Elbow Tube Fittings: 90° & 45° Compression Elbows in Stainless & High-Nickel Alloys

An elbow tube fitting is a compression fitting, either double-ferrule or single-ferrule, used in instrumentation tubing to turn a run 90° or 45° while sealing on the tube's outside diameter under nut torque. It's the directional member of the tube-fitting family. A union or connector just carries a run straight through; an elbow changes direction without putting a bend in the tube itself.

Scope note: on this page, "elbow" refers to an instrumentation compression elbow tube fitting made from stainless steel or high-nickel alloy, used in fluid and gas systems. It doesn't mean a copper or PVC plumbing sweat elbow, and it isn't a threaded or welded pipe elbow either.

Crestflo runs the instrumentation arm of an export house that's been recognized by the Government of India for four decades. These elbows come out as drop-in replacements built for the US market, shipped in 6-8 weeks. We Engineer Confidence.

Elbow Tube Fitting: Also Known As

Buyers and specifiers know this part by a dozen different names, and the same fitting ships under any of them: tube fitting elbow, tube elbow fitting, tube elbow, compression elbow fitting, compression tube elbow, instrumentation elbow fitting, instrumentation tube fitting elbow and double-ferrule elbow. By angle, it shows up as a 90 degree (90°) elbow or a 45 degree (45°) elbow, sometimes listed as tube fitting 90 degree or 90 degree tube connector. By configuration, it's a union elbow, male elbow, female elbow, elbow connector, elbow connector fitting, reducing elbow, bulkhead elbow or positionable (swivel) elbow. When a job calls for a two-ferrule brand pattern, Crestflo supplies its elbows as a dimensional interchange for it.

What Is an Elbow Tube Fitting?

An elbow tube fitting changes the direction of an instrumentation tube run at a fixed angle, and it seals mechanically. The nut drives a front and back ferrule (in a double-ferrule design) or a single ferrule onto the tube OD, forming a leak-tight metal grip. No threading, no flaring, no welding of the tube. That's what sets it apart from a straight union or connector, which carry the line straight through, and from a branch tee or cross, which split it instead. The seal forms on the tube surface, not on a pipe thread, so a tube elbow counts as a compression fitting rather than a pipe fitting. You can browse the full family on the tube fittings hub at Crestflo.

How a Compression Elbow Seals: Single & Double Ferrule

Under make-up, the nut drives the ferrule set forward. In a double-ferrule elbow, the back ferrule hinges and grips the tube, while the front ferrule seals against the fitting body; together they deliver both a gas-tight seal and a firm mechanical hold. A single-ferrule elbow asks one ferrule to handle both jobs at once. Crestflo makes both designs, offering hardened or non-hardened ferrules depending on the requirement, along with finishes such as electropolish, passivation and silver anti-galling plating. Anyone weighing the geometry and the trade-offs should check single vs double ferrule and hardened vs non-hardened ferrules. For spares, the nut and ferrule, single-ferrule and ferrules pages cover it.

90° vs 45° Elbows: When to Use Each

Both angles are standard elbow geometry; the choice follows the routing.

Worth clarifying the difference here. A tube elbow turns a line and seals against the tube OD with a ferrule. By contrast, a pipe elbow, whether butt-weld or socket-weld, gets welded or threaded onto pipe ends. That's a different product entirely. The instrumentation elbow covered here is the compression style. Crestflo's butt-weld and socket-weld fittings handle the weld-end side of things.

Elbow Configurations: Union, Male NPT, Female NPT, Reducing, Bulkhead & Positionable

This elbow comes in several end configurations. A union elbow turns 90° or 45° between two tube runs of the same OD. Male, female, reducing, bulkhead and positionable builds work differently: each swaps one end for a thread, a different OD, or a panel-mount body. Values follow standard instrumentation practice, and the build itself can be customized to whatever the application requires.

A quick note on terminology: a male elbow also goes by male elbow connector, and a female elbow by female elbow connector. Either name gets you the same part. A "street elbow" is actually a pipe-fitting pattern, with one male end and one female end, and here it's listed as a male or female tube elbow rather than under its plumbing name. Straight equivalents sit on sibling pages. For a straight tube-to-pipe run, check the male connector or female connector.

Elbow Thread & End Options: NPT, BSPT, BSPP, ISO Parallel, JIC 37° & Metric

If an elbow ends in a thread, specify the form. Thread dimensions come from the published standards, NPT under ASME B1.20.1 being one example. Values follow whatever standard applies, and they're adjustable to the requirement at hand.

Elbow Materials: 316/316L Stainless, Duplex, Inconel, Monel & Titanium

The standard build is a 316/316L stainless steel elbow tube fitting, most systems call for a stainless elbow, and that's the default. But the shop machines the full instrumentation alloy range; brass, aluminum, and copper fall outside that scope. Every part gets a heat/lot number along with EN 10204 MTC 3.1 (3.2 available on request). Grade compositions appear against their ASTM standards on each material page.

For sour-service duty, elbows come NACE MR0175 / ISO 15156 compliant. Check Crestflo's full materials library for composition, PREN and mechanicals by grade.

Elbow Sizes (1/16″–2″ / 3–50 mm): Both Imperial and Metric

Tube-fitting ends run up to 2″ (50 mm) OD, and there's an imperial and metric option on every fitting. Where a job crosses systems, the two can be paired on the same line. The metric elbow tube fitting comes in 6, 8, 10 and 12 mm OD, right alongside the full imperial range.

The complete range is on the tube fitting size chart.

Elbow Pressure & Temperature Ratings

For high-pressure elbow tube fitting service, the working envelope isn't set by one fixed number. It comes down to the tube OD, wall thickness and alloy. As an all-metal fitting with no elastomer seal, the elbow's temperature limit follows the alloy and tube itself, not some seat material. Working pressures come from the standard tube pressure-allowable tables: ASTM A269 / A213 tube data evaluated per ASME B31.3, for example. Values follow whichever standard applies, and can be adjusted to fit the requirement. Need a rating for a specific OD, wall, alloy and angle combination? Ask Crestflo's engineering team for the rated build, and take a look at the pressure-temperature derating and tube sizing and wall thickness guides.

Ordering & Part-Number Cross-Reference

Configure an elbow by angle (90° or 45°), end configuration (union, male, female, reducing, bulkhead or positionable), tube OD and thread, alloy, ferrule type (single or double, hardened or non-hardened) and finish. Crestflo's ordering-code series and any competitor part-number equivalents are provided on request rather than published, request the ordering-code guide, or request your Swagelok® or Parker® cross-reference, from our engineering team via the Swagelok cross-reference page or a direct RFQ. Datasheets and CAD models are available to customers on request. Swagelok® is a trademark of Swagelok Company; Parker® is a trademark of Parker Hannifin. Crestflo is not affiliated with or endorsed by either.

Elbow Cross-Reference: Drop-In Interchange for Swagelok, Parker & Hy-Lok

Crestflo elbows are built to swap dimensionally with the major two-ferrule systems, and they're qualified to ASTM F1387, the test standard that lets an equivalent elbow work as a true drop-in rather than a mere look-alike. Need a match for a specific brand? Pull the details from the Swagelok cross-reference, Parker A-Lok cross-reference, or Hy-Lok cross-reference page, or browse the whole set on the cross-reference hub. These equivalents are framed only as interchange, never as compatibility or as genuine parts.

Standards, Testing & Traceability

Crestflo compression elbow tube fittings meet ASTM F1387, the standard behind the drop-in interchange claim. The elbows carry ISO 9001, ISO 14001, ISO 45001 and PED certification, and in the appropriate alloys they're supplied compliant with NACE MR0175 and ISO 15156. We hold the standard approvals that apply to compression tube fittings.

Testing covers hydraulic proof, burst and impulse, pneumatic, vibration, thermal cycling, pull-out and vacuum, along with PMI and in-house NDT. Destructive testing happens at ISO/IEC 17025-accredited labs, and third-party inspection is available on request. Crestflo marks every part with its heat/lot number, see material traceability.

Why Crestflo for Elbow Tube Fittings

• ASTM F1387 drop-in: this isn't a look-alike claim. Dimensions match the majors, and test qualification backs it up.
• 6-8 week delivery: standard items ship from stock; specials get made to order. Compare that to the 20+ weeks buyers have come to expect from the incumbents.
• Full alloy range: 316 and 316L, Duplex, Inconel, Monel, Hastelloy, Titanium. Most tube-fitting suppliers stop at stainless.
• Both imperial and metric, 90° and 45°, single and double ferrule, hardened or non-hardened.
• Heat-number traceability + MTC on every part; NACE compliance for sour service.
• Small MOQ and private label. This is the instrumentation division of an export house recognized by the Government of India, one with a proven delivery record across the Middle East.

Origin is no secret here: Indian origin material, with US or European melt available on request and full material traceability included. For domestic-melt or TAA requirements, Crestflo's US-origin compliance page has the details.

Applications

Elbow tube fittings turn instrumentation and hydraulic lines for Crestflo across a wide range of industries. That's oil and gas, offshore and subsea operations, petrochemical plants, hydrogen systems and semiconductor manufacturing. It also covers analytical sampling systems, instrument air and hydraulics systems.

Request an Elbow Quote

Send along your specification: angle, end configuration, tube OD and thread, alloy, ferrule, and finish. From there, you'll get a quoted, drop-in build. The primary route is to request a quote. Need something less formal first? You can request a sample, ask for the line card, look into the private-label program, or speak with an engineer through OEM support. Reach US sales at sales@crestflousa.com · +1 346 594 9005 · Houston, TX.

Reviewed by the Crestflo Engineering Team

Frequently Asked Questions

Related Pages

• All tube fittings
• Union · Tee · Cross · Reducer
• Single vs double ferrule · Tube fitting size chart
• Swagelok cross-reference · Request a quote