Hy-Lok vs Crestflo: Instrumentation Tube Fitting & Valve Comparison
This comparison sets Hy-Lok against Crestflo, two twin-ferrule instrumentation systems worth weighing side by side. Hy-Lok is a South Korean manufacturer that makes double-ferrule compression tube fittings and instrumentation valves. Crestflo serves the US market, and its twin-ferrule fittings are qualified for dimensional interchange under ASTM F1387 performance testing. Both companies work within the same mechanical design space. What separates them comes down to alloy depth, certification and traceability documentation, lead time, and how each sources its products. The focus here stays narrow: instrumentation tube fittings, meaning twin-ferrule (double-ferrule) compression fittings, along with instrumentation valves in stainless and high-nickel/CRA alloys. Electrical wire ferrules and copper plumbing compression fittings aren't part of it.
Hy-Lok® is a trademark held by Hy-Lok Corporation. Crestflo isn't affiliated with, sponsored by, or endorsed by that company, and it doesn't hold a license from them either. The comparisons here are strictly dimensional, meant only as a reference for interchange.
Also Known As: Hy-Lok, HyLok, Hy Lok, Hy-Lok USA & Hy-Lok Canada
People land on this comparison after typing the brand a dozen different ways. Some write Hy-Lok, others HyLok, Hy Lok, or hylok, and the name attaches to Hy-Lok Corporation (also styled Hy-Lok Inc.), Hy-Lok USA, and Hy-Lok Canada. The product line gets described just as inconsistently: Hy-Lok tube fittings, Hy-Lok twin-ferrule fittings (sometimes called two-ferrule or double-ferrule), Hy-Lok compression fittings, and Hy-Lok instrumentation valves, all sold through a network of Hy-Lok distributors and suppliers. Flip the order and you land on Crestflo vs Hy-Lok, the same comparison asked the other way.
Who Is Hy-Lok? Hy-Lok Corporation, Hy-Lok Korea & Twin-Ferrule Fittings
Hy-Lok Corporation makes instrumentation fittings and valves, and it's headquartered in Busan, South Korea. The company reaches the North American market through Hy-Lok USA and Hy-Lok Canada. At the core of the Hy-Lok line sit twin-ferrule, double-ferrule compression tube fittings, alongside a wide range of instrumentation valves in ball, needle, check, and manifold types. These are built to be dimensionally interchangeable with the standard double-ferrule pattern. Sizes run fractional and metric. Thread ends cover NPT, BSPT, BSPP, and ISO-parallel, and that applies across the tube fittings, ball valves, and needle valves listed in the catalog. Hy-Lok® is a trademark of Hy-Lok Corporation. Nothing above is promotional; it's simply a factual description.
Hy-Lok vs Crestflo: Full Comparison Table
Crestflo's numbers come straight from Crestflo product data and the applicable standards. That's not the case for Hy-Lok's figures, which reflect the manufacturer's own published positioning. Confirm any Hy-Lok figure against Hy-Lok's current published data before you specify. Reviews of Hy-Lok and buyer discussion of it tend to surface in manufacturer catalogs, distributor line cards, and engineering forums such as Reddit's tube-fitting threads, not in neutral spec comparisons. The side-by-side below fills that gap, covering the attributes that actually decide a specification.
| Attribute | Hy-Lok | Crestflo |
|---|---|---|
| Brand / origin | Hy-Lok Corporation, Busan, South Korea; served via Hy-Lok USA and Hy-Lok Canada | Crestflo, US-serving manufacturer; Indian origin, US/European melt available on request |
| Core fitting design | Twin-ferrule (double-ferrule) compression tube fitting | Twin-ferrule and single-ferrule compression tube fittings; hardened & non-hardened ferrules |
| Interchange basis (fittings) | Marketed as dimensionally interchangeable with the double-ferrule pattern | Dimensional interchange qualified under ASTM F1387 performance testing |
| Valve qualification basis | Manufacturer QA program | Instrumentation valves built to ASME B16.34 / API 6D / 598 / 602 as applicable |
| Size range | Fractional and metric, per published catalog | End connections up to 2" (50 mm) OD; imperial and metric on all fittings |
| Working pressure / pressure rating | Product-dependent; per series and material | Fitting pressure rating per the ASTM F1387 test basis and tube schedule; manifolds to 10,000 psi; cone-and-thread line to 30,000 psi, working pressure per applicable standard, customizable to requirement |
| Stainless grades | 316/316L primary | 304/304L, 316/316L, 904L |
| Exotic / CRA alloys | Select alloys per line; confirm with manufacturer | Duplex 2205, Super Duplex 2507, 254 SMO, AL-6XN, Alloy 20; Inconel 600/601/625/718/825, Monel 400/K500, Hastelloy C-276/C-22/B-2/B-3/X, Incoloy 800/825, Nickel 200/201, Titanium Gr2 |
| Instrumentation valves | Ball, needle, check, and manifold valves | Ball, needle, check, bellows/diaphragm (packless), relief, bleed, metering, manifold (2/3/5-way), DBB, gauge, toggle, plug, 1/16"–1" |
| NACE / sour service | Available on select materials | NACE MR0175 / ISO 15156-compliant materials |
| Certifications | ISO 9001; product approvals per Hy-Lok | ISO 9001 / 14001 / 45001 & PED certified; ASTM F1387 (fittings) |
| Traceability / MTC | Material certificates available | EN 10204 MTC 3.1 standard, 3.2 on request; heat/lot number on every part |
| Thread / end options | NPT, BSPT, BSPP, ISO-parallel, tube/weld ends | NPT (B1.20.1), national/international/custom threads; socket/butt-weld; 37° flare (ISO 8434-2) |
| Lead time | Via distributor stock / factory | Ready stock for standard items · made-to-order for specials · 6–8 week delivery |
| MOQ / private label | Distributor-driven | Small MOQ; private-label / OEM program available |
Twin-Ferrule Design: How Hy-Lok & Crestflo Fittings Line Up
Crestflo builds this fitting envelope in two forms: twin-ferrule (double-ferrule) and single-ferrule, with hardened and non-hardened ferrules available to requirement. Both systems rely on a two-piece ferrule set, a front ferrule that seals against the fitting body and tube, and a back ferrule that grips the tube, driven forward by nut advancement to form a mechanical, gas-tight compression joint. The nut thread, ferrule geometry, and gauging window all match the standard instrumentation pattern. For the details, see the single vs double ferrule explainer and the tube fitting ferrules page.
Interchange here means dimensional interchange, not parts-swapping. Replace the complete fitting. Stick to single-brand practice within one connection, and don't mix ferrules from different brands in the same joint.
Interchange & Dimensional Equivalence: The ASTM F1387 Basis
Interchange between Hy-Lok and Crestflo tube fittings comes down to dimensions, not a claim that the two brands share a manufacturer. Crestflo twin-ferrule fittings are engineered so the front-ferrule and back-ferrule geometry, the nut thread, and the gauging envelope all match the standard instrumentation double-ferrule pattern. That match isn't just asserted on paper; it's backed by ASTM F1387 interchange qualification performance testing, not a dimensional claim alone. Few competitors offer evidence this credible or this well documented. The relationship remains a dimensional interchange: equivalent geometry proven through performance testing, not a shared-manufacture or licensed-replacement part. Crestflo won't publish an unverified Hy-Lok-to-Crestflo part number. Instead, request your Hy-Lok cross-reference, and the engineering team will confirm the equivalent against your exact Hy-Lok part before you place an order. For more detail, check the master interchange overview and the switch-source case described on the Hy-Lok alternative page.
Size & Thread Parity: Imperial, Metric, NPT & BSP
Crestflo matches the size and thread range of the major twin-ferrule brands. End connections run up to 2" (50 mm) OD, available in both imperial and metric sizing. Thread options include NPT (per ASME B1.20.1), BSPT, BSPP, and ISO-parallel, plus socket-weld and butt-weld ends and 37° flare per ISO 8434-2.
Fractional sizes such as 1/4", 3/8", and 1/2" are all supported. So are metric sizes like 6 mm, 10 mm, and 12 mm. A Hy-Lok size and thread call-out maps straight across to a Crestflo equivalent.
Dimensions follow the applicable ASME/ISO thread and OD standards, and everything's customizable to requirement.
Alloys: 316 Stainless to Exotic CRA (Duplex, Inconel, Hastelloy, Titanium)
Hy-Lok sticks to mainstream 316/316L stainless. Crestflo doesn't stop there: it carries the same stainless line, plus a deep range of corrosion-resistant alloys for sour, chloride, and high-temperature service. All of it comes in instrumentation forms, including twin-ferrule tube fittings and valves, backed by heat-number traceability.
| Alloy family | Grades (UNS) | Instrumentation forms |
|---|---|---|
| Austenitic stainless | 304/304L, 316/316L (S30400/S31600), 904L (N08904) | Fittings, valves, tubing |
| Duplex / super-duplex | 2205 (S32205), 2507 (S32750) | Fittings, valves, tubing |
| Super-austenitic | 254 SMO (S31254), AL-6XN (N08367), Alloy 20 (N08020) | Fittings, valves, tubing |
| Nickel | Inconel 625/825, Monel 400/K500, Hastelloy C-276/C-22 | Fittings, valves, tubing |
| Titanium | Grade 2 (R50400) | Fittings, valves, tubing |
Compositions follow the applicable ASTM/UNS specifications, and they're customizable to requirement. For sour service, grades meeting NACE MR0175 / ISO 15156 are available.
Valves: Hy-Lok vs Crestflo Ball, Needle, Manifold & DBB
Both brands compete in the instrumentation valve space. Crestflo's instrumentation valves run from 1/16" to 1", in metric or imperial, with threaded or tube-fitting ends. Fittings get qualified to ASTM F1387; valves don't work that way. Each valve type is built to the standard that actually applies to it. These aren't plumbing or automotive parts. They're fluid-system instrumentation valves, meant for analytical, process-instrument, hydraulic, and gas-panel service.
| Valve type | Size range | Standard basis | Product |
|---|---|---|---|
| Ball valve | 1/16"–1" | Manufacturer QA / API 6D as applicable | Ball valve |
| Needle valve | 1/16"–1" | Manufacturer QA / API 602 as applicable | Needle valve |
| Manifold (2/3/5-way) | To 10,000 psi | 100% seat & shell leak tested | Instrumentation valves |
| Double block & bleed | Per design | ASME B16.34 | ASME B16.34 |
Pressure and temperature ratings follow the applicable standard and valve series. They can be adjusted to suit specific requirements.
Lead Time & Total Cost After US Duties
Crestflo ships standard items straight from ready stock. Specials go out on a 6-8 week made-to-order schedule, a sharp contrast to the 20-plus-week lead times that come standard with engineered instrumentation from the major manufacturers. Once US duties are factored in, the delivered cost doesn't lose its edge, and small-MOQ and private-label programs do away with the distributor-stock minimums that so often trip up buyers on brand-name lines. For the numbers behind this, see the tube fitting lead time capability and the post-tariff cost benchmark.
Certifications, Traceability & Testing
Crestflo holds ISO 9001, 14001, 45001, and PED certification. Its compression fittings meet ASTM F1387, and sour-service materials satisfy NACE MR0175 / ISO 15156. Every part gets stamped with a heat and lot number. EN 10204 MTC 3.1 comes standard, with 3.2 available on request. In-house teams handle NDT, PMI, and destructive testing at labs accredited to ISO/IEC 17025, and third-party inspection can be arranged when needed. Certificates stay on file; see material traceability. Datasheets and CAD files aren't posted publicly, but customers can request them directly.
How Hy-Lok Compares to Other Twin-Ferrule Brands: Swagelok, Parker, DK-Lok, Fitok & Superlok
Hy-Lok competes in a crowded field of twin-ferrule instrumentation brands. Buyers weighing it usually run the parallel comparisons before they settle a specification: Hy-Lok vs Swagelok, Hy-Lok vs Parker, Hy-Lok vs DK-Lok, Hy-Lok vs Fitok, and Hy-Lok vs Superlok. Each of these lines builds the same double-ferrule mechanical-grip pattern. So the deciding factors are alloy depth, certification, traceability, lead time, and cost, not the base geometry. Crestflo qualifies its interchange against each of them on the same ASTM F1387 performance basis.
Compare the neighboring lines directly on the Swagelok vs Crestflo, Parker A-Lok vs Crestflo, Fitok vs Crestflo, DK-Lok vs Crestflo, Hoke vs Crestflo, and Ham-Let vs Crestflo pages. Or open the master interchange overview for the full brand set.
Why Crestflo
Crestflo is the instrumentation division of an export house with four decades behind it, one recognized by the Government of India and with an established delivery record across the Middle East. That heritage backs the quality system behind a new manufacturing brand. Set against Hy-Lok, the differences are concrete: ASTM F1387-qualified dimensional interchange, a far wider range of exotic alloys, delivery in 6 to 8 weeks, small MOQ with private label, and heat-number traceability with MTC 3.1/3.2 on every single part. Origin is stated plainly: Indian origin, with US or European melt available on request, and full material traceability. TAA and DFARS options are laid out at US-origin compliance. We Engineer Confidence.
Request a Quote, Sample or Cross-Reference
Want to see how Crestflo measures up against a Hy-Lok spec? Start here: request a quote for Hy-Lok-equivalent fittings, request a sample, or look over the distributor and OEM program. Houston-based, the US team is reachable at sales@crestflousa.com or +1 346 594 9005. For related lines, check the Swagelok vs Crestflo, Parker A-Lok vs Crestflo, and Fitok vs Crestflo pages, or head back to the cross-reference hub.
Frequently Asked Questions: Hy-Lok vs Crestflo
Is Crestflo a drop-in interchange for Hy-Lok fittings?
Crestflo twin-ferrule fittings match the standard instrumentation double-ferrule pattern dimension for dimension, and they've been qualified under ASTM F1387 performance testing. Unverified equivalents never make it into Crestflo's catalog. Ask for your Hy-Lok cross-reference, and the engineering team will confirm the fit against your exact Hy-Lok part before you order.
Are Hy-Lok and Crestflo fittings interchangeable?
Under ASTM F1387 performance qualification, they're dimensionally equivalent. Stick to single-brand practice within one connection: replace the complete fitting rather than mixing ferrules from different brands in the same joint. Specify your Hy-Lok size and thread on the RFQ, and you'll get a confirmed equivalent back.
Are Hy-Lok and Swagelok interchangeable?
Hy-Lok sells its twin-ferrule fittings as dimensionally interchangeable with the standard double-ferrule pattern Swagelok established. In practice, a fitting body from one brand will thread and gauge to the matching size of the other. But the right engineering term here is dimensional interchange, not "compatible" and not "intermix." Stick to single-brand practice within any one connection: replace the whole fitting, and don't mix ferrules from two brands in the same joint. Crestflo holds the same position, backed by ASTM F1387 performance testing. Specify your Hy-Lok size and thread on the RFQ, and you'll get a confirmed equivalent.
Is Crestflo affiliated with Hy-Lok?
No. Hy-Lok® is a registered trademark of Hy-Lok Corporation. Crestflo is a separate, independent manufacturer, and it isn't affiliated with, sponsored by, endorsed by, or a licensee of that company. Any reference to Hy-Lok in this document exists strictly to compare dimensions for interchange.
Who makes Hy-Lok, and where?
Hy-Lok Corporation's headquarters sits in Busan, South Korea. It serves the North American market through two arms: Hy-Lok USA and Hy-Lok Canada. The company builds twin-ferrule instrumentation tube fittings, plus a range of instrumentation valves.
What is the Hy-Lok to Crestflo part-number cross-reference?
Crestflo won't publish an unchecked chart. Instead, it confirms verified equivalents on request. Submit your cross-reference through the Hy-Lok cross-reference page, and the engineering team will send back the confirmed Crestflo equivalent for your Hy-Lok part number.
What alloys does Crestflo offer that Hy-Lok may not stock?
Nickel 200/201, and Titanium Grade 2 fittings and valves round out what Crestflo carries alongside its 304/316/904L stainless lines, plus Duplex 2205, Super Duplex 2507, 254 SMO, AL-6XN, Alloy 20, Inconel, Monel, Hastelloy, and Incoloy in the 2 in instrumentation size range. That breadth gives buyers more corrosion-resistant-alloy options to pull from when a job calls for sour or chloride service.
What sizes and threads does Crestflo cover versus Hy-Lok?
It covers imperial and metric alike, with tube OD running up to 2" (50 mm). Thread options span NPT, BSPT, BSPP, and ISO-parallel, and end types include socket-weld, butt-weld, and 37° flare. That's what lets a Hy-Lok size and thread call-out map straight across to a Crestflo equivalent.
How does lead time compare to Hy-Lok and the majors?
Crestflo ships standard items straight from stock. Specials made to order take just 6 to 8 weeks. That's a sharp contrast to the 20-plus-week lead times typical of engineered instrumentation from major brands.
Are Crestflo valves interchangeable with Hy-Lok valves?
Crestflo makes matching instrumentation ball, needle, check, and manifold valves, matched in size and end configuration. They're built to the valve standards that actually apply: ASME B16.34 and API 6D/598/602, not the fitting-only ASTM F1387. Confirm your model on the RFQ.
Are Crestflo fittings NACE compliant for sour service?
Yes. Crestflo supplies NACE MR0175 / ISO 15156-compliant materials, backed by EN 10204 MTC 3.1 or 3.2 certification. Every part carries heat-number traceability, in line with ISO 15156.
Where are Crestflo parts made?
Crestflo is a US-serving manufacturer of Indian origin. US or European melt is available on request, and full material traceability comes standard. Origin details and TAA/DFARS options are stated honestly on the US-origin compliance page.
Can I get private-label or small quantities?
Yes. We offer small-MOQ programs as well as private-label and OEM options. Start with a quote or a sample request, and the engineering team will scope the program to match your volumes.
Related Cross-References & Resources
- Hy-Lok cross-reference, request your part equivalent
- Hy-Lok alternative, switch-source guide
- Single vs double ferrule, design explainer
- Tube fitting ferrules, the double-ferrule set
- Cross-reference hub, all interchange pages
The Crestflo Engineering Team reviewed this piece. Hy-Lok® is a trademark owned by Hy-Lok Corporation. Crestflo has no affiliation with Hy-Lok Corporation, and it doesn't sponsor, endorse, or license this content.