Alumina thermocouple protection tubes
One-end-closed and open-ended ceramic sheaths that protect thermocouples in temperature-measurement instruments and industrial furnaces.
Trusted by 100+ industrial customersTrusted by 100+ customers, from wafer makers to thermocouple makers
21 million alumina tubes shipped since 1984.
Half a million pieces a year from our own kilns in Tangshan, China. Standard sizes usually ship from stock in 3–7 days.
- Compound semiconductors
- Thermocouples
- Specialty glass
- Industrial furnaces
- Metallurgy
- Research labs
100+ repeat customers1.4 million+ pieces shipped since 2024View all customers
Key facts
- Certified quality system for thermocouple protection tubes
- ISO 9001:2015
- Lab-tested alumina tube sample (report 26-04928)
- 99.61% Al₂O₃
- Standard sizes usually ship from stock
- ~3–7 days
- Usual minimum order for custom parts
- 100 pcs
- Samples for approval
- 5–10 pcs
Products
Five product families for sensor, furnace and laboratory buyers.
Protection tubes lead the range. The same materials and forming lines make the insulators, furnace tubes, crucibles and special-shaped parts that go around them.
Alumina thermocouple insulators and multi-bore tubes
Single-, double- and multi-bore insulators that separate thermocouple wires and provide electrical insulation at high temperature and high frequency.
High-temperature alumina and corundum furnace tubes
Open-ended process tubes, large-diameter tubes and custom tubes for laboratory, resistance, electric and heat-treatment furnaces.
Alumina and corundum crucibles and boats
Cylindrical, rectangular and special-shaped crucibles and boats for metallurgy, chemical processing, electronics, glass and laboratory analysis.
Custom alumina and industrial ceramic components
Special-shaped parts made from your drawing or sample, by slip casting, pressing, extrusion or hot pressing.
Also made
- Alumina, corundum, and industrial ceramic tubing
- Ceramic balls, jars, and related mill components
- Textile wear and friction ceramics
- Electrical, heating, and lamp-base ceramics
- Ceramic rollers and screening components
Track record
Industrial volumes, and customers who keep coming back.
- customers served
- 100+
- repeat customers
- 100+
- pieces shipped, 2024–2026
- 1.4 million+
- alumina tubes shipped since 1984
- 21 million
We supplied thermocouple protection tubes for the expansion of China’s solar industry.
Pieces shipped 2024–2026: from our sales records.
Where our ceramics work
Compound-semiconductor crystal growth
Several substrate makers. This is our largest product line.
What we supply
Flat and round twin-bore insulators, 1.2 m and longer, made to drawing
Temperature measurement
10+ thermocouple and instrument makers
What we supply
Closed-end protection tubes, 1- to 4-bore insulators and insulator beads
Optical glass and advanced alloys
Optical-glass and specialty-alloy producers
What we supply
Open-ended corundum tubes, insulators and parts made to drawing
How we make it
From alumina powder to a packed crate, in one factory.
Milling, forming, firing, finishing, inspection and packing all happen in our own factory in Tangshan.
02Milling
The powder is milled in large drum ball mills.
05Firing
Tubes hang vertically in the kiln, and our written gas-kiln procedure controls firing with thermocouples and an optical pyrometer.
06Finishing
Tubes are cut to the ordered length, then slotted or drilled where the drawing calls for it.
07Inspection
Outside and inside diameters are measured with vernier calipers.
Who we supply
Trusted across industries.
What each kind of customer orders from us.
01
Compound-semiconductor substrate makers
Long flat and round twin-bore insulators for their crystal-growth furnaces.
02
Thermocouple and temperature-instrument makers
Protection tubes and multi-bore insulators, with repeat orders every few weeks.
03
Optical-glass and specialty-alloy producers
Corundum tubes and insulators for melting, annealing and heat-treatment furnaces.
04
Furnace builders, steel and metallurgy plants
Furnace work tubes, drilled and threaded tubes, and parts made to drawing.
05
Research institutes and laboratories
Crucibles and boats, insulators and tubes.
06
Export partners
Our tubes and insulators are in use in Europe and South Korea through export partners.
Made to your drawing
Send the drawing you already have. We form the part to it.
We design from customer drawings or samples, and make special-shaped parts by four forming routes. Tell us the dimensions and operating conditions; we propose the material and route.
Forming methods
- Slip casting
- Pressing
- Extrusion
- Hot pressing
Geometries
- Round tube
- Elliptical tube
- Square tube
- Open-ended through tube
- One-end-closed protection tube
- Single-bore tube
- Double-bore tube
- Multi-bore tube
- Capillary tube
- Perforated tube
- Threaded tube
- Ribbed or prismatic tube
- Solid rod
- Crucible
- Boat
- Ball
- Custom-shaped component
- alumina tubes shipped
- 21 million
- pieces a year from our own kilns
- ~500,000
- Certified quality system for thermocouple protection tubes
- ISO 9001:2015
Certified and tested
ISO 9001 certified for protection tubes, and tested by an independent lab.
Our quality management system is certified to ISO 9001:2015 for making ceramic protection tubes for thermocouples. An alumina tube sample tested at 99.61% Al₂O₃.
Quality management
ISO 9001:2015
GB/T19001-2016 · certified by CFL Certification Center
- Scope
- Manufacturing of ceramic protective tubes for thermocouples
- Registration
- 06525Q02034R1S
- Valid
- 6 August 2025 – 5 August 2028
- Accreditation
- CNAS C065-M · IAF
The issuer listed this certificate as valid when checked on 6 October 2026. Check the issuer’s record (Chinese).
A copy of the certificate is available on request.
Independent lab test
99.61% Al₂O₃
Alumina tube sample, tested by Chinalco Testing Technology (Zhengzhou) Co., Ltd., 13 May 2026. Report 26-04928.
| Item | % | Method |
|---|---|---|
| Al₂O₃ | 99.61 | GB/T 24487-2022 |
| SiO₂ | 0.15 | GB/T 6609.3-2004 |
| Fe₂O₃ | 0.014 | GB/T 6609.4-2004 |
| Na₂O | 0.054 | GB/T 6609.1-2018 |
| CaO | 0.13 | GB/T 6609.1-2018 |
| Loss on ignition | 0.033 | GB/T 6609.2-2022 |
Tested by the same lab every year
- 202499.55% Al₂O₃, report 24-04372
- 202599.57% Al₂O₃, report 25-04979
- 202699.61% Al₂O₃, report 26-04928
Lab reports are available on request.
Packing
Crated, strapped and palletised before it leaves the factory.
- 01Foam-lined plywood crates on skids, strapped
- 02Tubes bubble-wrapped or bundled in stretch film
- 03Small insulators in 1 kg bags
- 04Numbered crates strapped on pallets
Tell us your destination and handling needs; we confirm packing and marking per order.
Request a quote
Send us a drawing, a sample or a part number.
Tell us the dimensions, grade and quantity. We confirm the grade, dimensions and tolerances in each quotation. Our yearly lab reports are available on request.
- Custom parts, usually from
- 100 pcs
- Samples for approval
- 5–10 pcs
- Production, usually
- 25–30 days
- Standard sizes from stock, small to bulk orders
- ~3–7 days