Identification Guide
Identifying a hydraulic thread comes down to three things. Get them right and you order the correct adapter the first time — no leaks, no returns.
Bosch Hydraulic Connections — known across the industry as The Metric Experts. Metric, DIN, BSPP and the full cross-standard range, in stock at three Alberta branches.
Straight threads — JIC, ORB, ORFS, BSPP, metric DIN — do not seal on the threads. They seal on a flare cone, an O-ring, a face seal, or a washer. Only tapered threads (NPT, BSPT) seal on the threads themselves.
The nine standards we stock. Each drawing is a male and female cross-section — the amber face shows where it seals, which is what tells one standard from another in your hand.
Match a measured thread to its standard. Figures follow the published SAE, ISO, ANSI and DIN standards.
| Dash | Thread (UNF) |
|---|---|
| -04 | 7/16"-20 |
| -06 | 9/16"-18 |
| -08 | 3/4"-16 |
| -10 | 7/8"-14 |
| -12 | 1-1/16"-12 |
| -16 | 1-5/16"-12 |
| -20 | 1-5/8"-12 |
| -24 | 1-7/8"-12 |
| Dash | Thread (UN/UNF) |
|---|---|
| -04 | 9/16"-18 |
| -06 | 11/16"-16 |
| -08 | 13/16"-16 |
| -10 | 1"-14 |
| -12 | 1-3/16"-12 |
| -16 | 1-7/16"-12 |
| -20 | 1-11/16"-12 |
| Size | Threads per inch | Size | Threads per inch |
|---|---|---|---|
| 1/8" | 28 | 1" | 11 |
| 1/4" | 19 | 1-1/4" | 11 |
| 3/8" | 19 | 1-1/2" | 11 |
| 1/2" | 14 | 2" | 11 |
| 3/4" | 14 |
| Series | Tube OD | Thread |
|---|---|---|
| 6L | 6 mm | M12×1.5 |
| 8L | 8 mm | M14×1.5 |
| 10L | 10 mm | M16×1.5 |
| 12L | 12 mm | M18×1.5 |
| 15L | 15 mm | M22×1.5 |
| 18L | 18 mm | M26×1.5 |
| 22L | 22 mm | M30×2 |
| 28L | 28 mm | M36×2 |
| 35L | 35 mm | M45×2 |
| 42L | 42 mm | M52×2 |
| Series | Tube OD | Thread |
|---|---|---|
| 6S | 6 mm | M14×1.5 |
| 8S | 8 mm | M16×1.5 |
| 10S | 10 mm | M18×1.5 |
| 12S | 12 mm | M20×1.5 |
| 14S | 14 mm | M22×1.5 |
| 16S | 16 mm | M24×1.5 |
| 20S | 20 mm | M30×2 |
| 25S | 25 mm | M36×2 |
| 30S | 30 mm | M42×2 |
| 38S | 38 mm | M52×2 |
These all start by hand. You won't know they're wrong until you torque them and damage a seat or shave a thread.
Nearly the same thread, but a 4° difference in the cone angle. They thread together and leak. Check the seat angle with a gauge.
Both are 9/16"-18 — an identical thread. One seals on a 37° cone, the other on a flat O-ring face. They will not seal against each other.
Both 9/16"-18 straight thread, but ORB seals on an O-ring at the base and JIC on a flare cone. Crossed, there's nothing for the seal to work against.
Same nominal pitch (e.g. 1/2"-14), but NPT is 60° and BSPT is 55°. They engage about two turns, then bind and shave the softer thread.
NPT is tapered, BSPP is parallel. Never a match — use the correct adapter.
The same thread can belong to two series: M14×1.5 is both 8L and 6S; M22×1.5 is both 15L and 14S. Measure the tube OD to confirm.
A caliper, a thread pitch gauge, and a seat-angle gauge will pin down almost any fitting.
Calipers on the male outside diameter, or the female inside diameter at the thread crest.
A thread pitch gauge gives TPI for inch threads or mm for metric — this separates the families fast (a 55° BSPP from a 60° NPT).
24° (metric DIN), 30° (JIS), 37° (JIC), 45° (SAE flare), flat O-ring face (ORFS), or O-ring at the base (ORB).
When the thread measures the same but you're unsure of the series — the metric L-vs-S trap above — the tube OD or the original equipment is the tiebreaker.
Measure the thread OD, check the pitch with a gauge, and identify the seat angle. Those three together pin down the standard.
Sometimes the threads start, but metric and BSPP are different standards and won't seal reliably. Use the correct adapter.
Both use straight threads, but JIC seals on a 37° flare cone and ORFS on a flat O-ring face. They are not interchangeable.
Yes — metric DIN, BSPP, and the full range of cross-standard adapters are our specialty, in stock at all three Alberta branches. Browse adapters →
Send us a photo or bring the fitting to any branch. Our Right Fit™ Specialists will identify it and pull the correct adapter — usually while you wait.
In stock at Edmonton, Calgary & Acheson · We ship worldwide
All dimensions follow the published SAE J514, J1453 and J1926, ISO 228, ANSI B1.20.1, and DIN 2353 / ISO 8434-1 standards. Provided as an identification aid — always verify the fitting against the original equipment before assembly. © Bosch Hydraulic Connections Ltd.