The proper selection of tubing is essential to assure maximum fitting reliability and performance. When choosing tubing material,
size and wall thickness, consider system’s pressure, flow rate, temperature, environment and compatibility with great care.
Stainless Steel Tubing
Fully annealed and seamless stainless steel tubing to comply with ASTM A269 or equivalent. Hardness should not exceed Rb 80.
Tubing should be free from scratched and suitable for bending and flaring.
| Tube O.D (Inch) |
Tube Wall Thickness (Inch) | ||||||||||
| 0.028 | 0.035 | 0.049 | 0.065 | 0.083 | 0.095 | 0.109 | 0.120 | 0.134 | 0.156 | 0.188 | |
| 1/8 | 8550 | 10950 | |||||||||
| 3/16 | 5500 | 7100 | 10300 | ||||||||
| 1/4 | 4100 | 5200 | 7600 | 10300 | |||||||
| 5/16 | 4100 | 5900 | 8100 | ||||||||
| 3/8 | 3350 | 4850 | 6550 | ||||||||
| 1/2 | 2650 | 3750 | 5150 | 6750 | |||||||
| 5/8 | 2950 | 4050 | 5250 | 6050 | |||||||
| 3/4 | 2450 | 3350 | 4250 | 4950 | 5850 | ||||||
| 4/8 | 2050 | 2850 | 3650 | 4250 | 4850 | ||||||
| 1 | 2400 | 3100 | 3600 | 4200 | 4700 | ||||||
| 1-1/4 | 2400 | 2800 | 3300 | 3600 | 4100 | 4900 | |||||
| 1-1/2 | 2300 | 2700 | 3000 | 3400 | 4000 | 4900 | |||||
| 2 | 2000 | 2200 | 2500 | 2900 | 3600 | ||||||
| Tube O.D (mm) |
Tube Wall Thickness (Inch) | ||||||||||
| 0.8 | 1.0 | 1.2 | 1.5 | 2.0 | 2.2 | 2.5 | 3.0 | 3.5 | 4.0 | 4.5 | |
| 3 | 9700 | ||||||||||
| 4 | 7900 | 11500 | |||||||||
| 6 | 4500 | 6100 | 7850 | 10300 | |||||||
| 8 | 4500 | 5650 | 7500 | ||||||||
| 10 | 3500 | 4350 | 5800 | 8400 | |||||||
| 12 | 2900 | 3600 | 4800 | 6800 | |||||||
| 14 | 2300 | 2900 | 4000 | 5500 | 6250 | ||||||
| 15 | 200 | 2750 | 3650 | 5200 | 5800 | ||||||
| 16 | 2450 | 3350 | 4800 | 5350 | 5800 | ||||||
| 18 | 2150 | 2950 | 4200 | 4650 | 5350 | 5800 | |||||
| 20 | 2030 | 2600 | 3750 | 4200 | 4800 | ||||||
| 22 | 1750 | 2300 | 3350 | 3750 | 4350 | ||||||
| 25 | 2900 | 3350 | 3750 | 4650 | |||||||
| 38 | 2030 | 2300 | 2900 | 3500 | 3900 | 4500 | |||||
For gas service application, use only tubing with wall thickness on outside of gray areas. Allowable stress of 20000 psig between
-29°C(-20°F) and 37°C(100°F) based on ultimate tensile strength to be 74000 psig.
Copper
Tubing Fully annealed and seamless stainless steel tubing to comply with ASTM B75 or equivalent. Hardness should not exceed Rb 60.
For gas service application, use only tubing with wall thickness on outside of gray areas. Allowable stress of 6000 psig between
-29℃(-20℉) and 37℃ (100℉) based on ultimate tensile strength to be 30000 psig.
| Tube O.D (Inch) |
Tube Wall Thickness (Inch) | |||||||
| 0.028 | 0.035 | 0.049 | 0.065 | 0.083 | 0.095 | 0.109 | 0.120 | |
| 1/4 | 1300 | 1600 | 2500 | 3500 | ||||
| 3/8 | 1000 | 1600 | 2200 | |||||
| 1/2 | 800 | 1100 | 1600 | 2200 | ||||
| 5/8 | 900 | 1200 | 1600 | 1900 | ||||
| 3/4 | 700 | 1000 | 1300 | 1500 | 1800 | |||
| 1 | 500 | 700 | 900 | 1100 | 1300 | 1500 | ||
| Tube O.D. | Tube Wall Thickness (inch) | ||||
| 1.0 | 1.5 | 2.0 | 2.5 | 30 | |
| 6 | 2350 | 3670 | |||
| 8 | 1710 | 2680 | |||
| 10 | 1350 | 2090 | |||
| 12 | 1100 | 1710 | 2350 | ||
| 20 | 990 | 1350 | 1710 | ||
| 25 | 780 | 1060 | 1350 | 1640 | |
Monel Tubing
Fully annealed and seamless stainless steel tubing to comply with ASTM B165 or equivalent. Hardness should not exceed Rockwell Rb 75.
| Tube O.D (Inch) |
Tube Wall Thickness (Inch) | ||||||
| 0.035 | 0.049 | 0.065 | 0.083 | 0.095 | 0.109 | 0.120 | |
| 1/4 | 4800 | 7000 | 9500 | ||||
| 3/8 | 3100 | 4400 | 6100 | ||||
| 1/2 | 2300 | 3200 | 4400 | ||||
| 5/8 | 2200 | 3000 | 4000 | 4600 | |||
| 3/4 | 2200 | 2900 | 3400 | 3900 | 4300 | ||
For gas service application, use only tubing with wall thickness on outside of gray areas. Allowable stress of 6000 psig between
-29℃(-20℉) and 37℃ (100℉) based on ultimate tensile strength to be 30000 psig.
| Temperature | Materials | |||
| °C | °F | 316SS | Copper | Monel |
| 90 | 194 | 1.00 | 0.80 | 0.88 |
| 200 | 392 | 0.96 | 0.50 | 0.79 |
| 310 | 590 | 0.85 | – | 0.79 |
| 480 | 802 | 0.79 | – | 0.75 |
| 536 | 996 | 0.76 | – | – |
| 644 | 1227 | 0.37 | – | – |
To determine allowable working pressure at elevated temperature,
multiply allowable working pressure and factors which are shown in the table.
Example: 316SS Tubing, 1/2″ODx0.049″WT at 310℃ AWP: 3750 x 0.85 = 3187 psig.
* MAWP: Maximum Allowable Working Pressure
* AWP: Allowable Working Pressure
The end connections with the lower pressure rating is the determining factor of pressure rating for the fittings with both UNILOK tube ends and pipe thread ends .
Tapered Pipe Threads – NPT or ISO 7/1(BSPT)
Allowable pressure ratings for male and female threads are based on ASME B31.3 at ambient temperature.
| Pipe Size |
316SS | 316SS | UNILOK Designator |
|||||
| Male | Female | Male | Female | |||||
| inch | bar | psig | bar | psig | psig | bar | psig | |
| 1/16 | 760 | 11000 | 460 | 6700 | 5500 | 230 | 3300 | -01N/R |
| 1/8 | 690 | 10000 | 440 | 6500 | 5000 | 220 | 3200 | -02N/R |
| 1/4 | 550 | 8000 | 450 | 6600 | 4000 | 220 | 3300 | -04N/R |
| 3/8 | 540 | 7800 | 360 | 5300 | 3900 | 180 | 2600 | -06N/R |
| 1/2 | 530 | 7700 | 330 | 4900 | 3800 | 160 | 2400 | -08N/R |
| 3/4 | 500 | 7300 | 320 | 4600 | 3600 | 160 | 2300 | -12N/R |
| 1 | 370 | 5300 | 300 | 4400 | 2600 | 150 | 2200 | -16N/R |
| 1-1/4 | 410 | 6000 | 350 | 5000 | 3000 | 170 | 2500 | -20N/R |
| 1-1/2 | 340 | 5000 | 310 | 4600 | 2500 | 150 | 2300 | -24N/R |
| 2 | 270 | 3900 | 270 | 3900 | 1900 | 130 | 1900 | -32N/R |
ISO 228/1 Parallel Thread (BSPP)
The pressure ratings are at ambient temperature
| Male Pipe Size |
316SS | UNILOK Designator |
|
| bar | psig | ||
| 1/8 | 315 | 4568 | -02G |
| 1/4 | 315 | 4568 | -04G |
| 3/8 | 315 | 4568 | -06G |
| 1/2 | 160 | 2320 | -08G |
O-Seal Fittings
Rated to 206 bar (3000 psig) for 316SS fittings up to 1 inch and 25mm
NPT Pipe Thread
NPT (National Pipe Thread) is based on ANSI B1.20.1
ISO 7/1 Tapered Pipe Thread
International Organization for Standard (ISO 7/1) Tapered (PT) Equivalent to BSPT (British Standard Pipe Taper Thread), DIN 2999, JIS B0203
ISO 228/1 Parallel Pipe Thread
International Organization for Standard (ISO 228/1) Parallel(PF) Equivalent to BSPP (British Standard Pipe Parallel Thread), DIN ISO228/1, JIS B0202 Gasket or O-ring is normally used to seal into the parallel female threaded components.