Pyrex 7740
ASTM E438 Type I · also Corning 7740
Pyrex 7740 (Corning 7740, E438 Type I) is the reference 3.3-expansion borosilicate silicate glass, combining low thermal expansion with good resistance to water, acids and saline solutions, and is supplied annealed, tempered or chemically strengthened.
Reference datasheet — Pyrex 7740 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the ANN condition
Pyrex 7740 tempers and conditions
Pyrex 7740 is supplied in 3 conditions, soft to hard. ANN is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefault Annealed | Default state for laboratory glassware, tubing, sight glasses and optics; can be cut, drilled and flame-worked. | 35 | 0 | 480 HV | 1 W/m·K | |
Thermally toughened (tempered) borosilicate | Pick for pressure sight glasses, oven doors, cooktop and safety panels where 3–5× bending strength and higher thermal shock capability are needed; cannot be cut or drilled after tempering. | 60 | 0 | 480 HV | 1 W/m·K | |
Chemically strengthened (ion-exchanged) borosilicate | Choose for thin (<3 mm) panes, windows and cover glass where optical flatness must be kept while raising surface strength; strength gain is smaller than in soda-lime glass because of the low alkali content. | 70 | 0 | 520 HV | 1 W/m·K |
What is Pyrex 7740?
Pyrex 7740 (Corning 7740, E438 Type I) is the reference 3.3-expansion borosilicate silicate glass, combining low thermal expansion with good resistance to water, acids and saline solutions, and is supplied annealed, tempered or chemically strengthened. It is used for labware, sight glasses, bakeware and chemical piping in tube, rod, plate and pressed forms. Design strength is modest at 35 MPa tensile, continuous service is limited to 230 °C, and machinability is low (score 12), with an annealing point of 560 °C and strain point of 510 °C. Fused quartz is the step up for higher temperature or UV duty. Pyrex 7740 has a density of 2.23 g/cm³ (0.0806 lb/in³), lighter than 85% of glass grades. Pyrex 7740 has a tensile strength of 35 MPa (5.08 ksi), weaker than 75% of glass grades. Elongation at break is 0% and the elastic modulus is 64 GPa (9.28 Msi).
What is Pyrex 7740 used for?
- Laboratory glassware
- Bakeware
- Sight glasses
- Chemical piping
Advantages
- Low embodied carbon — 1.7 kg CO₂/kg, better than 88% of glass grades
- Lightweight — 2.23 g/cm³ (0.0806 lb/in³), better than 85% of glass grades
- Good corrosion resistance — 92/100, better than 81% of glass grades
Limitations
- Limited service temperature — 230°C (446 °F), worse than 85% of glass grades
Pyrex 7740 properties
Typical room-temperature values for Pyrex 7740-ANN; bars are the position among glass grades.
Physical4
Pyrex 7740 has a density of 2.23 g/cm³ (0.0806 lb/in³), lighter than 85% of glass grades.
Mechanical12
Pyrex 7740 has a tensile strength of 35 MPa (5.08 ksi), weaker than 75% of glass grades. Elongation at break is 0% and the elastic modulus is 64 GPa (9.28 Msi).
Thermal5
Pyrex 7740 is rated for continuous service to 230°C (446 °F). It conducts heat at 1.1 W/m·K (0.659 BTU/hr·ft·°F), worse than 63% of glass grades. Thermal expansion is 3.3 µm/m·K (1.83 µin/in·°F).
Electrical5
Pyrex 7740 is an electrical insulator with a dielectric strength of 20 kV/mm (508 V/mil) and a resistivity of 1×10¹³ Ω·m.
Chemical & Environmental2
Corrosion resistance is excellent (92/100), better than 81% of glass grades.
Sustainability4
Producing a kilogram of Pyrex 7740 takes about 25 MJ of energy and emits 1.7 kg of CO₂ — less than 88% of glass grades. Typical recycled content is 10%.
Manufacturability2
Pyrex 7740's machinability is not recommended (12/100, worse than 68% of glass grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the glass family
Yield strength against density for every glass grade FabDigit runs. Pyrex 7740 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Pyrex 7740
Is Pyrex 7740 easy to machine?
Diamond core drilling, grinding, waterjet or CO₂/ultrafast laser only; always machine before tempering and re-anneal after heavy grinding.
Can Pyrex 7740 be welded?
Joined by flame or lathe glass-working at 800–1250 °C; seals matched to Kovar and to other 3.3 borosilicates, but not directly to soda-lime glass.
Can Pyrex 7740 be formed, bent or molded?
Formed by float, tube-drawing, pressing or blowing near the working point (~1250 °C); annealing point 560 °C, strain point 510 °C.
Pyrex 7740 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| B2O3≥8 % required for borosilicate 3.3 per ISO 3585 | 12 – 13.5 | 13 |
| Na2O | 3.5 – 4.5 | 4 |
| Al2O3 | 2 – 2.5 | 2.3 |
| K2Otrace, melt dependent | 0 – 0.6 | 0.1 |
| SiO2network former | ≥ 80 (balance) |
What surface finishes work on Pyrex 7740?
Fire polishing, optical polishing, acid etching (HF frosting), chemical strengthening or AR/ITO coating; edge seaming markedly raises usable strength.
Equivalent designations
Standards and trade names that resolve to Pyrex 7740 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- E438 Type I
- Trade names
- Corning 7740
How much does Pyrex 7740 cost?
Pyrex 7740 is a premium-cost glass ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Pyrex 7740 — frequently asked
What is Pyrex 7740 used for?
Pyrex 7740 is typically used for laboratory glassware, bakeware, sight glasses and chemical piping. In short: benchmark borosilicate 3.3; low-cost thermal-shock glass; kovar-matched sealing glass.
What is the tensile strength of Pyrex 7740?
Pyrex 7740 has a typical tensile strength of 35 MPa (5.08 ksi) — weaker than 75% of glass grades. Strength varies by condition: see the 3 listed tempers.
Is Pyrex 7740 easy to machine?
Not especially — machinability is rated not recommended (12/100, worse than 68% of glass grades). Diamond core drilling, grinding, waterjet or CO₂/ultrafast laser only; always machine before tempering and re-anneal after heavy grinding.
Can Pyrex 7740 be welded?
Joined by flame or lathe glass-working at 800–1250 °C; seals matched to Kovar and to other 3.3 borosilicates, but not directly to soda-lime glass.
What surface finishes work on Pyrex 7740?
Fire polishing, optical polishing, acid etching (HF frosting), chemical strengthening or AR/ITO coating; edge seaming markedly raises usable strength.
Can Pyrex 7740 be formed, bent or molded?
Formed by float, tube-drawing, pressing or blowing near the working point (~1250 °C); annealing point 560 °C, strain point 510 °C.
What is the maximum service temperature of Pyrex 7740?
Pyrex 7740 is rated for continuous use to about 230°C (446 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Pyrex 7740 cost?
Pyrex 7740 is a premium-cost glass ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM E438 — Standard Specification for Glasses in Laboratory Apparatus (Type I Class A) — ASTM International (2021)
- ISO 3585 — Borosilicate glass 3.3, properties — ISO (1998)
- Corning Code 7740 Pyrex glass properties sheet — Corning Incorporated (2014)
- BOROFLOAT 33 technical datasheet (mechanical, thermal, electrical, optical) — SCHOTT AG (2023)
- Engineered Materials Handbook Vol. 4: Ceramics and Glasses — ASM International (1991)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.