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Tyco Electronics Corporation
300 Constitutional Drive
Menlo Park, CA 94025 USA
Specification
This Issue:
Date:
Replaces:
RT-375
Issue 7
4 February 2004
Issue 6
THERMOFIT® RT-375 TUBING
Fluoropolymer, Semi-Flexible, Clear, Flame Resistant, Heat-Shrinkable
1. SCOPE
This specification covers the requirements for one type of flexible, flame resistant, electrical insulating,
extruded tubing whose diameter will reduce to a predetermined size upon the application of heat in excess of
150°C (302°F). The tubing shall be flame resistant and shall be clear.
2. APPLICABLE DOCUMENTS
This specification takes precedence over documents referenced herein. Unless otherwise specified, the latest
issue of referenced documents applies. The following documents form a part of this specification to the
extent specified herein.
2.1 GOVERNMENT-FURNISHED DOCUMENTS
Federal
O-S-1926 Sodium Chloride, Technical
Military
MIL-H-5606 Hydraulic Fluid, Petroleum Base, Aircraft, Missile and Ordnance
MIL-T-83133 Turbine Fuel, Aviation, Grade JP-8
MIL-L-7808 Lubricating Oil, Aircraft Turbine Engine, Synthetic Base
MIL-A-8243 Anti-icing and Deicing - Defrosting Fluid
MIL-L-23699 Lubricating Oil, Aircraft Turbine Engines, Synthetic Base
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2.2 OTHER PUBLICATIONS
American Society for Testing and Materials (ASTM)
D 2671 Standard Methods of Testing Heat-Shrinkable Tubing for Electrical Use
(Copies of ASTM publications may be obtained from the American Society for Testing and Materials, 1916
Race Street, Philadelphia, Pennsylvania 19103 or via the ASTM website at
http://www.astm.org).
International Organization for Standardization (ISO)
ISO 846 Plastics – Evaluation of the action of Microorganisms
(Copies of ISO publications may be obtained from the International Organization for Standardization, 1, rue
de Varembé, CH-1211 Geneva 20, Switzerland or via the ISO website at
http://www.iso.ch/iso/en/ISOOnline.frontpage)
SAE International
AMS-DTL-23053 Insulating Sleeving, Electrical, Heat Shrinkable, General Specification for
(Copies of SAE publications may be obtained from SAE International, 400 Commonwealth Drive,
Warrendale, PA 15096-0001 or via the SAE website at http://www.sae.org.)
3. REQUIREMENTS
3.1 MATERIALS
The tubing shall be fabricated from thermally stabilized, modified fluoropolymer and shall be crosslinked by
irradiation. It shall be homogeneous and essentially free from flaws, defects, pinholes, bubbles, seams,
cracks, and contaminants.
3.2 PROPERTIES
The tubing shall meet the requirements of Table 3.
4. QUALITY ASSURANCE PROVISIONS
4.1 CLASSIFICATION OF TESTS
4.1.1 Qualification Tests
Qualification tests are those performed on tubing submitted for qualification as a satisfactory product and
shall consist of all tests listed in this specification.
SPECIFICATION RT-375 ISSUE 7 Page 3
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4.1.2 Acceptance Tests
Acceptance tests are those performed on tubing submitted for acceptance under contract. Acceptance tests
shall be:
Dimensions
Longitudinal Change
Concentricity
Tensile Strength
Ultimate Elongation
Secant Modulus
Low Temperature Flexibility
Flammability
Heat Shock
Clarity Stability
Statistical process control data may be used to demonstrate conformance for dimensions.
4.2 SAMPLING INSTRUCTIONS
4.2.1 Qualification Test Samples
Qualification test samples shall consist of 50 feet (15 m) of tubing. Qualification of any size within each size
range specified below shall qualify all sizes within that size range.
Range of Sizes
3/64 through 1/4
3/8 through 2
4.2.2 Acceptance Test Samples
Acceptance test samples shall consist of not less than 16 feet (5 m) of tubing selected at random from each
compound batch or the first sleeving production lot of the batch compound. Physical property tests
performed at this time qualify subsequent sleeving lots produced from the same compound batch.
4.2.3 Lot Formation
A lot shall consist of all tubing of the same size, from the same production run, and offered for inspection at
the same time.
4.3 TEST PROCEDURES
Unless otherwise specified, perform tests on specimens which have been fully recovered by conditioning for
3 minutes in a 200 ± 5°C (392 ± 9°F) oven. Condition the test specimens (and measurement gauges, when
applicable) for 3 hours at 23 ± 3°C (73 ± 5°F) and 50 ± 5 percent relative humidity prior to all testing. Use
mechanical convection type ovens in which air passes the specimens at a velocity of 100 to 200 feet (30 to 60
m) per minute.
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4.3.1 Low Temperature Flexibility
For tubing of expanded diameter less than 1/4 inch (6 mm), cut three tubular specimens, 12 inches (300 mm)
long, from the expanded tubing. For tubing of expanded diameter 1/4 inch (6 mm) or greater, cut three strip
specimens, 1/4 inch (6 mm) wide and 12 inches (300 mm) long, from the expanded tubing. Recover the
specimens in accordance with Section 4.3 and condition with appropriate mandrels for 4 hours at -55 ± 2°C
(-67 ± 4°F). The mandrel diameter shall be 10 times the specimen thickness, ± 10 percent. For tubular
specimens, the specimen thickness shall be equivalent to the outside diameter. While at the specified
temperature, and without removing the specimens from the cold chamber, wrap the specimens 360° around
the mandrel in approximately 2 seconds. Disregard any side cracking, caused by flattening of the specimens
on the mandrel.
4.4 REJECTION AND RETEST
Failure of any sample of tubing to conform to any one of the requirements of this specification shall be cause
for rejection of the lot represented. Tubing which has been rejected may be replaced or reworked to correct
the defects and resubmitted for acceptance. Before resubmitting, full particulars concerning previous
rejection and action taken to correct the defects shall be furnished to the inspector.
5. PREPARATION FOR DELIVERY
5.1 FORM
The tubing shall be supplied on spools, unless otherwise specified.
5.2 PACKAGING
Packaging shall be in accordance with good commercial practice.
5.3 MARKING
Each container of tubing shall be permanently and legibly marked with the size, quantity, manufacturer's
name, product name, and lot number.
SPECIFICATION RT-375 ISSUE 7 Page 5
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TABLE 1
Tubing Dimensions
As Supplied As Recovered
Inside Diameter Inside Diameter Wall Thickness
Size Minimum Maximum Minimum Maximum Nominal
in.
mm. in. mm. in. mm. in. mm. in. mm.
3/64 .046 1.17 .023 0.58 .008 0.20 .012 0.30 .010 0.25
1/16 .063 1.60 .031 0.79 .008 0.20 .012 0.30 .010 0.25
3/32 .093 2.36 .046 1.17 .008 0.20 .012 0.30 .010 0.25
1/8 .125 3.17 .062 1.57 .008 0.20 .012 0.30 .010 0.25
3/16 .187 4.74 .093 2.36 .008 0.20 .012 0.30 .010 0.25
1/4 .250 6.35 .125 3.17 .009 0.23 .015 0.38 .012 0.30
3/8 .375 9.50 .187 4.74 .009 0.23 .015 0.38 .012 0.30
1/2 .500 12.70 .250 6.35 .009 0.23 .015 0.38 .012 0.30
3/4 .750 19.05 .375 9.50 .014 0.36 .020 0.51 .017 0.43
1 1.000 25.40 .500 12.70 .016 0.41 .022 0.56 .019 0.48
1-1/2 1.500 38.10 .750 19.05 .017 0.43 .023 0.58 .020 0.51
2 2.000 50.80 1.000 25.40 .017 0.43 .023 0.58 .020 0.51
TABLE 2
Mandrel Dimensions for Bend Testing
Tubing Size Mandrel Diameter
in. mm.
3/64 to 1/4 inclusive 5/16 ± 0.002 7.9 ± 0.05
3/8 to 1/2 inclusive 3/8 ± 0.003 9.5 ± 0.08
3/4 to 2 inclusive 7/16 ± 0.004 11.1 ± 0.10
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TABLE 3
Requirements
PROPERTY UNIT REQUIREMENT TEST METHOD
PHYSICAL
Dimensions
Inches (mm)
In accordance with Table 1
ASTM D 2671
Longitudinal Change Percent +0, -10 Note 1
Tensile Strength psi (MPa) 3500 (24.1) minimum ASTM D 2671
Ultimate Elongation Percent 300 minimum Note 2
Concentricity (Expanded)
Sizes 3/64 through 1
Sizes 1-1/2 and 2
Percent
Percent
70 minimum
60 minimum
ASTM D 2671
Secant Modulus (Expanded) psi (MPa) 2.5 x 104 (172) minimum ASTM D 2671
Specific Gravity --- 1.90 maximum ASTM D 2671
Low Temperature Flexibility
4 hours at -55 ± 2°C (-67 ± 4°F)
--- No cracking Section 4.3.1
Heat Shock
4 hours at 250 ± 3°C (482 ± 5°F)
--- No dripping, flowing or cracking Table 2
ASTM D 2671
Heat Resistance
336 hours at 225 ± 3°C (437 ± 5°F)
Followed by test for:
ASTM D 2671
Ultimate Elongation Percent 100 minimum
Clarity Stability
24 hours at 200 ± 3°C (392 ± 5°F)
--- Marking legible through tubing
wall
AMS-DTL-23053
ELECTRICAL
Dielectric Strength
Volts/mil
(volts/mm)
400 (15,760) minimum
ASTM D 2671
Note 3
Volume Resistivity ohm-cm 1011 minimum ASTM D 2671
CHEMICAL
Copper Mirror Corrosion
16 hours at 160 ± 2°C (320 ± 4°F)
---
Noncorrosive
ASTM D 2671
Procedure A
Copper Contact Corrosion
16 hours at 160 ± 2°C (320 ± 4°F)
--- No pitting or blackening of
copper
ASTM D 2671
Procedure B
Flammability --- Self-extinguishing within
1 minute, 25% maximum flag
burn
ASTM D 2671
Procedure C
Fungus Resistance
Followed by tests for:
Tensile Strength
Ultimate Elongation
Dielectric Strength
psi (Mpa)
percent
Volts per mil
(volts per mm)
3500 minimum (24.1)
300 minimum
400 minimum (15,760)
ISO 846 Method B
Note 2
ASTM D 2671
ASTM D 2671
Water Absorption
24 hours at 23 ± 3°C (73 ± 5°F)
Percent 0.5 maximum ASTM D 2671
SPECIFICATION RT-375 ISSUE 7 Page 7
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TABLE 3
Requirements (continued)
PROPERTY UNIT REQUIREMENT TEST METHOD
Fluid Resistance
24 hours at 50 ± 3°C (122 ± 5°F) in:
JP-8 Fuel (MIL-T-83133)
Hydraulic Fluid (MIL-H-5606)
Lubricating Oil, (MIL-L-23699)
Lubricating Oil, (MIL-L-7808)
5% NaCl, O-S-1926
De-icing Fluid (MIL-A-8243)
Water
Followed by tests for:
--- --- ASTM D 2671
Note 4
Tensile Strength psi (MPa) 2000 (13.8) minimum
Ultimate Elongation Percent 250
Dielectric Strength Volts/mil
(volts/mm)
400 (15,760) minimum
NOTE 1: Condition the specimens for 3 minutes at 200 ± 3°C (392 ± 5°F) and cool to room temperature before final
measurements.
NOTE 2: Use 1-inch (25.4-mm) bench marks, 1-inch (25.4-mm) initial jaw separation, and 2 ± .2-inch (50 ± 5-mm) jaw
separation speed.
NOTE 3: Recover the specimens on the metal mandrels for 10 minutes, minimum, at 175 ± 2°C (347 ± 4°F) or until the
tubing is completely shrunk on the mandrels.
NOTE 4: To measure the dielectric strength, immerse the recovered specimens in the fluids prior to inserting the
mandrels into the wiped and dried specimens.
