Protection tubes

Protection tubes

Metal, ceramic, SiC, silicon nitride, APMT and sapphire tubes. Choose the material for your temperature and atmosphere to extend sensor life.

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Ceramic & SiC tubes

C610 and C799 ceramic tubes are gas-tight and corrosion resistant; SiC tubes withstand thermal shock and abrasion. Two- and four-bore ceramic insulators are also available.

High-purity materials have the least effect on platinum thermocouple EMF at 1300 °C

Maximum length: Ceramic 3500 mm, SiC 2100 mm
Ceramic insulators: 2- and 4-bore ceramic insulators, Ø1.1 ~ 18 mm

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Silicon nitride tubes

Silicon nitride is a very strong structural ceramic with excellent thermal stability and resistance to oxidation, acids, alkalis and molten non-ferrous metals, outperforming refractories and recrystallised SiC.

High strength, wear and thermal-shock resistance
Hardness HRA 92–94

Material: Si₃N₄ ≥ 99 %
Flexural strength: 800 ~ 1000 MPa
Thermal conductivity: 22 ~ 24 W/m·K
Thermal expansion: 1.0 × 10⁻⁶ /°C (RT ~ 1000 °C)
Maximum temperature: 1200 °C in air
Hardness: HRA 92 ~ 94
Sizes: 16 × 8 ~ 60 × 40 mm, L 200 ~ 1500 mm

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APMT protection tubes

KANTHAL® APMT is a powder-metallurgy FeCrAlMo alloy with high thermal conductivity, mechanical strength and high-temperature corrosion resistance, rated for long-term use at 1250 °C.

Excellent oxidation resistance; no sagging like conventional metal tubes
Non-spalling alumina scale keeps furnaces clean and maintenance-free
Resists sulphidation and carburisation; thin walls for fast response

Material: Kanthal® APMT (FeCrAlMo)
Maximum temperature: 1250 °C

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Sapphire tubes

Single-crystal alumina with a completely uniform, pore-free structure. It lasts several times longer than ceramic and can be used up to 2000 °C.

100 % gas-tight and pressure resistant
Excellent chemical resistance and biocompatibility
Keeps its shape at high temperature

Material: Single-crystal Al₂O₃
Maximum temperature: 2000 °C
Melting point: 2053 °C
Hardness: Mohs 9

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PROTECTION TUBES

Models

Metal protection tubes

Material	Normal use	Melting point	Atmosphere
304SS	900 °C	1400 °C	O R N V
310SS	1150 °C	1400 °C	O R N V
316SS	930 °C	1370 °C	O R N V
321SS	870 °C	1398 °C	O R N V
347SS	870 °C	1426 °C	O R N V
446SS	1090 °C	1482 °C	O R N V
Carbon steel	700 °C	1370 °C	O N
Inconel	1150 °C	1398 °C	O N V
Inconel X	1200 °C	1438 °C	O N V
Incoloy	870 °C	1370 °C	O N
Hastelloy X	1200 °C	1288 °C	O
Hastelloy C	980 °C	1266 °C	O
Hastelloy B	760 °C	1300 °C	O R
Monel	540 °C	1349 °C	O R
Brass	340 °C	1010 °C	O
Aluminium	370 °C	649 °C	O
Nickel	760 °C	1452 °C	O
Tantalum	2700 °C	2996 °C	V
Titanium	1100 °C	1668 °C	V N
Pt-10 % Rh	1600 °C	1850 °C	O

N: neutral V: vacuum B: sulphur corrosion O: oxidising R: reducing

Ceramic and SiC tubes

Material	Working temp.	OD × ID	Max. length
C610 (60 % Al₂O₃)	1500 °C	Ø0.8 × 0.3 ~ Ø30 × 23 mm	3500 mm
C799 (99.7 % Al₂O₃)	1700 °C	Ø0.8 × 0.3 ~ Ø30 × 23 mm	3500 mm
SiC (70)	1400 °C	Ø17 × 12 ~ Ø50 × 25 mm	2000 mm
Recrystallised SiC	1600 °C	Ø18 × 10 ~ Ø50 × 38 mm	2100 mm
Self-bonded SiC	1350 °C	Ø18 × 13 ~ Ø45 × 35 mm	2100 mm

PROTECTION TUBES

Full product list

18 products, grouped by type. Specifications as published by Thermoway; custom versions available on request.

Metal Tubes

Metal Tubes_Thermowell

Protection Tube (for screwing Hexagon Socket Head Cap Screws): General Outside Diameter: 6.4φ, 8φ, 9.5φ, 10φ, 10.5φ, 12.7φ, 15.9φ, 17.3φ, 22φ

Protection Tube with Flange (Welded Tips): General Outside Diameter: 6.4φ, 8φ, 9.5φ, 10φ, 10.5φ, 12.7φ, 15.9φ, 17.3φ, 22φ

Protection Tube Made by Solid Tube (Max. Length = 1500 mm): General Outside Diameter: 12φ, 15φ, 17φ, 22φ

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MPA High Temp. Protection Tube 1350°C

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Ceramic Tubes

Ceramic Tubes (1)

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Ceramic Tubes (2)

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SiC Tubes

SIC Tubes

Comparison of five SiC tube types
C610: inside diameter 0.8X0.3; outside diameter 30X23; max length 3500 mm; advantages: good gas tightness; disadvantages: low thermal shock resistance; max operating temperature 1700℃
C799: inside diameter 0.8X0.3; outside diameter 30X23; max length 3500 mm; advantages: good gas tightness, wear and corrosion resistance, heat resistance; disadvantages: medium thermal shock resistance; max operating temperature 1900℃
SIC(70): inside diameter 17X12; outside diameter 50X25; max length 2000 mm; advantages: strong thermal shock resistance, high conductivity; disadvantages: low gas tightness; max operating temperature 1650℃

More specifications

Recrystallization SIC Tube: inside diameter 18X10; outside diameter 50X38; max length 2100 mm; advantages: strong thermal shock resistance, wear and corrosion resistance; disadvantages: low gas tightness; max operating temperature 1650℃
Self-combine SIC Tube: inside diameter 18X13; outside diameter 45X35; max length 2100 mm; advantages: strong thermal shock resistance, wear and corrosion resistance; disadvantages: low gas tightness; max operating temperature 1500℃

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Teflon Tubes

Teflon Tubes with Flange

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Quartz Tubes

Abrasion Resistant and High Temperature Tubes

Sapphire Protection Tube

Synthetic sapphire is a pure, defect-free aluminum oxide single crystal. Unlike sintered corundum ceramics it has no grain boundaries where corrosion starts, so it is several times more durable than conventional ceramic thermocouple tubes and in some uses comparable to platinum-coated sheaths

Uniform structure prevents surface outgassing

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Silicon Nitride Protection Tube

Silicon nitride (Si3N4), a compound of silicon and nitrogen first synthesized in 1857, is a structural ceramic refractory with high hardness and strength; hot-pressed sintered silicon nitride is among the hardest substances in the world; Excellent thermal stability, oxidation resistance, acid and alkali resistance, and resistance to non-ferrous metal erosion; may be a better choice than general refractory materials and recrystallized SiC tubes; Thermal conductivity with a low thermal expansion coefficient over a wide temperature range gives excellent thermal shock resistance for high-durability, high-temperature environments
Highlights: High Strength x Super Resistant to Abrasion x Thermal Shock Resistance

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APMT High Temperature Protection Tube

A ferritic iron-chromium-aluminum alloy tube (FeCrAlMo alloy) manufactured by advanced powder metallurgical technology, with high thermal conductivity, high mechanical strength and excellent high-temperature corrosion resistance; withstands prolonged temperature up to 1250 °C (2280 °F). APMT gives design engineers options in applications previously considered the domain of ceramic materials, and solves the problems of conventional nickel-based alloys.; Superior oxidation properties, sagging problem solution: alumina-forming alloys have superior resistance to oxidation compared to conventional chromia-forming NiCr and FeNiCr alloys
Clean and maintenance free in operation: the protective alumina film resists spalling during thermal cycling, so it will not contaminate products in the furnace or cause electrical short circuits in heating elements installed inside APMT tubes; no maintenance during operation means fewer production stoppages
Applications: mainly heat treatment, steel and aluminum industries; radiant tubes in electrically or gas fired furnaces (continuous annealing and galvanizing furnaces, seal quench furnaces, holding and dosing furnaces in the aluminium, zinc and lead industries), thermocouple protection tubes, furnace muffles for sintering

More specifications

Protection tubes for thermocouples: long record of successful installation up to 1250 °C, some installations up to 1400 °C with special design. Advantages: high resistance to sulphur compounds and carburization; thin walls with long service life give rapid heat transmission and higher sensitivity; aluminum oxide layer has minimal tendency to spall, avoiding contamination; no short-circuit risk since aluminum oxide is not electrically conductive; Contact us for more product information

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253 High Temp. Protection Tubes

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UMCO Abrasion Resistant Protection Tubes

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INCO High Temp. Protection Tubes

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Ceramic Insulators

Ceramic Insulators Specification
C610 (2 Holes): Min. Outside Diameter 1.2ψ, Hole OD 0.2ψ; Max. Outside Diameter 16ψ, Hole OD 4.9ψ; Max. Length 3500 mm
C610 (4 Holes): Min. OD 1.5ψ, Hole OD 0.3ψ; Max. OD 16ψ, Hole OD 4.6ψ; Max. Length 3500 mm
C799 (2 Holes): Min. OD 1.1ψ, Hole OD 0.3ψ; Max. OD 18ψ, Hole OD 4.0ψ; Max. Length 3500 mm

More specifications

C799 (4 Holes): Min. OD 1.5ψ, Hole OD 0.3ψ; Max. OD 15ψ, Hole OD 3.6ψ; Max. Length 3500 mm

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High Temperature Exotic Protection Tube

Max operation temperature by material — Metal: APMT 1350℃; APM 1350℃; Molybdenum 2300℃; Tungsten 2500℃; Tantalum 2200℃; Incoloy 800 1050℃; UMCO50 1150℃
Non-metal: Sapphire 2000℃; Silicon Nitride 1200℃; Sialon 1300℃

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CATALOG

Ceramic & SiC tubes

Silicon nitride tubes

APMT protection tubes

Sapphire tubes

Models

Metal protection tubes

Ceramic and SiC tubes

Full product list

Metal Tubes

Metal Tubes_Thermowell

MPA High Temp. Protection Tube 1350°C

Ceramic Tubes

Ceramic Tubes (1)

Ceramic Tubes (2)

SiC Tubes

SIC Tubes

Teflon Tubes

Teflon Tubes with Flange

Quartz Tubes

Quartz Tube (4)

Quartz Tube (3)

Quartz Tube (2)

Quartz Tube (1)

Abrasion Resistant and High Temperature Tubes

Sapphire Protection Tube

Silicon Nitride Protection Tube

APMT High Temperature Protection Tube

253 High Temp. Protection Tubes

UMCO Abrasion Resistant Protection Tubes

INCO High Temp. Protection Tubes

Ceramic Insulators

Ceramic Insulators

High Temperature Exotic Protection Tube

High Temperature Exotic Protection Tube

Other product categories

New products

Thermocouples

Resistance temperature detectors (RTD)

Explosion-proof thermocouples

MI sheathed thermocouples

Thermocouple wire

Connectors, heads & fittings

Semiconductor

Extreme high-temperature thermocouples

Temperature transmitters

INOR products

OMEGA products

Surface temperature

Reference standards & welder

Dial thermometers

Recorders, calibrators & thermometers

Heaters & heating elements

Tools & equipment

Special applications

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