45° SAE Flare Fittings: Stainless Steel & High-Nickel Alloy (SAE J512)
A 45° SAE flare fitting is a tube fitting that forms a metal-to-metal seal when a 45° flare on the tube end is clamped between the fitting nose and a flare nut, following the seat geometry defined by SAE J512. Crestflo builds this connection in stainless steel and corrosion-resistant alloys for corrosive gas, refrigeration and low-to-medium-pressure fluid lines, the higher-integrity service where brass commodity fittings fall short. These are industrial and instrumentation fittings (SAE J512 seat angle), distinct from the brass refrigeration commodity and from the 37° JIC/AN flare, which uses a different seat angle and is not interchangeable.
Ready stock for standard items · made-to-order for specials · 6–8 week delivery. Request a quote or browse all flare fittings.
Also Known As: SAE 45° Flare, SAE J512 Fitting & 45 Degree Flared Tube Fitting
These fittings are also specified as SAE 45 degree flare fittings, SAE flare fittings, 45° flare fittings, 45 degree flared tube fittings, single 45° flare fittings, and "SAE 45." The governing designations are SAE J512 (the fitting standard) and SAE J533 (which defines how the flare is formed on the tube). The straight (non-sealing) UNF thread on the nut supplies clamp load only; the seal is metal-to-metal at the 45° flare cone/seat, not on the thread. Buyers sometimes confuse the single 45° flare with a double flare or with the inverted flare, both distinct joints covered in the related-connections notes below.
45° SAE Flare Fitting Attributes: Seat Angle, Thread Form & Materials
The table gives the standard published attributes of the 45° SAE flare connection; values follow the applicable standard and are customizable to requirement. Crestflo-specific ordering codes and any certified rating that differs from the standard are available from the engineering team on request.
| Attribute | Value |
|---|---|
| Working principle | Metal-to-metal seal; a 45° flare on the tube is clamped between the fitting nose and a flare nut |
| Seat angle | 45° to the fitting axis (SAE J512), versus 37° for JIC/AN flare |
| Governing standards | SAE J512 (fitting), SAE J533 (flare forming) |
| Thread form | SAE straight UNF flare thread (per SAE J512; see size table) |
| Pressure class | Low-to-medium-pressure connection; ratings per applicable standard, customizable to requirement |
| Size range (tube OD) | 1/8" to 3/4" per SAE J512; larger flares such as 7/8" OD (1-1/4-12 UNF) available to requirement; imperial and metric, customizable to requirement |
| Material options | 304/304L, 316/316L, 904L, Duplex 2205, Super Duplex 2507, 254 SMO, Alloy 20, Monel 400/K500, Inconel 625/825, Hastelloy C-276, Titanium Gr2 |
| Traceability | EN 10204 3.1 MTC standard (3.2 on request), heat/lot number on every part |
| Origin / melt | Indian origin; US / European melt available on request, with full material traceability |
45° SAE Flare Fitting Sizes (1/8"–3/4") & UNF Thread Chart
Standard SAE 45° flare tube outside diameters and their corresponding straight UNF flare threads are shown below, with metric OD equivalents. Dimensions follow SAE J512 and are customizable to requirement; imperial and metric are available on every size. The 1/8"–3/4" band is the SAE J512 range; larger flares such as 7/8" OD (1-1/4-12 UNF) are available to requirement for low-to-medium-pressure lines.
| Tube OD (in) | Tube OD (mm) | SAE 45° flare thread (UNF) |
|---|---|---|
| 1/8" | 3.18 | 5/16-24 |
| 3/16" | 4.76 | 3/8-24 |
| 1/4" | 6.35 | 7/16-24 |
| 5/16" | 7.94 | 1/2-20 |
| 3/8" | 9.53 | 5/8-18 |
| 1/2" | 12.70 | 3/4-16 |
| 5/8" | 15.88 | 7/8-14 |
| 3/4" | 19.05 | 1-1/16-14 |
45° SAE Flare Fitting Types: Union, Tee, Elbow, Adapter, Nut, Cap & Plug
The 45° SAE flare seat is offered across the full range of connection bodies. End configurations and adapters are made to order in the alloys listed above.
| Configuration | Ends / notes |
|---|---|
| Union | Flare × flare, straight through |
| Tee / cross | Three- or four-way flare junctions |
| Elbow | 45° or 90° flare × flare |
| Male / female connector | Flare × NPT (male or female pipe thread) |
| Adapter | SAE flare ↔ NPT, SAE flare ↔ inverted flare |
| Flare nut | Straight UNF nut for the flared tube |
| Cap / plug | Line termination |
Stainless Steel & Alloy 45° Flare Fittings: Beyond Brass
The common 45° SAE flare is a brass refrigeration and automotive commodity. Crestflo's differentiation is the corrosion-resistant version: stainless steel and high-nickel alloys for media, temperatures and cleanliness levels that brass cannot serve. US scope excludes brass as a headline material; every family below is offered in instrumentation flare form and links to the grade's material page.
| Family | Grades | Why choose |
|---|---|---|
| Austenitic stainless | 316/316L, 304/304L | General corrosion resistance, weldability, broad chemical service |
| Super-austenitic | 904L, 254 SMO | Chloride and sulfuric-acid resistance |
| Duplex / super duplex | Duplex 2205, Super Duplex 2507 | High strength plus chloride stress-corrosion resistance |
| Nickel alloys | Monel 400, Inconel 625, Hastelloy C-276 | Sour service, halide and reducing-acid environments |
| Titanium | Titanium Gr2 | Seawater and oxidising chloride service |
45° SAE vs 37° JIC Flare: Different Seat Angles, Not Interchangeable
The defining difference between the two flare families is the seat angle: SAE uses 45°, while JIC/AN uses 37°. The angles are not interchangeable, mixing a 45° fitting with a 37° flared tube (or the reverse) leaves a line-contact seal that leaks and can gall the seat. Match the flare angle throughout the assembly.
| Property | 45° SAE flare (J512) | 37° JIC/AN flare (J514, ISO 8434-2) |
|---|---|---|
| Seat angle | 45° | 37° |
| Typical service | Gas, refrigeration, low-to-medium pressure | Hydraulics, instrumentation, higher pressure |
| Thread | Straight UNF | Straight UN/UNF |
| Interchangeable with the other angle? | No, never mix 45° and 37° | No, never mix 37° and 45° |
For the 37° connection, see 37° JIC/AN flare fittings. For a comparison of straight-thread seat styles, see JIC vs ORB.
45° SAE Flare Fitting Applications: Gas, Refrigeration & Sample Lines
Corrosion-resistant 45° SAE flare fittings suit service where a brass flare would corrode or contaminate the line:
- Corrosive and instrument gas lines, including propane / LP gas service, where alloy integrity matters more than the low cost of brass.
- Refrigeration and HVAC / AC with aggressive refrigerants, stainless and nickel-alloy flares resist media that attack brass.
- Analytical and sampling systems, clean, traceable sample lines for stainless instrument tubing lines.
- Marine and shipbuilding, chloride-laden environments.
- Hydraulics and instrument air, where a 45° flare joint is specified.
Related Connections: Inverted Flare, Double Flare & Compression Fittings
The 45° SAE flare is a single flare. An inverted flare places the 45° seat on the inside of a female fitting and is common in brake and low-pressure lines, a distinct product, not interchangeable with a standard SAE flare. A double flare folds the tube wall over on itself for extra strength on softer tube but is still a joint geometry, not a fitting family. For higher-pressure or vibration service, a double-ferrule compression tube fitting or a JIC-37 tube-fitting end is usually the better connection; SAE-ORB covers straight-thread port sealing.
Standards, Certification & Traceability
Crestflo 45° SAE flare fittings are manufactured to SAE J512 seat geometry; interchange with other SAE 45° flare hardware is dimensional, per that standard. Crestflo is ISO 9001 / 14001 / 45001 & PED certified. On qualifying alloys the fittings are supplied to NACE MR0175 / ISO 15156 for sour service. Every part ships with a heat/lot number and an EN 10204 3.1 material test certificate (3.2 on request), and testing and inspection follow the Crestflo QA regime, see traceability and testing & inspection. Origin and melt are handled transparently: Indian origin, with US / European melt available on request, see US-origin & compliance. Datasheets and CAD models are available to customers on request.
Products & Ordering: Request a Quote or Cross-Reference
Configure your 45° SAE flare fittings by tube OD, body style, end connection and alloy, and Crestflo will confirm availability and lead time. Standard items ship from ready stock; specials are made to order on a 6–8 week delivery. To match an existing Parker®, Swagelok® or brass SAE 45° flare part, request your cross-reference from our engineering team and we will return the Crestflo equivalent. Parker® and Swagelok® are trademarks of their respective owners.
Why Crestflo for 45° SAE Flare Fittings
Crestflo is the instrumentation division of a four-decade-old, Government-of-India-recognized export house with a long Middle-East delivery record, the manufacturing depth behind a focused US-serving brand.
- Stainless & CRA range brass suppliers can't match, 316L through Monel, Inconel, Hastelloy and titanium for corrosive service.
- 6–8 week delivery versus the 20+ weeks typical of the majors; lead time is a published capability.
- Small MOQ and private label for distributors and OEMs.
- Full traceability, heat number on every part plus EN 10204 3.1 MTC.
- Imperial and metric on every size, with finishing options including electropolish, passivation and silver anti-galling.
- HTML-native specs, not buried PDFs; datasheets and CAD on request.
We Engineer Confidence.
Frequently Asked Questions
What is a 45° SAE flare fitting?
A 45° SAE flare fitting is a tube fitting that seals via a 45° flare formed on the tube end and clamped by a straight-thread flare nut, per SAE J512. It is common in gas, refrigeration and low-to-medium-pressure fluid lines. Crestflo builds it in stainless steel and corrosion-resistant alloys rather than brass.
What is the difference between 37° and 45° flare fittings?
The difference is the seat angle. JIC/AN flare uses 37° (SAE J514 / ISO 8434-2) for higher-pressure hydraulics and instrumentation; SAE flare uses 45° (SAE J512) for gas, refrigeration and low-to-medium-pressure service. They are not interchangeable, mixing the angles leaves a poor seal that can leak or gall.
Can I use a 45° SAE fitting with a 37° JIC flare?
No. The seat angles differ, so a 45° fitting will not seal reliably against a 37° flared tube and the mismatch can gall the seat. Use one matching flare angle throughout the assembly.
What is a 45 degree pipe fitting called?
In tube systems it is a 45° SAE flare fitting (or "SAE flare"). Note that "45 degree" can also describe a 45° elbow configuration, a bend angle rather than a seat angle, so confirm whether you mean the flare seat or the fitting geometry.
Are "SAE" and "flare" the same thing?
No. "Flare" is the joint type, a flared tube end clamped by a nut. "SAE 45°" specifies the flare's seat angle and thread standard (SAE J512). A flare can be a 45° SAE flare or a 37° JIC flare, which are different and not interchangeable.
Do you offer 45° SAE flare fittings in stainless steel and alloys, not just brass?
Yes, that is Crestflo's differentiation. The line is offered in 316L, 904L, Duplex, Monel, Inconel, Hastelloy and titanium for corrosive and high-integrity service that brass cannot handle. US scope leads with stainless and corrosion-resistant alloys rather than brass.
Do you supply a 45° flare tool or flaring tool?
No. A 45° flare tool (flaring tool) is the forming tool that swages the 45° cone onto the tube end per SAE J533, it is workshop equipment, not a fitting, and is out of scope for Crestflo. We supply the 45° SAE flare fittings, nuts and adapters that seal against a tube already flared to the correct 45° angle; the flaring tool itself is sourced separately.
What sizes and threads are available?
The 45° SAE flare spans 1/8" to 3/4" tube OD with straight UNF flare threads, per SAE J512; larger flares such as 7/8" OD (1-1/4-12 UNF) are available to requirement. Imperial and metric are available and dimensions are customizable to requirement. See the size and thread chart above for standard tube-OD-to-thread pairings.
What certification, lead time and origin come with the fittings?
Fittings ship with a heat number on every part and an EN 10204 3.1 material test certificate (3.2 on request); Crestflo is ISO 9001 / 14001 / 45001 & PED certified, with NACE MR0175 / ISO 15156 on qualifying alloys. Standard items ship from ready stock and specials are made to order on a 6–8 week delivery. Origin is Indian, with US / European melt available on request.