Stainless Steel Tube Fittings

Single/Twin Ferrule Compression Tube Fittings (Os-lok™ ) - General Information
Os-lok™ Tube fittings have been carefully designed and manufactured with continuous research and development backing to very stringent tolerances under rigid Quality Control procedures approved to ISO 9001-2008 quality management systems to provide zero leak, Torque free seal in instrumentation and process tubing.

Os-lok™ Tube fittings ensures maximum safety and reliability due to Tests carried out such as High pressure, impulse, vibration, vacuum, temperature, pull out and burst pressure.

 

MATERIAL
Os-lok™ Tube fittings are available as standard stainless steel 316 and 304, Brass,  Monel etc.

PRESSURE RATING
Os-lok™ Tube fitting are rated for working pressure higher than the tubing recommended in tubing data table as shown below. However, tubing should not be used above its maximum allowed working pressure. TUBING SELECTIONS
Stainless steel 304 and 316 fully annealed seamless tubing according to standard ASTM a213 or ASTM a269 or equivalent, are suitable for use with Os-lok™  tube fittings.

The tubing should be compatible with the process fluid, pressure and temperature.

For good performance of  Os-lok™  tube fittings, the tubing should be reasonably round, free from nicks, scratches, the surface finish should be good and tube ends are squarely cut and must be free from burrs.
The hardness of tubing as desired is 80Rb; the maximum allowed by ASTM is 90Rb.

TUBING DATA TABLES FOR FRACTIONAL SIZE : ALLOWABLE WORKING PRESSURE (PSI)
Tubing O.D.	WALL THICKNESS IN INCH
	0.028	0.035	0.049	0.065	0.083	0.095	0.109	0.120
1/8	8600	10900
3/16	5500	7000	10300
1/4	4000	5100	7500	10300
5/16		4100	5900	8100
3/8		3300	4800	6600
1/2		2600	3700	5100	6700
5/8			3000	4000	5200	6100
3/4			2400	3300	4300	5000	5800
7/8			2100	2800	3600	4200	4900
1				2400	3200	3700	4200	4700

 

TUBING DATA TABLES FOR METRIC SIZE : ALLOWABLE WORKING PRESSURE IN BAR
Tubing O.D.	WALL THICKNESS IN MILLIMETER
	0.5	0.6	0.7	0.8	1.0	1.2	1.5	1.6	1.8	2.0	2.2	2.5	3.0
3	497	607	718	828	1032
6			331	386	497	607	774	912
8			208	280	359	440	558	607
10				221	280	342	440	473
12				182	231	280	359	386	440	497
14					195	237	302	324	369	416	463	535	654
16					169	205	361	280	319	358	398	460	564
18					150	181	230	246	280	314	349	403	496
22					121	147	185	199	225	252	280	322	394
25					108	128	162	173	196	220	244	280	342

Note: 
Working pressure (psig) for seamless tubing. Multiply pressure rating by 0.80 for single welded tubing. Multiply pressure rating by 0.85 for double welded tubing.

FACTORS USED TO DETERMINE ALLOWABLE PRESSURE AT HIGHER TEMPERATURES.
°F	°C	a.I.S.I. 316
200	93	1
400	204	0.96
600	316	0.85
800	427	0.79
1000	538	0.76
1200	649	0.37

For Example : 
The allowable pressure for type SS316, Size 1/4"OD x 0.035 wall at 600°F(316°C) would be equivalent to 5100 psi x 0.85 = 4335 psi.

GAS SERVICE 

Extra care must be taken while selecting tubing for gas application, In order to achieve a gas-tight seal, ferrules in instruments fittings must seal any minor surface imperfections.

The thick walled tubing helps the ferrules to overcome minor surface imperfections

OSHWIN recommends the following minimum wall thickness of tubing for gas application

GAS APPLICATION TUBING

GAS APPLICATION TUBING

Tube OD  (Inches) Nominal Minimum Wall Thickness (Inches) 1/8" 0.028" 3/16" 0.028" 1/4" 0.028" 5/16" 0.035" 3/8" 0.035" 1/2" 0.049" 5/8" 0.065" 3/4" 0.065" 7/8" 0.083" 1" 0.083"

Tube OD  (Metric) Nominal Minimum Wall Thickness (Metric) 3 mm 0.8 mm 6 mm 0.8 mm 8 mm 1.0 mm 10 mm 1.0 mm 12 mm 1.0 mm 14 mm 1.2 mm 16 mm 1.5 mm 18 mm 1.5 mm 20 mm 1.8 mm 22 mm 2.0 mm 25 mm 2.2 mm

PIPE END NPT and ISO PRESSURE RATINGS

Fitting that has both tube and pipe thread ends can have different pressure ratings. The pipe end pressure ratings chart given below for SS316 shows the pressure ratings for male and female pipe thread ends.

Working pressure is calculated on ANSI code for pressure piping B31.3 basis.