Flare Tube Fittings: 37° JIC (ISO 8434-2 / SAE J514) in Stainless & High-Nickel Alloys
A flare tube fitting is a mechanical tube connection. It seals by clamping a formed, flared tube end between the fitting nose and a threaded nut, giving a metal-to-metal cone seal with no ferrule. Crestflo builds the instrumentation-grade 37° flare (JIC) form per ISO 8434-2 / SAE J514 in stainless steel and high-nickel alloys, up to 2-inch (50 mm) OD. Working pressures reach 15,000 PSI, temperatures run as high as 350°C, and sour-service alloys meet NACE MR0175 / ISO 15156.
These are instrumentation 37° JIC flare fittings in stainless and high-nickel alloy. They aren't brass automotive, plumbing, or copper water-line flares, and they aren't aircraft AN hose ends.
Standard items ship from ready stock. Specials are made to order, and delivery on those runs 6-8 weeks. Request a quote for your line list.
Also Known As: 37° JIC, SAE J514, ISO 8434-2 & Flare Nut Fittings
JIC; JIC 37° fitting; JIC flare fitting; 37 degree flare fitting; SAE J514 fitting; or ISO 8434-2 fitting. Its aerospace cousin goes by AN, or MS/AN 37°. Buyers and specifiers don't all reach for the same term, and which one they use depends on the standard they're working from and the trade they're in.
The clamping nut gets ordered on its own plenty of times too, usually as a flare nut or flare nut fitting. Pull back and look at the whole family, and you'll see it called a flare fitting, flared tube fitting, flare tube union, or just a tube flare fitting.
Then there's the 45° geometry, a different animal entirely. Crestflo covers it on the 45° SAE flare fittings page, where it carries the SAE J512 designation. Most people just call it the SAE or inverted flare.
Flare Fitting Types & Forms: Unions, Elbows, Tees, Adapters & Flare Nuts
Crestflo makes the entire 37° flare component set, so you can put together a full tubing run from a single source. Listed below are the core forms. Each one comes in both stainless and high-nickel alloy.
| Component form | Description | Common designation |
|---|---|---|
| Flare union | Straight tube-to-tube 37° flare join | flare tube union |
| Male / female connector | 37° flare to threaded port (NPT, BSP, metric) | flare male connector |
| Elbow (45° / 90°) | Directional 37° flare turn | flare elbow fitting |
| Tee / cross | Three- and four-way 37° flare junction | flare tee |
| Adapter | Flare-to-NPT and flare-to-compression transition | flare fitting adapter |
| Bulkhead union | Panel- or wall-mounted 37° flare pass-through | flare bulkhead fitting |
| Flare nut | Threaded clamping nut for the flared tube end | flare nut fitting |
| Cap / plug | Line termination and port sealing | flare cap, flare plug |
Because the 37° flare pairs with Crestflo compression fittings through adapter ends, one system can mix flared and ferrule-sealed connections without re-plumbing.
Flare Fitting Sizes: 1/8-inch to 2-inch OD, Metric & JIC Dash Sizes
Crestflo makes its flare fittings in both imperial fractional and metric tube sizes, with end connections reaching up to 2-inch (50 mm) OD. The imperial range covers 1/8, 1/4, 3/8, 1/2, 3/4, 1, 1-1/4, 1-1/2 and 2-inch OD. Metric sizes start at 6, 8, 10-12 mm and run upward from there. JIC-standard dash sizes (-4, -6, -8, -12, -16) correspond to SAE J514 thread and seat dimensions. This flare fitting size chart brings imperial, metric and JIC dash sizing together in one flare tube fittings chart. It's built on the applicable ISO 8434-2 / SAE J514 tables, and it can be adjusted to specific requirements. Need the tube-end connection variant instead? Check the JIC-37 tube fitting page.
Flare Fitting Materials: 316L Stainless, 904L, Duplex, Inconel, Monel & Hastelloy
Crestflo stainless steel flare fittings come in 316L, 904L, duplex and high-nickel alloys, an alloy range the brass-dominated flare market simply doesn't offer. These stainless flare fittings, along with their CRA equivalents, keep brass, copper and aluminum out of the US instrumentation scope. Every flared connection is a corrosion-resistant grade.
- Austenitic stainless: 304/304L, 316/316L, 904L
- Duplex and super-austenitic: Duplex 2205, Super Duplex 2507, 254 SMO, AL-6XN, Alloy 20
- Nickel alloys: Inconel 625 / 825, Monel 400, Hastelloy C-276
- Titanium: Titanium Grade 2
Alloy compositions and mechanical properties are published in line with the relevant ASTM specifications, A269, A276 and A479, and full detail sits on each material page. Grades can be tailored to what's required.
High-Pressure Flare Fitting Ratings & Temperature Limits
Crestflo's 37° flare fittings carry a working-pressure rating up to 15,000 PSI and hold up to temperatures of 350°C, with the precise rating set by tube OD, wall thickness, alloy and component form; larger diameters derate, and the values follow whichever standard applies, customizable to the requirement. Rated to 350°C in the appropriate alloy, it also serves as a high-temperature flare fitting, standing up in conditions where a brass or elastomer-seated flare simply wouldn't survive the heat. Sour-service duty, meaning H₂S exposure, is met in the right alloys, which are supplied compliant with NACE MR0175 / ISO 15156. Every part carries heat and lot-number marking and ships with an EN 10204 3.1 material test certificate as standard, or 3.2 on request.
Flare Fitting Attribute Snapshot
| Attribute | Value | Basis |
|---|---|---|
| Sealing principle | 37° metal-to-metal flared cone, no ferrule | ISO 8434-2 / SAE J514 |
| Primary angle standard | 37° (JIC) | ISO 8434-2 / SAE J514 |
| Secondary angle | 45° (SAE inverted flare) | SAE J512 |
| Max OD | 2-inch (50 mm) | Crestflo range |
| Pressure rating | Up to 15,000 PSI (derates by size) | per applicable standard |
| Temperature rating | Up to 350°C | Crestflo range |
| Sizes | Imperial fractional, metric & JIC dash | ISO 8434-2 / SAE J514 |
| Materials | SS, duplex, nickel alloy, titanium | ASTM A269 / A276 / A479 |
| Traceability | Heat/lot marked; EN 10204 3.1 (3.2 on request) | EN 10204 |
| Sour service | NACE MR0175 / ISO 15156 alloys | NACE / ISO |
37° vs 45° Flare: The Two Flare Standards Explained
Two flare standards exist, and the seat angle is what tells them apart. SAE J514 and ISO 8434-2 define the 37° flare (JIC), the high-pressure option for instrumentation and hydraulic fluid-power lines. For automotive, refrigeration and plumbing work at lower pressures, SAE J512 governs the 45° flare (SAE). The two aren't interchangeable. A 37° flared tube won't seal against a 45° seat.
Crestflo's instrumentation range leads with the 37° JIC form. 45° SAE configurations get their own page, the 45° SAE flare fittings page; detailed ordering data for the 37° JIC line lives on the 37° JIC flare fittings page.
| Angle | Standard | Typical use | Pressure class |
|---|---|---|---|
| 37° (JIC) | SAE J514 / ISO 8434-2 | Instrumentation, hydraulics | High |
| 45° (SAE) | SAE J512 | Automotive, refrigeration, plumbing | Low–medium |
Flare vs Flareless (Bite-Type / Ferrule) Fittings
A flare fitting needs the tube end flared to 37° and seals against that formed cone. A flareless or bite-type fitting skips the flaring step entirely and seals when a ferrule bites into the unformed tube OD. Flare connections hold up well on high-vibration hydraulic lines and work best for re-usable joints where a flaring tool is already on hand; flareless connections let you make up a joint faster in the field, especially when proper tube prep just isn't practical. For the bite-type option, Crestflo's DIN 2353 fittings and ferrule-less fittings pages cover the details. As for single-flare versus double-flare, that distinction comes down to how the tube end gets prepped before assembly, nothing more.
Hydraulic & Instrumentation Applications for Flare Fittings
Hydraulic flare fittings (37° JIC) are specified wherever a vibration-resistant, re-makeable high-pressure connection is needed: hydraulic and fluid-power circuits, instrumentation tubing runs, high-pressure gas lines, high-purity flare runs for analytical and calibration gases, process analyzer plumbing, and oil-and-gas service where sour (H₂S) exposure drives NACE alloy selection. The 37° JIC seat is the fluid-power industry's default high-pressure flare, which is why it dominates hydraulic tubing hardware. Where that same 37° seat is carried on a compression body as an end connection rather than a flared tube join, the part is ordered as JIC hydraulic fittings, see the JIC-37 tube fitting page.
Standards, Conformance & Proof
Crestflo flare fittings match the dimensional requirements of ISO 8434-2 and SAE J514 for the 37° form, so they seat and thread exactly as the standard calls for. Material grades come from the applicable ASTM A269 / A276 / A479 specifications, and sour-service alloys are sourced to NACE MR0175 / ISO 15156. Every part ships with an EN 10204 3.1 certificate, complete with heat and lot traceability. Crestflo's manufacturing operations hold ISO 9001, 14001, and 45001 certification, along with PED certification. Validation covers a lot of ground: hydraulic proof, burst, and impulse testing; pneumatic testing; flexure-fatigue and rotary-flex testing; vibration and thermal-cycling; pull-out and vacuum testing. Positive material identification (PMI) and in-house NDT round out the process. Destructive testing happens at ISO/IEC 17025-accredited laboratories, and third-party inspection is available on request. Full standard references sit on the instrumentation fitting standards hub.
Cross-Reference & 37° JIC Interchange
The 37° JIC flare is a dimensional standard, defined in SAE J514 and ISO 8434-2. That's why Crestflo flare fittings match other manufacturers' 37° JIC flare fittings dimensionally and interchange with them without issue. Seat angle, thread, and dash sizing all come from the standard itself, not from any single company's proprietary design. For a branded equivalence against a specific make, reach out to our engineering team for a cross-reference through the tube fitting cross-reference hub. Swagelok®, Parker®, and other marks belong to their respective owners. Crestflo is an independent manufacturer and has no affiliation with them.
Request Flare Tube Fittings & Product Data
Datasheets and CAD models are there for the asking. Need to order, price, or spec out 37° JIC flare fittings? Give the Crestflo engineering team your alloy, size, thread and component form details. Reach the US team at sales@crestflousa.com · +1 346 594 9005 (Houston, TX). Standard items go out from stock on hand; specials get built to order, with delivery running 6-8 weeks. Request a quote or contact us and send over your line list.
Why Crestflo for Flare Tube Fittings
Crestflo is the instrumentation division of an export house that's been in business for four decades and carries Government of India recognition, with a proven track record of deliveries across the Middle East. That engineering discipline sits behind a catalog built specifically for US buyers.
Where the flare fittings stand apart is alloy depth. Crestflo offers 316L through Inconel, Monel, Hastelloy, duplex and titanium, a range the brass-led flare market simply can't match. Standard product comes from Indian mills, though US or European melt is available on request, and every order carries full material traceability.
Add heat-number marking on each part, EN 10204 3.1 certification as standard, and manufacturing certified to ISO 9001, 14001 and 45001, plus PED. MOQs are small, private-label runs are available, and delivery runs 6-8 weeks against the 20-plus weeks typical of the major suppliers. We Engineer Confidence.
Flare Tube Fittings FAQ
What is a flared tube fitting?
A flared tube fitting seals by clamping a 37°-flared tube end between the fitting nose and a threaded nut. It's a metal-to-metal cone seal, with no ferrule involved. The tube end has to be formed to that 37° angle before you can even assemble it.
Is a flare fitting the same as an NPT fitting?
No. A flare fitting seals against a 37° metal cone. NPT, by contrast, seals on tapered pipe threads per ASME B1.20.1. Those are two distinct sealing principles, and that's why Crestflo makes flare-to-NPT adapters for moving between them.
What are the two standards for flare fittings?
The 37° flare comes from SAE J514 and ISO 8434-2, the JIC form you'll find in instrumentation and hydraulics work. The 45° flare, by contrast, is defined under SAE J512 and shows up in automotive, refrigeration and plumbing applications. Swap one for the other and you're asking for trouble; they don't interchange.
What angle are Crestflo flare fittings?
Crestflo's default is the 37° JIC flare, built to ISO 8434-2 and SAE J514. Need a 45° SAE flare instead? That's handled on a separate page. Just confirm the exact 45° requirement on your RFQ.
What materials are available for flare tube fittings?
Materials on offer span the stainless family (304/304L, 316/316L and 904L) alongside duplex and super-duplex, Inconel, Monel, Hastelloy, Alloy 20 and titanium Grade 2. Brass, copper and aluminum sit outside the US instrumentation scope.
What pressure and temperature can flare fittings handle?
You can push it to 15,000 PSI and 350°C, though that ceiling shifts with tube OD, wall thickness, alloy and the form the component takes. Go bigger in diameter and the numbers come down. Figures track whatever standard applies, and we'll tailor them to the job at hand.
Are Crestflo flare fittings NACE-compliant for sour service?
Yes. We've got flare fittings available in NACE MR0175 / ISO 15156 compliant versions, made from the appropriate high-nickel and duplex alloys for sour (H₂S) service.
Can flare fittings connect to compression tube fittings?
Yes. Crestflo's 37° flare fittings work with compression fittings via flare-to-compression adapters, so a single run can combine flared and ferrule-sealed connections.
Do Crestflo flare fittings interchange with other brands' 37° JIC fittings?
Because 37° JIC dimensions come from a recognized standard (SAE J514 / ISO 8434-2), Crestflo flare fittings match the dimensions of and interchange with other manufacturers' 37° JIC fittings. Ask the engineering team for your branded cross-reference.
What is the correct flare fitting torque for assembly?
Tighten the flare fitting to the torque value, or the flats-from-finger-tight figure, listed in the applicable SAE J514 / ISO 8434-2 assembly table for that tube size and thread. The 37° cone seats metal-to-metal. Over-torque it and you distort the flare; under-torque it and it leaks. Torque figures follow the applicable standard, though they can be adjusted to suit specific requirements.
What is the lead time and minimum order for flare fittings?
Ready stock covers the standard items. Specials are made to order, with delivery running 6-8 weeks. Small minimum order quantities work fine, and private-label programs are on offer too.
Related Products & Resources
- 37° JIC flare fittings: everything you need for ordering the 37° JIC style.
- 45° SAE flare fittings: the SAE J512 inverted flare, spelled out in full.
- JIC-37 tube fittings: a JIC end connection paired with a compression body.
- Compression tube fittings: flareless designs and ferrule-sealed alternatives worth considering.
- 316 / 316L material, primary flare-fitting alloy
- Tube fitting cross-reference, request a branded interchange