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GY AluminaProtection Tubes · Insulators · Crucibles
A wide stack of ivory tubes with rounded closed ends, grouped in bundles wrapped with clear stretch film, on a plain grey background.

Alumina thermocouple protection tubes

One-end-closed and open-ended ceramic sheaths that protect thermocouples in temperature-measurement instruments and industrial furnaces.

Request a quoteSizes we have produced

Configurations

  • One-end closed
  • Open-ended
  • Round
  • Elliptical
A finished thermocouple held in a hand: a grey connection head on a metal sheath that ends in a long white ceramic protection tube.
Fitted to a thermocouple.
LODIDclosed endopen end

Applications

  • Thermocouple assemblies
  • Temperature-measurement instruments
  • Industrial furnaces
  • Heat-treatment furnaces

Ordering

Minimum order, non-standard parts
100 pcs
Usually, per item made to your drawing or sample.
Samples for approval
5–10 pcs
Usually sent for you to approve before the order runs.
Production lead time
25–30 days
Usual production cycle for non-standard parts.
Standard sizes from stock
~3⁠–⁠7 days
Stock covers most standard sizes. Small orders ship in about 3 days, bulk orders in about 7 days.

Typical terms. Quantities and dates for your order are confirmed in its quotation.

Sizes we have produced

Type
One end closed
OD
10–30 mm
Length
530–1000 mm

Other sizes made to drawing; tolerances confirmed per quotation.

Examples, in mm

Sizes produced for Alumina thermocouple protection tubes, in millimetres
ODIDLengthNote
107530
24—1000
2618530
3024995Drilled

As marked by the factory on stock labels, packing and photos. A dash means the label gave no inside diameter.

Secondary operations

Done in the factory after forming. Hole sizes and positions are confirmed from your drawing.

  • Cut to lengthTubes cut to the ordered length.
  • End slotsA slot across a closed tip, or slots cut into open tube and insulator ends.
  • Side holes and perforated tubesOne or two side holes, or a line of holes along the tube.
  • Closed ends with drilled holesOne-end-closed tubes drilled along their length.

Photographed at the factory

About fifty long ivory tubes with rounded closed ends, standing in two groups against a white grooved wall.
A wide stack of ivory tubes with rounded closed ends, grouped in bundles wrapped with clear stretch film, on a plain grey background.
Film-wrapped bundles of ivory closed-end tubes; each domed tip is cut with a single straight slot.
Long ivory tubes with rounded closed ends standing side by side, each with a single line of small holes along its length.

Materials and grades

High-alumina (>85% Al₂O₃), corundum (99, 99.5 and 99.7% Al₂O₃ grades) and mullite. Purity and maximum temperature are confirmed per SKU.

Full datasheets for both grades
Material grades for Alumina thermocouple protection tubes
MaterialAl₂O₃ %Working temperature °CHardness, Mohs
High-alumina>851300–14508
Corundum99 / 99.5 / 99.7*1600–1800*8-9
MulliteData supplied with quotation

* Stated per SKU. Not every corundum product is 99.7% Al₂O₃ or suitable for 1800 °C; the grade and maximum temperature of each part are confirmed in its quotation.

Certified and tested

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

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.

Chemical composition of the tested alumina tube sample
Item%Method
Al₂O₃99.61GB/T 24487-2022
SiO₂0.15GB/T 6609.3-2004
Fe₂O₃0.014GB/T 6609.4-2004
Na₂O0.054GB/T 6609.1-2018
CaO0.13GB/T 6609.1-2018
Loss on ignition0.033GB/T 6609.2-2022

Result for the submitted sample. Each quotation comes with test data for the grade you order.

What to send for a quote

  1. 01Outside diameter (OD), inside diameter (ID) and length
  2. 02One end closed or both ends open
  3. 03Round or elliptical section
  4. 04Al₂O₃ grade, or your operating temperature and atmosphere
  5. 05Thermocouple type, if you want us to check the fit
  6. 06Quantity per order and expected reorder rhythm

Next family:Alumina thermocouple insulators and multi-bore tubes

Request a quote

Get a quotation for protection tubes.

Tell us the dimensions, grade and quantity. A contractual datasheet with current, product-specific test data and tolerances comes with each quotation.

Request a quotesales@gyalumina.com