DK-LOK® Tube Fitting & Valve Cross-Reference: Crestflo Interchange Equivalents in Stainless AND Exotic Alloys
> Trademark & independence notice: "DK-LOK®" is a registered trademark of DK-Lok Corporation. Crestflo is not affiliated with, authorized by, sponsored by, or endorsed by DK-Lok Corporation. Every reference on this page is nominative, used only to identify the parts you already run so you can find the dimensionally equivalent Crestflo part. All claims are factual and dimensional. Crestflo supplies independently manufactured equivalents, not genuine DK-LOK products.
Crestflo manufactures dimensional equivalents to DK-LOK® twin-ferrule tube fittings and instrumentation valves, instrumentation compression fittings whose interchange is qualified to ASTM F1387, with valves built to the applicable ASME B16.34 / API standards, in 316L stainless and exotic alloys including Hastelloy, Super Duplex, Inconel, and Monel, with 6–8 week delivery. Send us the DK-LOK part numbers you buy today and we return the interchange equivalent, the alloys it ships in, and a quote.
Request your DK-LOK cross-reference & quote → · Send a part list, a print, or a sample, the Crestflo Engineering Team identifies the equivalent for you.
Scope: this cross-reference is for instrumentation twin-ferrule tube fittings and instrumentation valves in stainless steel and alloy, not hydraulic/JIC, plumbing compression, or electrical ferrules. Here "ferrule" means a fluid-system compression ferrule, "ball valve" and "needle valve" mean instrumentation valves, and "manifold" means a valve manifold.
What DK-LOK tube fittings and valves are
DK-LOK® tube fittings are twin-ferrule (double-ferrule) instrumentation compression fittings that seal small-bore stainless and alloy tubing in analytical, process, and hydraulic instrument lines, and DK-LOK also builds a matching family of instrumentation valves. A complete twin-ferrule fitting is a body, a nut, a front ferrule, and a back ferrule; pulling the nut up advances the two ferrules onto the tube OD to make a gas-tight, mechanically gripped joint. DK-Lok Corporation is a twin-ferrule fitting and valve manufacturer based in Busan, South Korea, sold in North America through DK-LOK USA and DK-LOK Canada. Crestflo builds to the same twin-ferrule geometry and the same imperial and metric size conventions, which is what makes a location-for-location swap possible.
DK-LOK designations this cross-reference also covers
DK-LOK buyers write the brand and the interchange in many forms, and every one of them points to the same Crestflo interchange.
| Category | Terms & phrasings |
|---|---|
| Brand spellings | DK-LOK · DK-Lok · DK Lok · DKLOK · dk-lok · DK-LOK USA · DK-LOK Canada · DK-Lok Korea · DK-Lok Corporation (Busan, South Korea) |
| Interchange terms | DK-LOK cross reference · DK-LOK interchange · DK-LOK equivalent · DK-LOK replacement · DK-LOK crossover · DK-LOK part number cross reference · DK-LOK cross reference chart / conversion chart / PDF |
| Switch / price terms | DK-LOK alternative · DK-LOK fitting alternative · alternative to DK-LOK · DK-LOK distributor USA |
| "Fit" question terms | is DK-LOK interchangeable · DK-LOK vs Swagelok · Swagelok to DK-LOK cross reference · are DK-LOK and Swagelok interchangeable (answered as interchange, don't intermix) |
| Fitting types | twin ferrule · double ferrule · single ferrule · nut and ferrule · front ferrule · back ferrule · union · tee · elbow · connector · reducer · bulkhead union · cap · plug |
| Valve types | needle valve · ball valve · check valve · manifold valve (2/3/5-valve) · gauge / root valve · bleed valve · quick connect |
| Alloys | 316/316L · 904L · Duplex 2205 · Super Duplex 2507 · 254 SMO · Alloy 20 · Inconel 625/825 · Monel 400 · Hastelloy C-276/C-22 · Titanium Gr2 |
| Sizes / ends | imperial AND metric tube OD up to 2" (50 mm) · NPT · NPTF · BSPT · BSPP · ISO-parallel · JIC-37° · SAE-ORB · socket/butt-weld |
| Proof / standard | ASTM F1387 (fittings) · ASME B16.34 / API (valves) |
DK-LOK interchange attributes: how the equivalent is defined
A cross-reference answers one question: for the DK-LOK part I buy today, what is the Crestflo part that dimensionally interchanges, and in which alloys? Because part-number mapping must be verified against your exact series, size, and material rather than guessed, Crestflo builds your cross-reference to order rather than publishing a generic parts table. That keeps every equivalent accurate to your bill of materials.
DK-LOK-to-Crestflo interchange attribute set
| Attribute | Crestflo equivalent basis |
|---|---|
| Interchange basis (fittings) | Dimensional interchange qualified to ASTM F1387 |
| Valve qualification | Built to the applicable ASME B16.34 / API standards for the valve type |
| Ferrule design | Twin-ferrule (double-ferrule); single-ferrule available; hardened or non-hardened to requirement |
| Tube OD range | Up to 2" (50 mm) OD; imperial AND metric |
| End & thread options | Tube-OD, NPT (B1.20.1), NPTF, BSPT, BSPP, ISO-parallel, JIC-37°, SAE-ORB, socket-weld, butt-weld |
| Alloys | 316/316L standard; 904L, Duplex 2205, Super Duplex 2507, 254 SMO, Alloy 20, Inconel 625/825, Monel 400, Hastelloy C-276/C-22, Titanium Gr2 |
| Traceability | Heat/lot number on every part + EN 10204 3.1 MTC (3.2 on request) |
| Testing regime | Hydraulic proof/burst/impulse, pneumatic, flexure/rotary-flex fatigue, vibration, thermal cycling, pull-out, vacuum; PMI |
| Lead time | Ready stock for standard items · made-to-order for specials · 6–8 week delivery |
| Origin | Indian origin; US / European melt available on request, with full material traceability |
Values per applicable standard; customizable to requirement. Per-part alloy and size confirmation is provided with your quote.
DK-LOK part number cross reference: how to request it
Send us the DK-LOK part numbers, a line-card export, a drawing, or a physical sample. The Crestflo Engineering Team returns the interchange equivalent, the ferrule and connection parity notes, the available alloys, and a quote, no login, no gated tool.
Request your DK-LOK® cross-reference →
DK-LOK cross reference chart / PDF: what you get instead
Where competitors bury interchange data in gated tools or un-searchable PDFs, Crestflo returns your chart as a clean, verified document tied to your actual part list. Ask for it through the request-a-quote form or by emailing sales@crestflousa.com. You can also open the cross-reference lookup tool to start a request.
DK-LOK product families cross-referenced: fittings, ferrules & valves
Crestflo equals the DK-LOK instrumentation catalog family for family, each with its own product line to link to.
| DK-LOK family | Crestflo equivalent | Product page |
|---|---|---|
| Twin-ferrule / compression tube fittings | Twin-ferrule instrumentation tube fittings | Tube fittings |
| Single-ferrule fittings | Single-ferrule tube fittings | Single-ferrule |
| Ferrules & nut-and-ferrule sets | Complete nut & ferrule sets | Nut & ferrule · Ferrules |
| Needle valves | Instrumentation needle valves | Needle valve |
| Ball valves | Instrumentation ball valves | Ball valve |
| Check valves | Check valves / NRV | Check valve |
| Manifold valves (2/3/5-valve) | 2-, 3- and 5-valve manifolds | 3-valve manifold |
| Gauge / root & bleed valves | Gauge-root and bleed valves | Gauge-root valve · Bleed valve |
| Quick connects | Instrumentation quick-connects | Quick connects |
The full valve range, 1/16" to 1", threaded or tube-fitting ends, sits under instrumentation valves.
DK-LOK equivalents in stainless AND exotic alloys: the Crestflo wedge
This is where Crestflo separates from stainless-only cross-references: the same dimensionally equivalent fitting is available not just in 316 SS but across exotic and corrosion-resistant alloys that DK-LOK's stock range does not lead with. Availability is by fitting type and alloy; per-part confirmation comes with your quote.
Alloy-availability matrix, Crestflo DK-LOK-equivalent fittings
| Fitting / part type | 316/316L | 904L | Duplex 2205 | Super Duplex 2507 | 254 SMO | Alloy 20 | Inconel 625 | Inconel 825 | Monel 400 | Hastelloy C-276 | Titanium Gr2 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Union / reducing union | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Tee / cross | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Elbow | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Male / female connector | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Bulkhead union / port connector | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Cap / plug | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Nut & ferrule set | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Needle / ball / check valve | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
✓ = available / made-to-order in that alloy. Ready stock for standard items · made-to-order for specials · 6–8 week delivery.
DK-LOK fitting in Hastelloy C-276
For wet-chlorine, sulfuric, and mixed-acid service, Crestflo equals the DK-LOK part in Hastelloy C-276 / C-22. See Hastelloy C-276 tube fittings and the Hastelloy C-276 material page.
DK-LOK fitting in Super Duplex 2507 & Duplex 2205
For high-chloride and offshore seawater duty, the equivalent is available in Super Duplex 2507 and Duplex 2205. See Super Duplex 2507 tube fittings and the Duplex 2205 material page.
DK-LOK fitting in Inconel 625 / Inconel 825 & Monel 400
For high-temperature, sour-gas, and hydrofluoric service, Crestflo equals it in Inconel 625, Inconel 825, and Monel 400. See Inconel 625 tube fittings, Inconel 825 tube fittings, and Monel 400 tube fittings.
DK-LOK fitting in 254 SMO, Alloy 20 & 904L
For sulfuric-acid and high-chloride process lines, Crestflo also supplies the equivalent in 254 SMO, Alloy 20, and 904L, see the 254 SMO, Alloy 20, and 904L material pages. Default material is 316/316L, see the 316/316L material page.
Is DK-LOK interchangeable? Interchange vs. intermix
This is the question every specifying engineer should ask, and the honest answer earns trust:
- Interchange (correct): replace a complete DK-LOK fitting with a complete Crestflo fitting at the same location. Body, nut, and both ferrules are Crestflo. This is what "DK-LOK equivalent" and "drop-in replacement" mean here.
- Intermix (do not do this): mixing a Crestflo ferrule or nut with a DK-LOK body, or vice versa, inside a single joint. Twin-ferrule geometry and hardness are engineered as a set; mixing components across brands within one joint can compromise the seal and is not what "interchange" means.
DK-LOK and Swagelok are both twin-ferrule instrumentation systems built to comparable dimensional envelopes, which is why buyers ask whether they interchange. The precise, safe answer is the same for every brand: use complete fittings of one brand as interchange equivalents; validate the specific part; and do not intermix components across brands within a joint. Crestflo publishes F1387-qualified equivalents for both, see the Swagelok cross-reference and the master interchange chart. For the geometry itself, see single vs double ferrule. For a feature-by-feature comparison, see DK-LOK vs Crestflo; for the switching case, DK-LOK alternative.
Why the interchange is proven: ASTM F1387 for fittings, ASME B16.34 / API for valves
The interchange claim is not a marketing assertion, it rests on published standards. Crestflo compression tube fittings are qualified to ASTM F1387, the performance qualification for mechanically attached (compression tube) fittings, covering the dimensional and performance behavior that is the basis for equivalence. Instrumentation valves are a different entity: they are built to the applicable ASME B16.34 and API 6D / 598 / 602 valve standards for the type, not to F1387 (which applies to fittings). That distinction is exactly the kind of documented rigor that separates a qualified equivalent from an uncontrolled marketplace "equivalent" with no proof or traceability.
Interchange-proof summary
| Attribute | Basis |
|---|---|
| Fitting interchange | Dimensional interchange qualified to ASTM F1387 |
| Valve qualification | ASME B16.34 / API 6D / 598 / 602 as applicable |
| Ferrule geometry | Twin-ferrule (front + back); single & double; hardened or non-hardened |
| Size range | Up to 2" (50 mm) OD; imperial AND metric |
| Connections / threads | Tube-OD, NPT (B1.20.1), NPTF, BSPT, BSPP, ISO-parallel, JIC-37°, SAE-ORB, socket/butt-weld |
| Corrosion / sour service | NACE MR0175 / ISO 15156 compliant |
| Traceability | Heat/lot number on every part + EN 10204 3.1 MTC (3.2 on request) |
| Certification | ISO 9001 / 14001 / 45001 & PED certified |
Read more on the ASTM F1387 interchange qualification, the ASME B16.34 and NACE MR0175 standard pages, the EN 10204 MTC page, traceability, and testing & inspection.
How to request your DK-LOK cross-reference
- Send your DK-LOK part numbers, a line-card export, a drawing, or a sample.
- Tell us the alloy and size you need (or ask us to match what you run today).
- We return the Crestflo equivalent, alloy availability, and quote, typically for delivery in 6–8 weeks.
Buyer paths: distributors → line-card / stocking program · equipment manufacturers → send a print for made-to-print interchange · OEMs → private-label program · end users, MRO & EPC → RFQ or sample. All routes start at the RFQ form.
RFQ form fields: Name · Company name · Email · Phone · Requirement description.
Request your DK-LOK® cross-reference & quote → · Request a sample · Or contact Crestflo: sales@crestflousa.com · +1 346 594 9005 · Houston, TX.
Why buyers switch to Crestflo
Crestflo is the alloy-aware, standards-backed alternative to DK-LOK, and the reasons buyers move are specific:
- Drop-in interchange, dimensionally equal and qualified to ASTM F1387, not a marketplace guess.
- Stainless AND exotic alloys, Hastelloy, Super Duplex, Inconel, Monel, 254 SMO, Alloy 20, a range a stock catalog does not lead with.
- 6–8 week delivery on made-to-order specials, versus the long lead times common on the majors.
- Cost-competitive even after US duties/tariffs, see the tariff cost advantage.
- Small MOQ and private-label / OEM programs, with a stated lead time.
- Heat/lot number on every part with EN 10204 3.1 MTC as standard.
- ISO 9001 / 14001 / 45001 & PED certified.
Crestflo is the instrumentation division of a four-decade, Government-of-India-recognized export house with a Middle-East delivery track record, established manufacturing heritage behind a focused US-serving instrumentation brand. Origin: Indian origin; US / European melt available on request, with full material traceability, see US-origin compliance. We Engineer Confidence.
Explore the underlying product line: Crestflo tube fittings, nut & ferrule sets, and instrumentation valves.
FAQ
Are DK-LOK and Crestflo fittings interchangeable?
Yes, Crestflo twin-ferrule fittings are engineered to dimensionally interchange with DK-LOK® parts and are qualified to ASTM F1387. Use complete Crestflo fittings to replace complete DK-LOK fittings at a location, and validate the specific part for your service before mixing components across a joint.
Are DK-Lok parts compatible with Swagelok parts?
DK-LOK and Swagelok are both twin-ferrule instrumentation systems built to comparable dimensional envelopes, so interchange should be confirmed per part rather than assumed. Crestflo publishes F1387-qualified equivalents for both, see our Swagelok and master interchange charts. Use complete fittings of one brand; do not intermix components across brands within a single joint.
How do I find the Crestflo equivalent to a DK-LOK part number?
Send your DK-LOK part number, a BOM, a print, or a sample. The Crestflo Engineering Team returns the dimensionally interchanging Crestflo part, the alloys it is available in, and a quote, built to your actual list rather than a generic table.
Do you sell genuine DK-LOK parts?
No. Crestflo is an independent manufacturer of interchangeable equivalents and is not affiliated with, authorized by, or endorsed by DK-Lok Corporation. DK-LOK® is a registered trademark of DK-Lok Corporation.
Can I get a DK-LOK equivalent in Hastelloy, Super Duplex, or Inconel?
Yes, Crestflo supplies the equivalent in 316/316L and 904L stainless plus exotic alloys including Hastelloy C-276/C-22, Super Duplex 2507, 254 SMO, Alloy 20, Inconel 625/825, Monel 400, and Titanium Gr2, a range stock cross-references don't offer.
What proves the interchange will seal?
For fittings, ASTM F1387 performance qualification (covering proof, burst, impulse, vibration, and pull-out behavior), plus PMI, NDT, and heat-number traceability with EN 10204 3.1 / 3.2 MTC. Instrumentation valves are built to the applicable ASME B16.34 / API standards for the type.
Do you cross-reference DK-LOK valves as well as fittings?
Yes, needle, ball, check, manifold (2/3/5-valve), gauge-root, and bleed valves, plus quick-connects. Valves are qualified to the applicable ASME B16.34 / API standard rather than ASTM F1387, which applies to compression tube fittings.
Are metric and imperial sizes both available?
Yes, both imperial (fractional) and metric on all fittings, in tube OD up to 2" (50 mm), with NPT, NPTF, BSPT, BSPP, ISO-parallel, JIC-37°, SAE-ORB, and weld ends. Values per applicable standard; customizable to requirement.
What is the lead time and MOQ?
Ready stock for standard items · made-to-order for specials · 6–8 week delivery, with small MOQ and private-label options. Ready stock is held at origin; delivery to the US is 6–8 weeks.
Where are they made, and are they TAA-eligible?
Indian origin; US / European melt available on request, with full material traceability. Standard product is India origin; US/European-melt options are offered where domestic-melt or TAA-eligibility is required. See our US-origin compliance page for how this is handled.
Do the parts come with traceability and certs?
Every part is heat/lot-number marked with EN 10204 3.1 MTC as standard (3.2 on request); QA is ISO 9001 / 14001 / 45001 & PED certified. Datasheets and CAD are available to customers on request.
Can you overtighten a twin-ferrule fitting?
Follow the manufacturer's pull-up procedure (commonly 1¼ turns from finger-tight for larger sizes; check the size-specific instruction and use a gap-inspection gauge). Consistent, gauged pull-up, not overtightening, makes a reliable joint. This is general instrumentation guidance, not brand-specific.
Other brand tube-fitting cross-references
Not a DK-LOK user? Crestflo publishes interchange guides across the instrumentation category:
- Swagelok cross-reference
- Parker A-Lok cross-reference
- Hy-Lok cross-reference
- Fitok cross-reference
- Hoke cross-reference · Gyrolok cross-reference
- All brand interchange guides · Master interchange chart
Related: DK-LOK alternative · DK-LOK vs Crestflo.
DK-LOK® is a registered trademark of DK-Lok Corporation. Crestflo is not affiliated with, authorized by, or endorsed by DK-Lok Corporation. All references are nominative and used only to identify equivalent parts. Crestflo supplies independently manufactured dimensional equivalents. Origin: Indian origin; US / European melt available on request, with full material traceability.