Tubing Information

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.

Maximum Allowable Working Pressure

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.

Factional(Inch) Tubing – Working Pressure in 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 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
Metric Tubing – Working Pressure in psig
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.

Factional(Inch) Tubing – Working Pressure is psig

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
Metric Tubing – Working Pressure is psig
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.

Factional(Inch) Tubing – Working Pressure in psig
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.

Determination Factors of MAWP at High Temperature Application
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

Pipe End Thread Information

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 .

Pressure Rating for Pipe End Thread

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

Kinds of Pipe End Thread

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.


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