DK-Lok Tubing
Rev. 01-01
Aug. 2023

DK-Lok Tubing

Stainless Steel Instrumentation Fractional / Metric Tubing

DK-Lok Tubing

Tubing benefits

Tubing has many benefits against piping• Pipe threading or welding is difficult to disassemble andre-assemble.
• Piping requires skilled worker for welding & threading.
• Piping is bulky.
• Tubing is assembled by simple wrench make-up on DK-Lok Tube
Fittings reducing assembly time and the overall cost ofinstallation.
• Tubing is bendable, allowing lower pressure drop with fewer
connections. This in turn reduces costs with less fabricatingmanpower.

DK-Lok Tubing Features

For the best performance with DK-Lok fittings, DK offers ASTM A269
and A213 bright annealed DK-Lok tubing 1/8 in. to 1 in. OD with thefollowing features:• Seamless and suitable for bending and flaring.
• Free of scratches, drawing, dirt, and dust and other contamination.
• Chemically cleaned and passivated surface.
• Cold drawn and bright annealed.
• Hardness 80 HRB or less.

DK-Lok Tubing marking and packaging• Marking on tubing includes OD, wall thickness(WT), material grade,specification, heat code, and country of origin.
• Tubing ends to be capped.
• A certain quantity to be packaged in a protective cover andthen packed in a wooden crate.

DK-Lok Tubing standard length

6 meter tubing cut length variations as per the requirement of ASTM
A450 standard.

DK-Lok Tubing ovality in OD and variations in WT

ASTM A269 specifies permissible variation in tubing OD and WT, reads:
Tube O.D.
In
Up to 1/2

1/2 to 1 1/2, excl

Permissible
variation in OD,
In. (mm)

Permissible variationin WT, %+ / - 0.005 (0.13)+ / - 10%+ / - 0.005 (0.13)+ / - 15%

The following parameters should be considered when ordering
instrumentation bright annealed seamless and welded tubing.
1. Tubing Selection
2. Tubing Handling
3. Tubing Installation
4. System Pressure
5. Welded Tubing Working Pressure

Tubing SelectionHardness

1. Tubing must be softer than fitting material. The metal tubing
must be fully annealed and suitable for bending and flaring.
2. Tubing hardness must be selected according to the informationin the table 4 and 5.

Surface

3. Tubing must have a surface free from scratches, draw mark, dirt,durst and flat spots.

Ovality

4. Tubing in oval or out-of-roundness may not fit into the fitting.
Do not force the tubing into the fitting; it may damage the fitting
sealing system on the nut, ferrules, and body.

5. Material

Using like tubing and fitting material is essential for the thermalcompatibility and corrosion resistance. Different materials havedifferent hardness level that may adversely affect the fitting seal
on tubing. The only exception is copper tubing with brass DK-LokFittings.

6. Wall thickness

The table 4 and 5 show tubing working pressure ratings in a wide
range of wall thickness. A too thin of a wall may collapse and too
thick wall may not properly be deformed by the ferrule action.
DK-Lok Fittings are not recommended for tube wall thickness notlisted in the table 4 and 5.

7. Wall thickness for gas application

Solution annealed.

8. Weld tubing

Surface Condition

Bright annealed with thermocouple clean level on the insidesurface as per ASTM A632 S3.

1For safe, reliable and leak-free tubing system for use with DK-Lok
Fittings , tubing should be considered as one of fitting components.

Tubing ovality variation in OD as per the requirements of ASTM A269.
For tubing OD 1/8 in. and smaller, DK supplies +/- 0.003 inch
variations for the leak-free performance with stainless steel 316
DK-Lok Fittings.
Tubing WT variations as specified in the ASTM A269 standard.
See Table 4 and 5.

Heat Treatment

Rev.01-01
Aug.2023

Gases such as nitrogen, air, hydrogen and helium, can escapeeven the most minute leak path due to their small molecules.
Heavy wall tubing resists ferrule action by coining out minor
defects of the tube surface whereas a thin wall may collapse withlittle resistance to ferrule action. For gas service, use heavy wall inwhite in table 4 and 5.
The weld bead should not be noticeable visually on the outsideof the tube.

Note:

Tubing of ornamental, structural or mechanical grade should not be used for fluid
system.

All dimensions are in millimeters unless otherwise specified and only for reference subject to change.

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Tubing Handling

Careful handling and storage practices will protect tubing from unnecessary scratches, nicks and or degrading good tubing surface finish• Tubing ends should be capped so any foreign materials will not fall inside during transportation and storage.
• Do not drag across tubing rack, cement, gravel or any rough surface.
• Do use correct tube cutter for tube material. The wrong cutter may result in excessive deformation of the tube end.
• Do not cut deep with each turn of cutter.
• Tube cutters and hacksaws should be sharp enough.
• Hacksaw blades should have at least 32 teeth per inch.
• Deburring tube ends before inserting in the tube fittings helps prevent against system containments.

Tubing Installation

System pressure

DK-Lok Fitting pressure ratings are governed by the connective
tubing pressure rating. To determine allowable working pressure atelevated temperature, multiply the working pressure at ambient
temperature shown in table 4 and 5 by the factor shown in table 2.

Example:SS316 seamless tubing 1/2 in. O.D. x 0.065 in. WT
at 700 F. 4700 psig x 0.82 = 3854 psig.
Therefore 3854 psig is the maximum allowable working pressure
at 700 of for SS316 seamless 1/2 in. O.D. x 0.065 in. wall thickness tubing.

T : Tube OD
R : Radius
L : Straight tube length

Table 2. Temperature De-rating Factors°F

Temperature

100300

When tube bend is too close to a fitting, the bend section shall enter
the fitting. This may not allow the tube to be bottomed out in thefitting, and may result in leakage.
Keep the proper straight length of tube as shown in table 1 below.
• Do not bend a tube in the fitting. Use tube bender.

Table 1.

Fractional tube, in.

TMetric tube, mmL

T

1/8

23/32

6

1/4

13/16

1015/16

14

1/16
3/16
5/16
3/8
1/2
5/8
3/4

1/2
3/4

7/8

1 3/16
1 1/4
1 1/4

7/8

1 5/16

1 1/4

2

1

1 1/2
2

1 1/2

2 13/32
3 1/4

L

19

8

23

12
15
16
18
20
22
25
28
30
32
38
50

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21
25
31
32
32
32
32
34
34
40
46
50
54
63

93

1149

400

204

500

600

1
11

316

0.82

0.85

427

0.76

371

900

482

538

1200

1SS316

0.97

700
800

10.94

260

1000

3SS30438200

Stainless steel ASTM A269°C

649

0.88
0.8

0.73

0.69
0.3

0.9

0.82
0.80.780.77
0.37

Table 3. Elastomer seal working temperature
Elastomer Seals

Working Temperature

NBR-40 to 110°C(-40 to 230°F)

FFKM (Kalrez®)-30 to 275°C(-22 to 527°F)

FKM-20 to 200°C(-4 to 392°F)

When Elastomer seal is used in the system, care must be taken forallowable working temperature. See Table 3* Kalrez®: TM Dupont

Welded Tubing Working Pressure

As per ASME B31.3 Code for weld tubing working pressure, de-rating
factors below must be applied. For double butt weld tubing multiply
by 0.85 and for single butt weld tubing multiply by 0.80.
Example:SS316 single butt weld tubing 1/2 in. O.D. x 0.065 in.
4700 psig x 0.80 = 3760 psig at -20 to 100°F (-28 to 37°C).

80

All dimensions are in millimeters unless otherwise specified and only for reference subject to change.

2

Cryogenic Service• SS316 DK-Lok Fittings provide highly reliable performance from cryogenic to high temperature.
• SS316 DK-Lok Fitting and tubing temperature Rating: -425 to 1200°F (-253 to 649 °C)• Cryogenic temperature are considered temperatures below -100°F (-73 °C)

Table 4. Tubing Material Grade and Chemical Requirements
ASTM

Material GradeS31600

Chromium16.0 to 18.0

Molybdenum

2.00 to 3.00

GradeTP316

Nickel

S31603

S31600TP316L10.0 to 14.0

Manganese

Chemical %

A269

UNS

2.00 max

SiliconCarbon1.00

0.08 max

Phosphorus

0.045 max

Sulfur

A213 (a) / A249

TP316

TP316L11.0 to 14.0

10.0 to 15.0

0.75 max

0.035 max (c)(a) Nominal wall thickness, not minimum
wall thickness.
(b) For seamless TP316L tube, the silicon
maximum shall be 1.00%.
(c) For smaller diameter or thin walls,or both, where many drawing passes
are required, a carbon maximum of
0.040% is necessary in grade TP316L.
This is applicable tubing size less than
1/2 in. OD and less than 0.049 in.
(1.2 mm) in WT.

0.75 max (b)0.08 max

0.035 max (c)0.040 max

0.030 max

ASTM Standards

S31603

Stainless Steel Tubing

Fully annealed austenitic Type 304 or 316 seamless tubing ASTM A269 or A213, or equivalent. Tubing to be free from scratches, draw mark,dirt, durst and flat spots. Suitable for bending and flaring.

Table 5. Seamless Stainless Steel Fractional Tubing (Recommended hardness: 80 HRB (180 HV) or less.)
Tube OD
In.

1/16

1/8

0.012

0.014

6800

0.016

8100

9400

0.02

12000

3/16

0.028

0.035

8500

10900

4000

5100

5400

1/4

5/16
3/8

Tube Wall Thickness, in.

0.049

7000

10200

4000

5800

2400

3500

3300

1/2
5/8

7500

10200

4800

6500

2900

3/4

2400

7/8

2000

10.065

1 1/4

0.083

0.095

0.109

6200

4000

5200

3300

2800

6000

4200

4900

5800

6400

3100

3600

4200

4700

3600

2400

4200

2400

4800

2800

3300

2300

2700

368

10

1.5

330

420

520

670

240

300

380

710

310

12200

15

170

14
16
18

20

2225

28

30

32

38
3

1.2

180

380
240

1.8

Tube Wall Thickness, mm
2

380

430

200

260

320

360

170

210

190
150

130

2.5

2.8

3490
310

220

2.2

280

240
190

170

340
300
260

230

210

180

430

330

370

260

230

200

180

170

160

4

4.5

Working Pressure in Bar390
290

3.5

400
320

290

260

230

200

370

330

300

260

230

190

210

140

170

170

200

380

340

300

260

240

230

190

320

280

260

240

200

330

310

290

240

All dimensions are in millimeters unless otherwise specified and only for reference subject to change.

330

280

5400

6100

3600

4100

3000

2000

Table 6. Seamless Stainless Steel MetricTubing (Recommended hardness: 80 HRB (180 HV) or less.)
10.156

0.188

8600

4700

20.8

0.134

Working Pressure in PSIG

8000

1 1/2

Tube ODmm

0.12

2200

5300

6200

3400

4000

2500

4900
2900

4900

3600

• ASTM A269 tubing allowable working
pressure is calculated at -20 to 100°F(-28 to 37°C) using allowable stressvalue of 20,000 psi according toASME B31.3 Code.
• Pressure calculations are based on
maximum O.D. and minimum wall
thickness and no allowance is made forcorrosion and erosion. i.e, ASTM A269
1/2 in. OD x 0.035 in.: OD tolerance ±0.005 in., WT tolerance ± 15%.
Calculations are based on 0.505 in.ODx 0.0298 in. WT.
• Safety Factor is 3.75 to 1, considering
ultimate tensile strength of 75,000 psi.
• For working pressure according toASME B31.1, multiply the ASME 31.3
rating by 0.94.

310

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Ordering information

DK-Lok A269/A213 seamless bright annealed stainless steel grade TP316/316L tubing.
Tube ODin.
1/8

1/4

3/8

1/2

3/4

Nominal WallThickness (in.)

Tube OD
mm

Nominal Wall
Thickness (mm)TL2-035-x-S

6

1.20

0.028

TL2-028-x-S

0.028

TL4-028-x-S

0.035
0.035

TL4-035-x-S

0.049

TL4-049-x-S

0.065

TL4-065-x-S

0.035

TL6-035-x-S

0.049

TL6-049-x-S

0.065

TL6-065-x-S

0.083

TL6-083-x-S

0.035

TL8-035-x-S

0.049

TL8-049-x-S

0.065
0.083

TL8-065-x-S
TL12-065-x-S

0.095

TL12-095-x-S

0.083
0.109
0.083

0.095
0.109
0.120
0.134
0.156

81012TL8-083-x-S

0.065

0.120

1OrderingNumberTL12-083-x-S
TL12-109-x-S

TL16-095-x-S
TL16-109-x-S
TL16-120-x-S
TL16-134-x-S

TL6M-1.0-x-S

1.50

TL6M-1.5-x-S

1.00
1.20
1.50

TL8M-1.0-x-S
TL8M-1.2-x-S
TL8M-1.5-x-S

TL10M-1.0-x-S

1.50

TL10M-1.5-x-S

1.20
1.20
1.50
1.80
2.00
2.00
2.20
2.50
1.80

25

TL6M-1.2-x-S

1.00

2.80

TL12-120-x-S
TL16-083-x-S

1.00

1.80
20

Ordering
Number

2.00
2.50
2.80
3.00

TL10M-1.2-x-S
TL12M-1.2-x-S
TL12M-1.5-x-S
TL12M-1.8-x-S
TL12M-2.0-x-S
TL20M-1.8-x-S
TL20M-2.0-x-S
TL20M-2.2-x-S
TL20M-2.5-x-S
TL20M-2.8-x-S
TL25M-1.8-x-S
TL25M-2.0-x-S
TL25M-2.5-x-S
TL25M-2.8-x-S
TL25M-3.0-x-S

TL16-156-x-S

To order tubing in 6 meter length, insert “6M” into the ordering number.
To order tubing in 20 feet length, insert “20” into the ordering number.

To order weld tubing remove “L" after T in the ordering number.
To order annealed & pickled A269 seamless SS316 tubing, insert “AP” in the ordering number.

Example: TL8-035-6M-S
Example: TL8-035-20-S

Example: T8-035-6M-S
Example: TL8-083-6M-AP-S

Reference Documents• ASTM A213		Seamless Ferritic and Austenitic Alloy-Steel Boiler, Super heater, and Heat-Exchanger Tubes• ASTM A249		Welded Austenitic Steel Boiler, Super heater, Heat Exchanger, and Condenser Tubes• ASTM A269		Seamless and Welded Austenitic Stainless Tubing for General Service• ASTM A450		General Requirements for Carbon, Ferritic Alloy, and Austenitic Alloy Steel Tubes• ASTM A632 		Seamless and welded Austenitic Stainless Steel Tubing (Small-Diameter) for General Service• DIN 2391/EN10305		Precision Seamless Tubes• DIN 17458/2462		Seamless Circular Tubes of Austenitic Stainless Steels with Special Quality Requirements

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All dimensions are in millimeters unless otherwise specified and only for reference subject to change.

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