Cat16 R2

Metal Tubes - Technical Information, Applications, and Suggestions

Metal Protection Tubes -

Some General Suggestions for Effective Metal Protection Tube Use:

√ Carefully select the proper protection tube alloy for your process to maximize the service life. √ Use a thick walled tube, such as schedule 80, double extra heavy, or Richards heavy duty SP size for longer service life. √ Use a thin walled tube such as schedule 40, or smaller O.D. tube if you require a quicker response time. √ If the protection tube will be subject to severe mechanical shock or abrasion, use the Richards heavy duty SP size.

√ Protection tubes should be inserted into fluids a minimum of six times the O.D. of the tube. √ Protection tubes should be inserted into gases a minimum of eight times to the O.D. of the tube. √ Insertion lenghts for furnaces and salt baths are typically a minimum of 6 inches (152.4 mm).

√ Protection tubes, which pass through a hot zone (muffle furnace), should be inserted at least 12 inches (304.8 mm). √ In molten salt baths, angle assembilies tube lengths should be a minimum of 18” to protect the elbow from level changes. √ If the elbow on angle asseblies will be subjected to high temperatures, an all alloy bent type tube should be used. √ Replace all metal protection tubes on a regular basis, since they will become porious over time. √ Never shorten the life of new thermocouple elements by placing them into old, worn-out, porious, protection tubes. √ Protection tube overall lengths should be long enough to insure that the head temperature will not exceed 400°F or 204°C . √ Use large O.D., or thick walled protection tubes where sagging is a problem at elevated temperatures. √ Note that metal tubes are somewhat porious above 1500°F or 815°C , so in some cases a ceramic inner is also used.

Pipe Size Dimension Chart

NPT

Standard Weight

Extra Heavy Weight

Schedule 160

Double Extra Heavy

Pipe size

O.D. Inch

O.D. mm

I.D. Inch

Wall Inch

I.D. mm

Wall mm

I.D. Inch

Wall Inch

I.D. mm

Wall mm

I.D. Inch

Wall Inch

I.D. mm

Wall mm

I.D. Inch

Wall Inch

I.D. mm

Wall mm

1/8”

.41

.27

.068

6.9

1.7

.22

.095

5.6

2.4

-

-

-

-

-

-

-

-

10.4

13.7

1/4”

.54

.36

.088

9.1

2.2

.30

.119

7.6

3.0

-

-

-

-

-

-

-

-

17.2

3/8”

.68

.49

.091 12.4

2.3

.42

.126 10.7

3.2

-

-

-

-

-

-

-

21.3

1/2”

.84

.62

.109 15.7

2.8

.56

.147 14.0

3.7

.466 .187 11.8

4.7

.25

.29

6.4

7.4

26.7

3/4”

1.05

.82

.113 20.8

2.9

.74

.154 18.8

3.9

.614 .218 15.6

5.5

.43

.31 10.9 7.9

33.5 1.05 .133 26.7

1”

1.32

3.4

.96

.179 24.4

4.5

.815 .250 20.7

6.4

.60

.36 15.2 9.1

42.2 1.38 .140 35.1

1 1/4”

1.66

3.6

1.28 .191 32.5

4.9

1.16 .250 29.5

6.4

.90

.38 22.8 9.7

48.3 1.61 .145 40.9

1 1/2”

1.90

3.7

1.50 .200 38.1

5.1

1.34 .281 34.0

7.1

1.10 .40 27.98 10.2

60.3 2.07 .154 52.6

2”

2.38

3.9

1.94 .218 49.3

5.5

1.69 .343 42.9

8.7

1.50 .44 38.1 11.2

2 12”

2.88

73.0 2.47 .203 62.7

5.2

2.32 .276 59.0

7.0

2.13 .375 54.1

9.5

1.77 .55 45.0 14.0

3”

3.50

88.9 3.07 .216 77.9

5.5

2.90 .300 73.7

7.6

2.62 .438 66.5 11.1 2.30 .60 58.4 15.2

3 1/2”

4.00 101.6 3.55 .226 90.1

5.7

3.36 .318 85.4

8.1

-

-

-

-

2.73 .64 69.3 16.3

4”

4.50 114.3 4.03 .237 102.3 6.0

3.83 .337 97.2

8.6

3.44 .531 87.4 13.5 3.15 .67 80.1 17.0

5”

5.56 141.3 5.04 .258 128.0 6.6

4.81 .375 122.1 9.5

4.31 .625 109.4 15.9 4.06 .75 103.1 19.0

6”

6.63 168.3 6.07 .280 154.2 7.1

5.77 .432 146.6 10.7 5.19 .719 131.8 18.3 4.91 .86 124.7 21.8

8”

8.63 219.1 7.99 .322 202.9 8.2

7.63 .500 193.8 12.7 6.82 .906 173.2 23.0 6.87 .88 174.5 22.4

10”

10.75 273.1 10.02 .365 254.5 9.3

9.56 .594 242.8 15.1 8.50 1.125 215.9 28.6 8.75 1.00 222.3 25.4

12” 12.75 323.9 11.94 .406 303.3 10.3 11.37 .688 288.8 17.5 10.1 1.312 257.3 33.3 9.94 1.00 252.4 25.4

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