High-Pressure Cone-and-Thread (MP/HP) Fittings
A cone-and-thread fitting is a high-pressure tube connection in which the tube end is machined to a cone and an external left-hand thread, then sealed metal-to-metal by a gland (nut) and collar (sleeve) drawn into a matching cone seat. Crestflo builds coned-and-threaded medium-pressure (MP) and high-pressure (HP) fittings rated for working pressure up to 30,000 psi, or roughly 2,068 bar (206.8 MPa); that's the same 30,000 PSI rating quoted throughout the industry. They come in high-tensile 316/316L stainless and a full range of nickel and corrosion-resistant alloys. Each one is PED compliant, stamped with a heat/lot number, and shipped with an EN 10204 MTC 3.1 certificate as standard.
Standard items sit ready in stock; anything outside that range is made to order, with delivery running 6-8 weeks.
On this page, cone and thread refers specifically to the high-pressure fluid-connection method: a coned, externally threaded tube sealed by a gland and collar, used in autoclave, waterjet, oil-and-gas and hydrogen service. It does not mean a woodworking or lathe cone tool, a thread-cutting machine, or a plumbing thread cone.
Cone-and-Thread Fittings Are Also Known as MP/HP, Gland-and-Collar & Autoclave-Style Fittings
The same connection goes by several names. You'll see it written as a cone and thread fitting, cone & thread fitting, coned-and-threaded fitting, or coned-and-threaded connection. By pressure class, it's called the medium-pressure (MP) fitting, high-pressure (HP) fitting, MP/HP fitting, or, for the very-high-pressure version, the HHP fitting. The seal comes from a gland nut and a collar, so people also call it a gland-and-collar fitting. And because the method first caught on with autoclave and pressure-vessel test rigs, it's often known simply as an autoclave fitting or autoclave-style fitting. Engineers will just as often ask for a high-pressure threaded fitting or high-pressure tube fitting. Word order shifts too. "High pressure fittings, cone and thread" or "thread and cone fittings", both point to the same hardware described here.
How a Cone-and-Thread Connection Seals: Coned Tube, Left-Hand Thread, Gland & Collar
The joint is metal-to-metal and carries no elastomer in the primary high-pressure seal. Four elements make it work: the coned tube end, the external left-hand thread cut behind the cone, the gland (nut) that engages that thread, and the collar (sleeve), supplied as an anti-vibration collar where line vibration is a concern, that the gland drives forward. As the gland is tightened, it pushes the collar against the cone and seats the cone into the fitting's female cone seat, forming a leak-tight metal seal that a compression ferrule cannot hold at these pressures. The coned geometry and thread form follow the applicable MP or HP coned-and-threaded standard for the series: the tube is cut with an industry-standard included cone angle, commonly about a 59°–60° cone for MP/HP per the applicable standard, and MP and HP use different cone angles and thread sizes, all customizable to requirement. The tube is prepared by coning and threading it with the matching tooling before assembly; the connection is reusable, and unlike a compression fitting it has a collar rather than a ferrule. NPT ends per ASME B1.20.1 and adapter connections are supplied where rated.
Medium-Pressure (MP) vs High-Pressure (HP) Cone-and-Thread Series
Both series rely on the same coned-and-threaded, gland-and-collar method. What separates them is the pressure band and the tube geometry behind it. Medium-pressure connections cover the lower band; high-pressure connections take the higher one, and each comes with its own coned geometry and thread size. The table lays out the classes and ties each one to the neighboring Crestflo pressure tier. Conversions are exact-rounded industry values. Crestflo's coned-and-threaded fittings are rated up to 30,000 psi, while higher very-high-pressure (HHP) classes get handled on the 60,000 psi tier page.
| Coned-and-threaded class | Working pressure | bar / MPa | Typical service | Tier page |
|---|---|---|---|---|
| Low / medium pressure (LP–MP) | to 15,000 psi | 1,034 bar / 103.4 MPa | Instrument, hydraulic and test-rig lines | 15,000 psi tier |
| Medium pressure (MP) | to 20,000 psi | 1,379 bar / 137.9 MPa | High-pressure hydraulics, chemical injection, sampling | 20,000 psi tier |
| High pressure (HP) | to 30,000 psi | 2,068 bar / 206.8 MPa | Waterjet, subsea, research and high-pressure gas | This page (Crestflo cone-and-thread) |
| Very high pressure (HHP) | to 60,000 psi | 4,137 bar / 413.7 MPa | Ultra-high-pressure intensifier and research service | 60,000 psi tier |
For lower ratings that rely on compression tube fittings instead of coned-and-threaded joints, check out the 3,000 psi, 6,000 psi and 10,000 psi tiers. Crestflo also offers the full high-pressure fittings & valves range if you'd rather browse everything at once.
Cone-and-Thread Fitting Types: Adapters, Elbows, Tees, Crosses, Glands, Collars & Plugs
The coned-and-threaded family spans every flow-path shape we make. Each one comes with cone-and-thread ends, cone-and-thread by NPT, or adapter ends, so the connection can be matched to the build at hand. Ordering codes and series schemes differ by shape and are specific to each build. Need to match a shape to a series? Just ask our engineering team for the ordering-code guide.
| Shape | Description | Typical end options |
|---|---|---|
| Adapter (male/female) | Connects cone-and-thread to NPT, other threads or a second cone-and-thread end | Cone-and-thread × NPT / cone-and-thread |
| Straight & reducing couplings | Joins two runs of equal or stepped tube size | Cone-and-thread both ends |
| Elbow (90°) | Changes run direction | Cone-and-thread |
| Tee & cross | Branches a line into three or four ports | Cone-and-thread |
| Nipple | Short male-to-male extension between components | Cone-and-thread / NPT |
| Gland (nut) & collar (sleeve) | The connection components that seal the coned tube | Series-matched |
| Plug & cap | Isolate or close a port | Cone-and-thread |
| Bulkhead | Passes a line through a panel or wall | Cone-and-thread |
| Reducer | Steps between two tube sizes within the class | Cone-and-thread |
Cone-and-Thread Pressure Ratings & Sizes: to 30,000 PSI (2,068 bar), 1/16″–9/16″
Crestflo coned-and-threaded fittings carry a cold working pressure rating up to 30,000 psi (about 2,068 bar / 206.8 MPa). The certified rating for any given size, series and alloy gets confirmed on the RFQ. The class runs on standard MP and HP line sizes, commonly 1/16″, 1/8″, 1/4″, 3/8″ and 9/16″, plus their metric equivalents. Tube outside diameter and wall thickness follow the applicable coned-and-threaded standard and can be customized to requirement.
The seal is all-metal, so temperature limits come down to the alloy you choose rather than any seal material. Pressure-temperature values are applied per the relevant standard and confirmed by alloy on request. Both imperial and metric sizes are available.
| Attribute | Value | Basis |
|---|---|---|
| Working pressure | Up to 30,000 psi (2,068 bar / 206.8 MPa) | Crestflo cone-and-thread range |
| Connection method | Coned-and-threaded, gland-and-collar, metal-to-metal | Applicable coned-and-threaded standard |
| Thread | External left-hand thread on the coned tube | Applicable coned-and-threaded standard |
| Standard line sizes | 1/16″, 1/8″, 1/4″, 3/8″, 9/16″ (and metric) | Values per applicable standard; customizable to requirement |
| End options | Cone-and-thread, cone-and-thread × NPT (B1.20.1), adapters | ASME B1.20.1 for NPT ends |
| Temperature | Governed by alloy; per applicable standard | Confirmed per alloy on request |
Cone-and-Thread Fitting Materials: 316, Super Duplex 2507, Inconel 625, Monel & Hastelloy
Crestflo supplies stainless steel high-pressure fittings in high-tensile 316/316L, along with duplex, super-austenitic and nickel-alloy grades. Every one is machined from bar stock to ASTM A479 / A276. No brass.
Below, each grade links to its own material page. These fittings come in instrumentation form only; they aren't offered as bar, sheet or mill product. UNS designations follow the standard published values.
| Family | Grade (UNS) | When to choose | NACE option |
|---|---|---|---|
| Stainless | 316/316L (S31600/S31603), 904L (N08904) | General high-pressure hydraulic, test-rig and instrument service; 904L for higher chloride resistance | Yes |
| Duplex / super-austenitic | Super Duplex 2507 (S32750), 254 SMO (S31254), AL-6XN (N08367), Alloy 20 (N08020) | High-chloride, offshore and subsea high-pressure service needing strength plus pitting resistance | Yes |
| Nickel | Inconel 625 (N06625), Inconel 718 (N07718), Inconel 825 (N08825), Monel 400 (N04400), Hastelloy C-276 (N10276) | Sour, halide and reducing-acid high-pressure service; Inconel 718 for high-strength builds | Yes |
| Titanium | Titanium Gr2 (R50400) | Seawater and oxidizing-chloride high-pressure service | — |
For sour and H2S service, the material meets NACE MR0175 / ISO 15156. Finishes run the gamut: material finish, electropolish, passivation and silver anti-galling plating. All customizable to your requirements. Browse Crestflo's full line of instrumentation fitting and valve materials.
Standards, Testing & Traceability: ASTM F1387, NACE MR0175 & MTC 3.1
Crestflo is ISO 9001, ISO 14001, ISO 45001 and PED certified. Approvals follow the product type: coned-and-threaded and compression fittings are performance-qualified to ASTM F1387, and high-pressure material is supplied to NACE MR0175 / ISO 15156 for sour service. Where a coned-and-threaded valve accompanies the run, the valve qualifies to ASME B16.34 and the applicable API testing standards, not to F1387. Bar stock conforms to ASTM A479/A276 and tube to ASTM A269 / A213 where supplied.
Every part carries a heat/lot number marked directly on it. It ships as standard with an EN 10204 MTC 3.1 certificate, and MTC 3.2 with third-party endorsement is available on request. Crestflo keeps certificates in its quality system, so content pages state conformance rather than certificate numbers. Testing covers hydraulic proof, burst and impulse testing, pneumatic testing, flexure fatigue, vibration, thermal cycling, pull-out and vacuum testing, and positive material identification (PMI). Non-destructive testing happens in-house. Destructive testing goes out to ISO/IEC 17025-accredited laboratories. Third-party inspection can be arranged on request. See our testing & inspection and material traceability capabilities for more detail.
Autoclave-Style Interchange: Autoclave Engineers®, Parker Autoclave®, Butech® & HiP® Equivalents
Crestflo coned-and-threaded fittings are built for dimensional interchange with the established autoclave-style MP/HP lines. That means a high-pressure joint can be swapped out without redesigning the whole run. Autoclave Engineers®, Parker Autoclave®, Butech® and HiP® (High Pressure Equipment Company) are trademarks of their respective owners, and Crestflo isn't affiliated with, sponsored by, or endorsed by any of those companies. Parts are described as interchange or equivalent, never as "compatible" or "intermix." Every fitting carries ASTM F1387 performance qualification. Instead of publishing a part-number table, request your cross-reference, and our engineering team will map your existing autoclave, Butech, or MP/HP part to the Crestflo equivalent.
Cone-and-Thread Fitting Applications: Oil & Gas, Subsea, Hydrogen & Waterjet
You'll find coned-and-threaded fittings anywhere a small-bore line has to hold high pressure while keeping full material traceability. Think oil and gas upstream and production work, offshore and subsea systems, hydrogen generation and fueling, waterjet-cutting intensifier lines, chemical injection, hydraulics and high-pressure test rigs, and aerospace and defense test stands. A wide range, but the demand is the same everywhere: strength, and a paper trail on the material.
The connection pairs with high-pressure hydraulic tubing. It also pairs with Crestflo's high-pressure valves and fittings, built on that same coned-and-threaded body.
Why Buy Cone-and-Thread Fittings from Crestflo: a US High-Pressure Fittings Manufacturer
Crestflo makes high-pressure fittings for US customers. It's the instrumentation arm of an export house that's been around for four decades, carries Government of India recognition, and has a solid track record delivering into the Middle East, real heritage sitting behind a newly focused manufacturing brand. For US buyers who need high-pressure coned-and-threaded hardware, here's the offer, plain and simple:
- Coned-and-threaded fittings rated to 30,000 psi. Crestflo stocks the MP and HP series from a single supply base, and every fitting carries ASTM F1387 performance qualification, so that 30,000 PSI rating holds across the line.
- Ready stock for standard items, made-to-order for specials, and 6-8 week delivery. That's a sharp contrast to the 20-week-plus lead times common among the majors.
- Full alloy breadth, from 316L through Super Duplex, Inconel, Monel and Hastelloy. This range covers high-pressure corrosive and sour service that the autoclave-style majors tend to under-serve.
- Small MOQ and private-label programs for OEMs and distributors, with kitting to print.
- ISO 9001 / 14001 / 45001 and PED certified, MTC 3.1 and heat-number traceability on every part.
- Material is Indian origin, though US or European melt is available on request, backed by full material traceability, for TAA/DFARS-driven projects. Crestflo covers this on our US origin & compliance page.
At Crestflo, we engineer confidence. Ready to move forward? Request a quote, request a sample, or become a distributor. For US sales, reach us at sales@crestflousa.com or +1 346 594 9005. We're based in Houston, TX.
Cone-and-Thread Fittings FAQs
What is a cone-and-thread fitting?
A cone-and-thread fitting is a high-pressure connection: the tube end gets machined into a cone with an external left-hand thread, then a gland (nut) and collar (sleeve) draw it into a matching cone seat, sealing it metal-to-metal. Some call it an MP/HP fitting, others a gland-and-collar or autoclave-style fitting. Whatever the name, it holds pressures a compression ferrule simply can't.
What pressure can cone-and-thread fittings handle?
Crestflo coned-and-threaded fittings are rated for a working pressure up to 30,000 psi, roughly 2,068 bar or 206.8 MPa, in high-tensile stainless steel. That represents the standard 30,000 PSI class. Very-high-pressure (HHP) classes reaching 60,000 psi are covered on our 60,000 psi tier page. The certified rating for any particular size, series and alloy is always confirmed on the RFQ.
What is the difference between MP and HP fittings?
Both rely on the same coned-and-threaded, gland-and-collar approach. MP, the medium-pressure series, handles the lower band, commonly up to around 20,000 psi. HP, the high-pressure series, takes on the higher end, reaching 30,000 psi (30,000 PSI) in Crestflo's lineup. Thread sizes, coned geometries and tube walls differ between the two, so the working pressure of the line determines which class gets selected.
Are cone-and-thread fittings left-hand thread?
Yeah, the tube's external thread is usually left-hand. The gland catches that thread, and as you tighten it, it pushes the collar forward, seating the cone into the fitting's female cone seat.
How is a cone-and-thread fitting different from a compression (ferrule) fitting?
Compression fittings seal with ferrules, and the tube itself needs no modification. Cone-and-thread fittings work differently: the tube has to be coned and threaded before it's installed, and the seal comes from a gland and collar, not a ferrule. That coned metal-to-metal joint holds up under far higher pressure. Crestflo covers the ferrule style on our compression tube fittings page, and you'll find the full breakdown in the cone-and-thread vs compression comparison.
What materials are cone-and-thread fittings available in?
The lineup runs from high-tensile 316/316L and 904L stainless up through Super Duplex 2507, 254 SMO, AL-6XN and Alloy 20. For higher-demand applications there's Inconel 625/718/825, Monel 400 and Hastelloy C-276, plus Titanium Gr2. Silver anti-galling plating is available as an option. Brass isn't offered. The grade chosen depends on the media, the temperature, and whether chloride or H2S exposure is a factor.
Are cone-and-thread fittings NACE / sour-service compliant?
Yes. NACE MR0175 / ISO 15156-compliant material options are available for sour and H2S service, offered in the appropriate corrosion-resistant alloys. Each order ships with heat-number marking and an EN 10204 MTC 3.1 certificate, with 3.2 available on request.
Do you offer interchange with Autoclave Engineers, Parker or Butech fittings?
Crestflo coned-and-threaded fittings are engineered for dimensional interchange with the autoclave-style MP/HP lines and, for fittings, performance-qualified to ASTM F1387. Autoclave Engineers®, Parker Autoclave®, Butech® and HiP® are trademarks of their respective owners; Crestflo is not affiliated with them, and parts are interchange/equivalent rather than "compatible." Request your cross-reference from our engineering team.
Do cone-and-thread fittings use NPT threads?
Coned-and-threaded joints aren't the same method as NPT. Still, fittings are often supplied with NPT (ASME B1.20.1) end and adapter connections where rated, so a coned-and-threaded run can transition into an NPT port.
What temperature can cone-and-thread fittings handle?
Because the seal is all-metal and has no elastomer, the alloy chosen determines the temperature limit, not the seal material. The pressure-temperature basis follows the applicable standard, and it's confirmed per alloy on the RFQ.
Are cone-and-thread fittings made in the USA?
Crestflo manufactures high-pressure fittings for customers across the US. Standard stock comes from India. Need US or European melt instead? It's available on request, and we provide full material traceability whenever domestic-melt or TAA compliance is required. Expect delivery in 6-8 weeks. For details, visit our US origin & compliance page.
What is the lead time on cone-and-thread fittings?
Standard items ship from ready stock. Specials are made to order, with delivery in 6 to 8 weeks. That's well under the 20-week-plus lead times typical of the major suppliers. Small MOQs are available, and so is private label.
Related Pages
- High-pressure fittings & valves range
- Pressure ratings run in three tiers: 15,000 psi, 20,000 psi, and 60,000 psi.
- Not sure which fitting style fits your line? Start with cone-and-thread vs compression fittings, then browse compression tube fittings directly.
- On the tubing side, Crestflo covers high-pressure hydraulic tubing and the matching high-pressure valves.
- For standards, there's ASTM F1387 interchange qualification and NACE MR0175. F1387 and MR0175 both turn up often in these product specs.
- If you're sourcing out of Texas, Crestflo shows up as a cone-and-thread fittings supplier and a high-pressure fittings supplier right in the state.