Size and thread charts
BSP, NPT, JIC/UNF, ORFS and metric 24° (DIN 2353) thread and fitting dimensions, SAE flange and hydraulic hose charts, plus a thread identification tool. Values are based on ISO, SAE and ASME standards, to help you identify the part in your hand and choose the right connection.
Thread identification tool
Enter the diameter and thread pitch you measured with a caliper; the tool lists the closest candidates among BSP, NPT, UN/UNF and metric fine threads and shows how to tell commonly confused threads apart.
Open the tool7 charts
Values are nominal; for critical applications, verify against the current standard and the manufacturer's catalog.
Major diameter, minor diameter, pitch and threads per inch of BSPP (G, ISO 228-1) and BSPT (R, Rc, Rp; ISO 7-1) threads from 1/8" to 2"; the…
Threads per inch, pitch, pipe OD, DN equivalent and approximate tap drill sizes for ASME B1.20.1 NPT and ASME B1.20.3 NPTF tapered pipe threads from…
Dash sizes -2 to -32 for JIC 37° (SAE J514) and SAE O-ring boss (SAE J1926) connections: tube OD, UN/UNF thread, pitch and the typical reading ranges…
LL, L and S series of DIN 2353 / ISO 8434-1 24° cone fittings with cutting rings: tube OD, nut thread, pitch, ISO working pressure and the matching…
Bolt spacing, UNC bolts, O-ring sizes and working pressures of SAE J518 / ISO 6162 four-bolt flanges in Code 61 (SAE 3000) and Code 62 (SAE 6000)…
Dash sizes -4 to -24 for ORFS (O-ring face seal, SAE J1453 / ISO 8434-3) connections: tube OD, UN/UNF thread, typical reading range and face O-ring…
Hydraulic hose dash sizes from -3 to -32, nominal inside diameter (inches and mm) and catalog DN equivalent; how hose size is measured and how it…
Glossary of Hydraulic Terms Short definitions of hydraulic fitting, thread, flange, hose and stainless steel material terms: BSP, NPT, JIC, ORFS, DIN 2353, dash size, bonded seal, 316L and more.
Open the glossaryStandards
This section brings together the size and thread charts most often needed for hydraulic connections: BSP, NPT, JIC/UNF, ORFS and metric 24° fitting threads, SAE flange connection dimensions and hydraulic hose sizes. If you don't know the standard of the part in your hand, start with the thread identification tool: enter the diameter and pitch you measured to see the closest candidates.
Three features define a hydraulic connection: the thread profile angle, whether the thread is parallel or tapered, and where the seal is made. Outside diameter and pitch are only part of the picture. The table below compares the standards most often found in the field on these features.
| Standard | Profile angle | Thread form | Sealing | Typical use |
|---|---|---|---|---|
| BSPP (G, ISO 228-1) | 55° | Parallel | Bonded seal, O-ring or 60° cone | Pump, valve and hose end ports of European and Asian origin |
| BSPT (R / Rc, ISO 7-1) | 55° | Tapered, 1:16 | On the thread; sealing tape or liquid thread sealant | Pipework, plugs and tapered male ends |
| NPT / NPTF (ASME B1.20.1 / B1.20.3) | 60° | Tapered, 1:16 | On the thread; NPT needs a sealant, NPTF is designed for a dry seal | Equipment of North American origin, instrumentation and process lines |
| JIC 37° (SAE J514 / ISO 8434-2) | 60° (UN/UNF thread) | Parallel | Metal-to-metal contact on the 37° flare cone | US-standard machinery, hose and tube ends |
| SAE ORB (SAE J1926 / ISO 11926) | 60° (UN/UNF thread) | Parallel | O-ring compressed in the port chamfer | US-standard pump, valve and cylinder ports |
| ORFS (SAE J1453 / ISO 8434-3) | 60° (UN/UNF thread) | Parallel | O-ring in a groove on the flat face | High-pressure and high-vibration lines, construction machinery |
| Metric 24° cone (DIN 2353 / ISO 8434-1) | 60° (metric fine thread) | Parallel | Cutting ring or O-ring cone end seated in the 24° cone | Metric OD tube lines; L and S series |
| Metric port (ISO 6149) | 60° | Parallel | O-ring compressed in the port chamfer | Metric machine ports, stud ends of 24° fittings |
| SAE flange (SAE J518 / ISO 6162-1, -2) | No thread, 4 bolts | — | O-ring in the flange head | Large-bore pump outlets, valve blocks and cylinder feeds; Code 61 and Code 62 |
Dimensions in the charts are the nominal values of the relevant ISO, SAE and ASME standards; the "typical reading" columns show the value you can expect with a caliper and are not inspection criteria. Pressure columns are the values given in the standard: ISO 8434-1 values are for carbon steel bodies, and the standard leaves the pressure rating of stainless steel bodies to the manufacturer. For the usable pressure of an AISI 316/316L part, go by the value given in the quotation and product information.
Values are nominal; for critical applications, verify against the current standard and the manufacturer's catalog.
FAQ
If your question isn't answered here, message us on WhatsApp with dimensions or a photo, and our technical team will answer directly.
Ask on WhatsAppA fitting size is not given by a single number; it depends on the connection type. Metric 24° fittings use the tube OD and series (e.g. 12L), JIC and ORFS connections use the dash number (e.g. -8), BSP and NPT threads use the nominal size (e.g. G 1/2, 1/2" NPT) and SAE flanges use the nominal size and series (e.g. 1" Code 61). When requesting a quote, stating the thread standard, size and sealing type together prevents mistakes.
A G 1/2 (1/2" BSPP) thread has a major diameter of 20.955 mm and a minor diameter of 18.631 mm; it has 14 threads per inch and a pitch of 1.814 mm. "1/2 inch" comes from the pipe size convention and is not the actual thread diameter. A 1/2" NPT of the same nominal size has a pipe OD of 21.336 mm and a 60° thread profile.
Not directly. The ISO 8434-1 pressures in the metric 24° chart are for carbon steel bodies; the standard leaves the pressure rating of stainless steel bodies to the manufacturer. On SAE flanges, too, the allowable pressure of a stainless steel connection drops at elevated temperature; take the derating from the manufacturer's value. For the usable pressure of an AISI 316/316L part, go by the value given in the quotation and product information.
Measure the outside diameter of a male thread or the inside diameter of a female thread with a caliper; find the pitch with a pitch gauge and check whether the thread is parallel or tapered. Enter these values into the thread identification tool to see the closest candidates. If you're still unsure, send a photo of the part with a caliper in the shot on WhatsApp, and we'll confirm the standard together.
From chart to quote
Tell us the thread standard, size and quantity, or send a photo of the part; we'll get back to you with a stock or manufacturing option for an AISI 316/316L stainless steel fitting.
