Thread Identification Thread Form
Step 1: Determine if Tapered or Parallel
UN/UNF (SAE)
Parallel
12, 14, 16, 18, 20, 24
NPT/NPTF (American)
Tapered
11 ½, 14, 18, 27
Double-check w/ Caliper (mm&in.)
BSPP (British Pipe)
Parallel
11, 14, 19, 28
Nominal Sizeuse Thread Profile
BSPT (British Pipe)
Tapered
Step 2: Determine Pitch
11, 14, 19, 28
Metric
Parallel
1.0, 1.5, 2.0
Metric
Tapered
1.0, 1.5, 2.0
Dash Size
Tube OD
-02 -03 -04 -05 -06 -07 -08 -10 -12 -14 -16 -20 -24 -32
1/8 3/16 1/4 5/16 3/8 7/16 1/2 5/8 3/4 7/8 1 1.1/4 1.1/2 2
Step 3: Determine Size (O.D.)
Step 4: Define Thread with Standard Threads Chart
Measure with Caliper (mm&in.)
Size-Pitch, Type
(25.4mm=1 inch)
Double-check w/ Thread Profile
Nominal Sizeuse Thread Profile
EX: ¾ - 16 UNF Size-Pitch, Type EX: ¼ - 18 NPT(P) G, Size-Pitch
Double-check w/ Caliper (mm&in.)
EX: G1/8 - 28 R, Size-Pitch
Double-check w/ Caliper (mm&in.)
EX: R1/2 - 14 M, Size x Pitch EX: M14 x 1.5 M, Size x Pitch, tapered EX: M10 x 1 tapered
Nominal Sizeuse Thread Profile
Measure with Caliper (use mm)
Measure with Caliper (use mm)
Pipe & Tube Fittings - STANDARD THREADS CHART BSPT-BSPP Pipe SAE O-Ring (ORB)/UNF Thread/UNF NPT Pipe Thread Thread (ORFS) or JIC 37 Flare Nom - TPI OD (in) Nom - TPI OD (in) OD - TPI OD - TPI 1/8-27 0.405 1/8-28 0.400 5/16-24 3/8-24 1/4-18 0.540 1/4-19 0.538 7/16-20 9/16-18 1/2-20 3/8-18 0.675 3/8-19 11/16-16 0.676 9/16-18 1/2-14 0.840 1/2-14 0.847 3/4-16 13/16-16 7/8-14 1-14 3/4-14 1.050 3/4-14 1.063 1.1/16-12 1.3/16-12 1.3/16-12 1-11.1/2 1.315 1-11 1.336 1.5/16-12 1.7/16-12 1.1/4-11.1/2 1.660 1.1/4-11 1.677 1.5/8-12 1.11/16-12 1.1/2-11.1/2 1.900 1.1/2-11 1.909 1.7/8-12 2-12 2-11.1/2 2.375 2-11 2.381 2.1/2-12 For NPT, Dash - 02, Actual size 1/8". 1/8-27 OD of the means 1/8" thread in nominal size and inches. 27 TPI (threads 25.4mm= per inch). The 1inch. actual OD of 1/8" NPT thread is 0.405".
(Below)
For SAE O-Ring: Dash - 02, size Flat Face Thread Actual OD of the 1/8". 5/16-24 means thread OD (ORFS) = CAST 4000 thread in is 5/16 and has 24TPI. Also series. Also UNF. inches. called O-Ring Boss and is a type of UNF Thread. SAE O-Ring=(CAST 25.4mm= ex. 1009, 1063, 2005, etc.) JIC 1inch. Flare = CAST 2000 series.
45 SAE Flare OD - TPI 5/16-24 3/8-24 7/16-20 1/2-20 5/8-18 11/16-16 3/4-16 7/8-14 1.1/16-14 -
Inverted Brass Flare Compression OD - TPI OD - TPI 5/16-24 5/16-28 3/8-24 3/8-24 7/16-24 7/16-24 1/2-24 1/2-24 9/16-24 9/16-24 5/8-24 5/8-24 11/16-20 11/16-20 13/16-18 13/16-18 1-18 1-18 -