TES-LOK bite-type (cutting ring) tube fittings to JIS B2351 — single-ferrule compression fittings built to the Japanese Industrial Standard, for connecting tube on Japanese-built hydraulic pumps, valves, and machinery. The hardened ring bites into the tube OD for a strong, vibration-proof grip and metal-to-metal seal. SS 316, Carbon Steel, Brass. Tube 6 mm to 50 mm OD. Pressures up to 25 MPa (248 bar / 3600 PSI). ISO 9001:2015 certified. Made in India.
TES-LOK JIS B2351 Bite-Type Fitting
DIN 2353 Bite-Type (Related)
Double-Ferrule Compression (Related)
JIS B2351 is the standard widely used on hydraulic systems built by Japanese OEMs — pumps, motors, valves, and machinery from makers such as Kawasaki, Daikin, Yuken, Nachi, KYB, and Komatsu. Although the cutting-ring principle is the same as the European DIN 2353 standard, the dimensions and thread forms differ, so the correct standard must be matched to the equipment. TES-LOK manufactures both JIS B2351 and DIN 2353 ranges.
| Criterion | JIS B2351 (Japanese) | DIN 2353 / ISO 8434-1 (European) |
|---|---|---|
| Origin / region | Japanese Industrial Standard | German / international standard |
| Mechanism | Single cutting ring bites tube OD | Single cutting ring bites tube OD |
| Dimensions | JIS-specific body, ring & thread dimensions | DIN/ISO body, ring & thread dimensions |
| Common threads | Often PT (BSPT-type) / PF (BSPP-type) Japanese threads | Metric parallel, BSPP, BSPT, NPT |
| Typical equipment | Japanese-built pumps, valves, machinery | European-built hydraulics |
| Interchangeable? | No — not interchangeable with DIN 2353 | No — match the standard to the equipment |
| Shape | Configuration | Use |
|---|---|---|
| Straight Union | Tube to tube, in-line | Joining two tubes of the same OD |
| Male Connector | Tube to male thread (PT / PF / NPT) | Tube to threaded port |
| Female Connector | Tube to female thread | Tube to male-threaded port |
| Elbow / 90° & 45° | Tube to tube or tube to thread at an angle | Direction change in tube routing |
| Tee / Cross | Three / four-way branch | Branching tube lines |
| Bulkhead Union | Tube to tube through a panel | Panel / wall pass-through connection |
| Reducer Union | Two different tube ODs | Changing tube size in a run |
| Parameter | Details |
|---|---|
| Brand | TES-LOK (Tesco Steel & Engineering) |
| Standard | JIS B2351 (Japanese Industrial Standard, cutting ring / bite type) |
| Tube OD Range | 6 mm to 50 mm OD | 1/16" to 2" OD (inch on request) |
| Working Pressure | Up to 25 MPa (248 bar / 3600 PSI) — size dependent |
| Working Temperature | −2°C to 250°C (−4°F to 482°F) — material and seal dependent |
| Thread Options | PT (taper, BSPT-type), PF (parallel, BSPP-type), NPT, metric, UNF |
| Body Material | SS 316 / 316L, SS 304, Carbon Steel (zinc/zinc-nickel plated), Brass, special alloys |
| Cutting Ring Material | Hardened steel (case-hardened) or SS 316 — matched to body |
| Seal Options | Metal-to-metal (standard) | soft-seal (FKM / NBR) ring for higher leak-tightness on request |
| Certifications | ISO 9001:2015 | EN 10204 3.1 MTC on request |
Body, cutting ring, and thread dimensions are manufactured to JIS B2351, so the fittings connect correctly to Japanese-built hydraulic pumps, valves, and machinery without dimensional mismatch — the right fitting for JIS-standard equipment.
The cutting ring is precision-hardened so its edge reliably bites into the tube OD without deforming — giving a consistent, repeatable bite and a strong anti-blow-out grip on every assembly.
The raised collar of cut tube material ahead of the ring gives a positive visual check that the bite has formed correctly — easy inspection and quality assurance at every joint.
Once the ring has bitten the tube, the joint can be disconnected and remade many times — the nut simply re-tightens onto the formed bite, making maintenance and re-routing straightforward.
Rated for working pressures up to 25 MPa (248 bar / 3600 PSI), suiting the medium- to high-pressure hydraulic circuits found on Japanese mobile and industrial equipment.
SS 316, SS 304, Carbon Steel, and Brass bodies with PT, PF, NPT, metric, and UNF threads — plus optional soft-seal rings for higher leak-tightness. EN 10204 3.1 MTC available on request.
| Industry | Typical Use Point | Why JIS B2351 Preferred |
|---|---|---|
| Japanese Hydraulic Equipment | Tube connections on Japanese-built pumps, motors, valves (Kawasaki, Daikin, Yuken, Nachi, KYB) | JIS-dimensioned fitting matches the equipment's JIS tube and ports |
| Construction & Earthmoving | Japanese excavator, loader, and crane hydraulic tube | OEM-standard JIS fittings for Japanese mobile equipment |
| Machine Tools | Hydraulic and lubrication tube on Japanese CNC and presses | Correct JIS fit on Japanese-built machinery |
| Industrial Hydraulics | Medium/high-pressure hydraulic tube on JIS-spec power units | 25 MPa rating for Japanese hydraulic circuits |
| Marine & Shipbuilding | Hydraulic tube on Japanese-built marine machinery | SS 316 corrosion resistance; JIS-standard connections |
| Material Handling | Forklift and conveyor hydraulic tube (Japanese makes) | Vibration-proof bite; OEM-matching JIS dimensions |
| Agriculture | Japanese tractor and harvester hydraulic tube | Field-serviceable, reusable JIS connections |
| Power & Process | Japanese-supplied hydraulic packages and skids | JIS fittings keep the package consistent with its origin standard |
Q1. What is a JIS B2351 bite-type tube fitting?
It is a single-ferrule cutting-ring tube fitting made to JIS B2351, the Japanese Industrial Standard for bite-type fittings. A hardened ring is driven by the body cone so its edge bites into the tube OD, locking the tube and forming a metal-to-metal seal. It is the correct fitting for tube connections on Japanese-built hydraulic equipment that uses JIS-dimensioned tube and ports.
Q2. What is the difference between JIS B2351 and DIN 2353?
Both are cutting-ring (bite-type) fittings working on the same principle, but they are dimensioned to different standards. JIS B2351 is the Japanese standard (used on Japanese-built equipment, often with PT/PF threads); DIN 2353 / ISO 8434-1 is the European/international standard (metric, BSPP, BSPT, NPT threads). Their bodies, rings, and threads are not interchangeable — the standard must be matched to the equipment.
Q3. Can I use a JIS B2351 fitting on European (DIN) equipment?
No. JIS and DIN components are not interchangeable — the body, ring, and thread dimensions differ. Use JIS B2351 fittings on Japanese-standard (JIS) equipment and DIN 2353 / ISO 8434-1 fittings on European-standard equipment. Mixing the two will prevent a correct bite and seal. If you are unsure which standard the equipment uses, check the port threads and the OEM specification.
Q4. What pressure and temperature can JIS B2351 fittings handle?
TES-LOK JIS B2351 fittings are rated for working pressures up to 25 MPa (248 bar / 3600 PSI), size dependent, and a working temperature range of about −2°C to 250°C (−4°F to 482°F) depending on body material and any soft seal used. This suits the medium- to high-pressure hydraulic circuits common on Japanese equipment.
Q5. What threads are used on JIS B2351 fittings?
JIS hydraulic fittings commonly use PT threads (tapered, equivalent to BSPT/Rc) and PF threads (parallel, equivalent to BSPP/G), as well as NPT, metric, and UNF where specified. TES-LOK can supply JIS B2351 fittings with the thread form required to match the Japanese equipment port.
Q6. What tube should I use with JIS B2351 bite-type fittings?
Use precision seamless hydraulic tube of the correct OD and wall thickness — the tube must be hard enough and thick-walled enough for the ring to bite without collapsing it, within OD tolerance, and cut square and deburred. Soft, thin-wall, or out-of-tolerance tube will not form a reliable bite. Confirm the tube OD matches the JIS fitting size.
Q7. Are JIS B2351 fittings reusable?
Yes. Once the cutting ring has bitten the tube, the joint can be disconnected and remade many times — the nut re-tightens onto the already-formed bite. The ring stays on the tube; on reassembly just inspect that the bite and seal faces are undamaged. This makes JIS B2351 fittings convenient for maintenance and re-routing.
Q8. Do you also manufacture DIN 2353 bite-type fittings?
Yes. TES-LOK manufactures both JIS B2351 and DIN 2353 / ISO 8434-1 cutting-ring tube fitting ranges, plus double-ferrule compression fittings. This lets us supply the correct fitting standard for equipment of any origin — Japanese, European, or US. See the DIN 2353 page linked in the sidebar for the European standard.