Quartz Glass Tubes
Quartz glass tubes — also called fused quartz tubes, fused silica tubes, or quartz tubing — are high-purity amorphous SiO₂ cylinders used as furnace tubes, process chambers, CVD liners, reaction tubes, and high-temperature conduits where borosilicate glass cannot take the heat and metal would contaminate the process.
FGQuartz is a manufacturer of custom quartz glass tubes: OD 5–1000 mm, wall 0.5–20 mm+, length up to 3000 mm (longer by welded sections), SiO₂ ≥ 99.99%. Tubes are supplied plain-cut or fully fabricated — flanged, threaded, ported, bent, or welded — to your drawing, from a single prototype with no minimum order quantity.
Quick answer
What temperature can a quartz glass tube withstand? High-purity fused silica tubes run continuously to about 1200°C and briefly to about 1300°C. The material has no sharp melting point; it softens gradually near 1680°C. Thermal expansion is only about 5.5 × 10⁻⁷ /°C, so properly designed tubes survive rapid heating and cooling.
Key takeaways
- FGQuartz makes tubes from OD 5 mm to 1000 mm, wall 0.5–20 mm+, length to 3000 mm, to your drawing — there is no fixed SKU chart.
- Drawn tube, CNC machining, flame forming, welding, fire polishing, and annealing are done in one plant under one ISO 9001 system.
- Quartz resists HCl, HNO₃, H₂SO₄, aqua regia, and organic solvents, but is attacked by HF, hot concentrated phosphoric acid, and hot strong alkalis.
- Clear, UV (JGS1), IR (JGS3), and opaque fused silica are all available; the grade is chosen by application.
Written by the FGQuartz Engineering Team · Updated October 2026
On this page: Specifications · Material · Sizes · How to choose · Customization · Project examples · Applications · FAQ and quote
Lead time depends on size, grade, and drawing complexity; the quote confirms the schedule.
What quartz glass tubes are specified for
Product features
Quartz glass tube specifications
Technical specifications
Values below are FGQuartz published ranges for high-purity fused silica tubes. Critical dimensions and tolerances are set from the drawing and confirmed in design-for-manufacture (DFM) review.
| Parameter | Specification |
|---|---|
| Material | High-purity fused silica / fused quartz (SiO₂ ≥ 99.99%). Optical grades (JGS1 / JGS2 / JGS3) and opaque fused silica when specified. See JGS1 vs JGS2 vs JGS3. |
| Outer diameter (OD) | 5 mm – 1000 mm, including large-diameter process tubes. |
| Inner diameter (ID) | Specified with OD and wall thickness, or taken from the drawing. ID is not published as a separate catalog range. |
| Wall thickness | 0.5 mm – 20 mm+. Heavy-wall options for vacuum service. |
| Length | Up to 3000 mm as a standard run. Longer tubes by welded sections when required. |
| Dimensional tolerance | Critical dimensions and tolerances are set from the drawing and confirmed in DFM review. Concentricity / bow can be held to a tight class (e.g. < 0.1 mm/m) where specified. |
| Purity | SiO₂ ≥ 99.99%. Typical process-grade baseline: Al < 10 ppm, Fe < 5 ppm, Na+K < 5 ppm, total metals < 20 ppm. Trace metals and OH vary by grade. |
| Surface finish | As-drawn, fire-polished, or centerless-ground to the sealing / mating requirement on the drawing. |
| Shape | Straight drawn tubes; bent (U / L / custom radius); flanged; ported / manifold; multi-part welded assemblies. |
| End type | Plain cut, chamfered, fire-polished, flanged (fused or CNC-machined, including O-ring faces), threaded (external / internal), or sealed (domed or flat). |
| Processing | Diamond cutting, core drilling, CNC milling and slotting, centerless grinding, oxy-hydrogen flame forming and welding, fire polishing, annealing. |
| Customization | Build-to-print from DXF, STEP, IGES, or PDF. Single prototypes through production. No MOQ. |
Pressure. Quartz glass is much stronger in compression than in tension, so internal-pressure service depends on wall thickness, OD, length, and surface condition. Pressure rating is calculated per drawing — it is not a catalog number. Tell us the working pressure, temperature, and cycle with your enquiry.
Full thermal, mechanical, optical, and chemical tables: Technical Specifications.
Quartz glass, fused quartz, and fused silica
Material
In industrial purchasing, quartz glass, fused quartz, and fused silica all refer to amorphous high-purity SiO₂ (typically ≥ 99.99%). They are not three different products on a packing list — they are names for the same family of material. For a fuller explanation, see What is quartz glass?
The distinction that matters is feedstock. Fused quartz is melted from natural quartz crystal. Fused silica is synthetic, usually made from SiCl₄. Synthetic material is purer and more optically homogeneous; natural fused quartz is the usual workhorse for process tubes, boats, and crucibles.
Optical grades JGS1 (deep UV), JGS2 (UV–visible), and JGS3 (infrared) are selected by working wavelength. Standard process tubes typically use non-optical fused quartz unless a JGS grade is specified. Opaque fused silica is used when the tube is a thermal liner rather than an optical path.
Comparing quartz with ordinary laboratory glass? Read quartz glass vs borosilicate glass.
Typical properties of fused silica
Typical values for high-purity fused silica. Optical transmission and OH content vary by grade.
| Continuous service | 1200°C |
| Short-term maximum | 1300°C |
| Softening point | ≈ 1680°C |
| Annealing point | ≈ 1215°C |
| Strain point | ≈ 1120°C |
| Thermal expansion (20–300°C) | 5.5 × 10⁻⁷ /°C |
| Thermal conductivity (20°C) | ≈ 1.4 W/(m·K) |
| Density | ≈ 2.2 g/cm³ |
Melting point: amorphous fused silica has no sharp melting point; it softens gradually near 1680°C.
Chemical note: excellent resistance to HCl, HNO₃, H₂SO₄, aqua regia, and organic solvents. Attacked by HF, hot concentrated phosphoric acid, and hot strong alkalis.
Quartz tube sizes: made to drawing, not to a SKU chart
Available sizes
FGQuartz does not publish a standard OD × ID × wall stock list for quartz tubes. Custom sizes are manufactured according to customer drawings and application requirements, within the published range: OD 5–1000 mm, wall 0.5–20 mm+, length to 3000 mm.
Send OD and wall thickness (or OD and ID), length, and end details. If you are matching an existing tube, a sample or a dimensioned sketch is enough to start.
Size ranges and typical uses
| OD range | Typical uses | Points to specify |
|---|---|---|
| 5 – 25 mm | Thermocouple sheaths, small reaction and combustion tubes, lamp envelopes, gas feed lines. | OD and wall, length, closed or open end, any ground joint. |
| 25 – 150 mm | Laboratory tube furnaces, CVD reaction tubes, UV and heater sleeves, ported and bent process lines. | OD and ID, length, flange or thread, port positions, finish. |
| 150 – 1000 mm | Semiconductor diffusion and LPCVD tubes, solar POCl₃ diffusion tubes, large furnace chambers and liners. | OD, wall, length, sealing flange, support method, annealing and packing needs. |
Large-diameter tubes (up to OD 1000 mm) need support along their length and controlled heating, and are annealed and packed to suit their size. Ranges above are typical examples, not limits on what can be drawn.
How to choose a quartz glass tube
Selection guide
Start from the process condition, then match the grade, wall, and ends to it.
| If your process needs… | Specify |
|---|---|
| An optical path or UV exposure | Clear fused quartz or a JGS grade chosen by wavelength — see JGS1 vs JGS2 vs JGS3. |
| A thermal liner with no optical need | Opaque fused silica. |
| Vacuum or pressure service | Heavy wall (up to 20 mm+). Give the working pressure, temperature, and cycle so the wall can be calculated. |
| Fast heating and cooling | A thinner wall, which lowers the temperature gradient across it, and an annealed tube. |
| An O-ring or ground seal | A flanged tube, or a tube centerless-ground to the sealing OD. |
| Very low metallic contamination | A high-purity or synthetic fused silica grade, with trace-metal limits stated in the RFQ. |
| A hot zone longer than 3000 mm | Welded sections, post-weld annealed. |
| Contact with HF, hot phosphoric acid, or hot strong alkali | Not quartz — choose another material. |
Quartz tube vs borosilicate vs alumina tube
| Property | Fused quartz tube | Borosilicate 3.3 tube | 99.7% alumina tube |
|---|---|---|---|
| Continuous use | ≈ 1200°C | ≈ 500°C | ≈ 1600°C or higher |
| Thermal expansion | ≈ 5.5 × 10⁻⁷ /°C | ≈ 3.3 × 10⁻⁶ /°C | ≈ 8 × 10⁻⁶ /°C |
| Thermal shock | Excellent | Moderate | Limited; heat slowly |
| Transparency | Transparent from UV to near IR (grade dependent) | Transparent in the visible; cuts off the deep UV | Opaque |
| Composition | SiO₂ ≥ 99.99% | SiO₂ with B₂O₃, Na₂O, Al₂O₃ | ≈ 99.7% Al₂O₃ plus sintering additives |
| Main limits | HF, hot phosphoric acid, hot alkali | Low maximum temperature; HF and hot alkali | No visual access; thermal-shock risk |
Typical handbook values for comparison. Exact figures depend on grade and supplier. More detail: quartz glass vs borosilicate glass.
Custom quartz glass tubes
Customization
Straight drawn stock is only the starting geometry. FGQuartz cuts, machines, flame-forms, and welds tubes into process-ready assemblies — from a single prototype to production, with no minimum order quantity. Process detail: thermal (flame) processing and cold (CNC and grinding) processing; non-tube parts are on the custom quartz glass page.
| Capability | Detail |
|---|---|
| Diameter | OD from 5 mm to 1000 mm, including large-diameter process sizes. |
| Length | Cuts to length up to 3000 mm; longer runs via welded sections. |
| Wall thickness | Thin-wall through heavy-wall (0.5–20 mm+), including vacuum-duty walls. |
| Dimensional tolerance | Drawn tolerance or tighter OD control via centerless grinding, per drawing. |
| End configuration | Plain, chamfered, fire-polished, flanged, threaded, or sealed (domed / flat). |
| Holes and ports | Diamond core-drilled gas, sensor, and exhaust ports. |
| Slots and steps | CNC milling of locating grooves, steps, and mating interfaces. |
| Flanges | Fused or machined flanges for equipment sealing. |
| Bends | Oxy-hydrogen flame-formed bends at specified radius and angle. |
| Special geometry | Necking, expansion, tapers, nozzles, and multi-section welded structures. |
| Surface finishing | Fire polishing, grinding, and annealing after hot or cold work. |
Flame-formed fused silica U-bends — precision bent and annealed in the same facility as the drawn tube for process and laboratory lines.
Closed-end fused silica tube — one end sealed by flame working, cut and annealed in the same facility as the drawn tube for process and laboratory use.
Custom fused silica labware with ground joints — bottles, vessels, and closed tubes fabricated and annealed in-house for laboratory and pilot use.
Tube types we fabricate
| Tube type | Typical use | What is fabricated |
|---|---|---|
| Standard tubes | Diffusion furnaces, fiber preform sleeves, furnace cylinders | Continuous-drawn, controlled OD/ID and concentricity. Clear or opaque. Thin-wall or heavy-wall. |
| Flanged tubes | Process chambers, vacuum / UHV interfaces | Thermally fused or CNC-machined flanges with O-ring sealing faces. |
| Threaded tubes | Modular ultra-pure assemblies in the hot zone | CNC-milled external or internal threads. Custom thread forms to drawing. |
| Ports and manifolds | Gas injection and sensing on LPCVD / CVD tools | Side-arm tubes, multi-port manifolds, thermocouple sheaths. |
| Bent tubes | Compact layouts and non-straight gas or heat paths | Flame-formed U, L, and custom radii with wall integrity held through the bend. |
| Welded assemblies | Integrated reactor-style structures | Tube-to-tube and tube-to-plate joints, post-weld annealing, leak-tight multi-part geometry. |
Representative tube builds
Project examples
Four typical custom tube projects, described by the requirement, the build route, and what is checked against the drawing. Customer names and confidential drawing data are withheld.
01 · Semiconductor
Flanged LPCVD process tube
Requirement. Large-OD process tube with an O-ring sealing flange, plus side ports for gas injection and a thermocouple.
How it is built. Drawn tube cut to length, ports core-drilled, flange fused on or CNC-machined with an O-ring face, then stress-relief annealed.
Checked against the drawing. OD, ID, wall thickness, concentricity, and flange-face geometry.
02 · Fiber optic
Preform substrate and jacketing tube
Requirement. Tube with tight concentricity and uniform wall for MCVD substrate use, or for jacketing and overcladding of preforms.
How it is built. Fused quartz or synthetic fused silica selected to the process, OD brought to tolerance by centerless grinding where the drawn tolerance is not enough, ends cut and fire-polished.
Checked against the drawing. OD, ID, wall uniformity, and bow / concentricity (a class below 0.1 mm/m where specified).
03 · Laboratory and pilot
U-shaped process line
Requirement. Compact, non-straight gas or heat path inside a laboratory or pilot furnace.
How it is built. Flame-formed U bend at the specified radius with wall integrity held through the bend, annealed after the hot work.
Checked against the drawing. Bend radius, leg length, OD, and end configuration.
04 · Furnace equipment
Extended-length welded tube
Requirement. A furnace chamber tube longer than the 3000 mm standard run.
How it is built. Matched tube sections joined by oxy-hydrogen flame welding, then post-weld annealed and fire-polished at the ends.
Checked against the drawing. Straightness across the joints, overall length, and end features.
Drawn, machined, and flame-worked under one ISO 9001 system
Manufacturing and quality
FGQuartz operates a 15,000 m² facility in Lianyungang covering melting, CNC diamond machining, oxy-hydrogen flame forming, welding, fire polishing, and annealing, so industrial tube specifications are executed in-house rather than outsourced. Learn more about FGQuartz.
Handling: clean with an acid bath or alcohol wipe before high-temperature use. Alkali salts and fingerprints catalyze devitrification above roughly 1150°C. Support large-diameter or thin-wall tubes along their length.
Quartz glass tube applications
Applications
Why specify FGQuartz
Manufacturer
Procurement questions
FAQ
Yes, up to 1000 mm class outer diameter for large process equipment. See our dedicated large-diameter quartz tubes page for more detail.
Quartz tubes support continuous operation up to 1200°C and short-term exposure to 1300°C, with a softening point of approximately 1680°C.
Pricing depends on diameter, wall thickness, end features (flange, thread, ports), and tolerance requirements. A plain cut length is far less expensive than a flanged, threaded, or welded multi-port assembly.
Yes. FGQuartz flame-forms bends with controlled radius and wall integrity, and welds multi-part tube assemblies into leak-tight, complex geometries such as reactor vessels and multi-port manifolds.
A flanged tube has a fused or machined flange face designed for O-ring sealing against equipment, typically used in vacuum or UHV systems. A threaded tube has CNC-milled threads for metal-free mechanical fastening, often used in modular assemblies.
FGQuartz supplies quartz tubes from 5 mm to large-diameter process sizes up to 1000 mm class, with wall thickness from 0.5 mm to 20 mm+ and standard lengths up to 3000 mm, extendable via welded sections.
Quartz glass tubes carry gases, house wafers, contain reactions, or route heat through extreme-temperature process equipment in semiconductor, solar, fiber optic, and laboratory applications, without introducing contamination.