against two independent published references (July 2026).
Inverted-flare series — do not mix with the 45° chart
| Tube OD (in.) | Thread (45° inverted flare) |
|---|---|
| 1/4 | 7/16-24 |
| 5/16 | 1/2-20 |
| 3/8 | 5/8-18 |
| 7/16 | 11/16-18 |
The SAE J512 inverted-flare series uses its own threads: a 1/4 in. tube takes 7/16-24 inverted-flare versus 7/16-20 standard 45° flare. The two series must never be mixed on one assembly or drawing.
JIC 37° caution
Several 45°-flare threads (7/16-20, 1/2-20, 3/4-16, 7/8-14) share their thread form with JIC 37° fittings — but the seat angles differ (45° versus 37°), so the two are not interchangeable. Specify the seat angle on your drawing. Dash-size numbering conventions vary between publishers, so we quote against tube OD and thread callout, not dash codes.
Applications
SAE 45° flare brass nuts connect flared copper, aluminum and brass tube in US-market plumbing, LP and natural gas appliance connections, refrigeration and automotive lines. Brassland machines the nuts (and mating machined fitting components) to your drawing; flare nut body dimensions are confirmed on the drawing supplied with the quotation. The metric bite-type equivalent system is on our DIN 2353 cutting-ring page.
Imperial & UNC range
Related pages
DIN 2353 bodies, nuts and DIN 3852 ports.
View →Metric equivalentMetric bite-type tube fitting system.
View →ProductInch-series nuts to ASME B18.2.2.
View →IndustryFlare and compression components.
View →IndustryRefrigeration line hardware.
View →MaterialUS free-machining brass datasheet.
View →Quote in 24 hours.
Give the standard, thread, finish and quantity. We machine inch-series brass parts in Jamnagar, India, and export to 40+ countries.
Sources & references
Tube-to-thread mappings for both the 45° flare and inverted-flare series verified against two independent published SAE J512 thread-specification references (July 2026). Flare nut body dimensions are not standardized in a publicly verified table and are therefore quoted per drawing. Governing document: SAE J512.
Frequently asked questions
7/16-20 per SAE J512. The 7/16-24 thread belongs to the separate SAE inverted-flare series — the two must never be mixed on one assembly.
No. Some sizes share the same thread form (7/16-20, 1/2-20, 3/4-16, 7/8-14), but the seat angles differ — 45 degrees versus 37 degrees — so they are not interchangeable. Always specify the seat angle on the drawing.
A nut for the SAE J512 inverted-flare series, where the seat geometry is reversed and the threads differ from the standard 45 degree series: 1/4 in. tube takes 7/16-24, 5/16 takes 1/2-20, 3/8 takes 5/8-18 and 7/16 takes 11/16-18.
Flare nut body dimensions are not published in a standardized, publicly verified table, so we machine them to your drawing — or supply our drawing for approval with the quotation. Thread callouts follow the verified SAE J512 chart on this page.
C36000 free-machining brass (EN twin CW614N / CuZn39Pb3) as standard; lead-free silicon brass (C69300) on request for potable-water work. EN 10204 3.1 certificates per shipment.