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Specialised glass formulations, matched to the process.
STAHL GLAS offers different glass formulations tailored to specific process requirements. Each type is developed to enhance performance under its own application conditions — temperature band, cleanliness, visibility and release behaviour.
Glass formulations
Five grades. One of them is right for your duty.
The lining is the equipment. Get the grade wrong and everything downstream of it — corrosion life, batch cleanliness, cycle time — is compromised from day one.
STAHL GLAS SG-C
−25 °C to 220 °C
Designed for standard chemical applications that demand exceptional corrosion resistance, long-term durability and reliable performance across a wide temperature range.
STAHL GLAS SG-CT
−25 °C to 260 °C
The SG-C chemistry envelope extended upward — suitable for high temperature service where a standard grade would be operating at its limit.
STAHL GLAS SG-P
Pharmaceutical grade
Glass designed for pharmaceutical production, completely free from heavy metal contamination. Its non-stick surface properties enable cleaner processing and more cost-effective production.
STAHL GLAS SG-W
High-gloss reflective
A high-gloss reflective surface that gives easy optical contrast in photochromic reactions inside the reactor, significantly improving process visibility during operation.
STAHL GLAS SG-R
−25 °C to 220 °C
Featuring a non-stick surface, it minimises residue build-up for cleaner processing and enhanced production efficiency. Suitable for continuous operation within its temperature range.
Not sure which?
Send us the duty
Give us the medium, concentration, pH, operating temperature and cycle, and we will recommend a grade.
Comparison
The five grades side by side.
| Grade | Service temperature | Primary characteristic | Typical application |
|---|---|---|---|
| STAHL GLAS SG-C | −25 to 220 °C | Exceptional corrosion resistance and long-term durability | Standard chemical reaction, storage and distillation duty |
| STAHL GLAS SG-CT | −25 to 260 °C | High temperature capability | Processes running above the standard grade’s ceiling |
| STAHL GLAS SG-P | Pharmaceutical duty | Completely free from heavy metal contamination; non-stick | API and pharmaceutical production, cGMP reactors and ANFDs |
| STAHL GLAS SG-W | Process-dependent | High-gloss reflective surface, optical contrast | Photochromic reactions where the operator must see the batch |
| STAHL GLAS SG-R | −25 to 220 °C | Non-stick surface, minimal residue build-up | Continuous operation and sticky products where fouling costs yield |
Temperature limits are for the glass grade in isolation. The permissible difference between product and jacket temperature is a separate constraint — see thermal shock limits.
Selection
How the grade actually gets chosen.
Four questions decide it. Answer them honestly and the grade follows almost automatically.
What is the medium?
Type of corrosive substance, its concentration and pH. Concentrated acids are generally less corrosive than dilute — phosphoric acid is the exception.
How hot does it run?
Peak product and jacket temperature. Corrosion rate for bases roughly doubles for every 10 °C rise, so headroom matters more than the average.
How clean must it be?
Pharmaceutical production calls for SG-P — free from heavy metal contamination. Sticky products that foul the wall call for the non-stick SG-R.
Do you need to see it?
Where photochromic change is the process indicator, SG-W’s high-gloss reflective surface gives the operator real optical contrast.
One absolute limit: hydrofluoric acid
HF destroys glass lining at all concentrations. Even fluoride at 20 ppm in an acid environment has a devastating effect on the glass surface, particularly in continuous reactions where it is repeatedly replenished. Reactants that may carry fluoride impurities — technical-grade phosphoric acid and its salts especially — must be analysed before use. See corrosion resistance.
Where the limits can be pushed
Corrosion can often be inhibited rather than avoided. A few hundred ppm of silica protects the lining in acid service in the liquid phase, and silicone oils do the same in vapour phase. With alkalis, a few hundred ppm of calcium, aluminium or zinc can reduce attack, especially in dilute solution. Talk to us before ruling glass lining out.
Physical properties
What the fired lining is, in numbers.
- Thickness
- 1 – 2.2 mm
- Specific weight
- 2.5 g/cm³
- Tensile strength
- 70 N/mm²
- Compressive strength
- 800 N/mm²
- Hardness (HV)
- 700 kg/mm²
- Thermal conductivity
- 1.2 W/m·K
- Specific heat
- 0.82 kJ/kg·K
- Electrical resistivity
- 1013 Ω/cm at ambient temperature
- Dielectric strength
- 20 – 30 kV/mm
- Modulus of elasticity
- 75,000 N/mm²
- Elongation
- 0.1 %
- Abrasion
- 3.5 mg/min
- Chipping tendency
- None arising under normal operating conditions
- Flexibility
- The lining follows the base metal through bending until the metal itself deforms permanently
Standards & tests
The lining is measured against published standards.
Glass lining is tested to recognised DIN EN ISO methods rather than to an in-house opinion of what “good” looks like.
DIN EN ISO 28706
Resistance to chemical corrosion — acids, neutral liquids and alkalis, as applicable to the application.
DIN EN ISO 28721-1
Quality requirements for glass lined apparatus, Part 1.
DIN EN ISO 28721-3
Thermal shock and impact resistance, Part 3.
DIN EN ISO 15695
Scratch and abrasion resistance of the fired surface.
Vessel geometry follows DIN 28136 types AE and CE. Every lining is spark tested for integrity before despatch — see quality & testing.
Grade recommendation
Send the chemistry. We will name the grade.
Medium, concentration, pH, operating and cleaning temperatures, and cycle pattern — that is all we need to recommend a glass grade and flag anything in the process that would shorten lining life.