Materials / Corrosion tables

Borosilicate glass 3.3, glass lined steel, stainless steel 316 / 316L others, different alloys are better known by their brand names such as Schott, Pyrex, Hastelloy, ..

Büchi Glas Uster – R&D and process equipment in corrosion resistant material

Büchi reactors systems are available in different materials: Depending on involved chemistry and requested process temperatures and process pressures we supply chemical process equipment in materials like: Borosilicate glass 3.3glass lined steel , with reduced resistance against acids but for higher pressure applications in stainless seel 316/316L, Hastelloy C22, (see also Inconel, Monel), Titanium of different grades, Tantalum , Nickel, Zirconium, Silicon Carbide (SiC), Teflon or PTFE (coatings, inliners). Combinations of these materials in the same system are made, where useful, as well as coating with different acid resistant materials as PFA.

Chemical reactors for pressure applications are often made in Borosilikat Glass 3.3 and glass lined steel for limited pressures, for higher pressure in stainless steel, different alloys like Hastelloy, Inconel or Monel, Titanium, Nickel, Tantalum, Zirconium.

Chemical reactors for vacuum application applications are typically made of Borosilicate Glass 3.3 and glass lined steel, sometimes in combination with glass distillation overheads in stainless steel, or Hastelloy.

Process equipment for vacuum distillation in production scale are built with glass lined reactors and a glass distillation overheads. All components like distillation column and piping are made in glass, feed vessels and receiving vessels in glass or glass lined steel, the condensers in glass, sometimes in combination with silicon carbide (SiC).

Borosilicate glass 3.3, acc. ISO 3585 consists of the following components:
81 % SiO2
13 % B2O3
4 % Na2/K2O
2 % Al2O3

Borosilicate glass was developed in 1887 by Otto Schott and Ernest Abbe in Jena Germany.

Chemical properties:
Very good chemical resistance against many substances. (according ISO 719, DIN 12116, ISO 695)


  • hydrofluoric acid
  • strong phosphoric acid
  • strong sodium hydroxide

Brandnames of Borosilicate 3.3 are: Duran, Pyrex, Jena Glass

Physical properties:
Density p    2,23
thermal expansion coefficient    3.3 * 10-6/K
(linear between 20 - 300°C)
medium specific heat capacity  0.84 J/gK
medium heat conductivity  1.30 W/mK

Optical properties
suitable for photochemical processes, specifically in the ultraviolet range 280 – 400 nm
(light transmission 310 – 2200 nm, visible light 380-780  nm)

Borosilicate glass 3.3 is used in chemical reactors and process equipment due to several reasons:

  • wide temperature range (often limited by the sealing material)
  • very low thermal expansion (linear over a wide temperature range)
  • it’s hydrophobic characteristic makes it easy to clean the complete chemical or pharmaceutical reaction unit
  • the inert attitude
  • it is transparent - processes can be observed and controlled visually

The chemical resistance against water , many chemical substances and pharmaceutical products (hydrolytic class 1) is explained by the high content of Bor. Reaction vessels made of Borosilicate glass suit perfectly to the requirements for use in chemical research labs, as well as Pilot Plants and kilolabs for small to mid scale productions in the pharmaceutical industry.

Safety with glass equipment:
Design is according to AD 2000 Merkblatt and PED (Pressure equipment directive) for use of our glass equipment and vacuum as well for glass reactors under pressure. Tightness, safety, reliability as well as short down times for cleaning and product changes are of major importance. Our reaction systems provide operator safety and safe processes due to several factors as the consequent use of flexible glass connections. Our unique glass connection stays flexible under operation condition and therefore free from mechanical forces. It can even compensate material expansions from other materials connected with more important expansion characteristics during heating and cooling, without the use of unsafe and hardly cleanable compensators.

Glass lined steel or enamelled steel reactors with glass column / glass cover:
Buchi reactors are built in a combination of the bottom part in glass lined steel with heating/cooling jacket in the bottom and a glass cylinder or glass cover on the top to visually observe the chemical reaction. Both materials of construction are inert and corrosion resistant and the glass lined steel Bottom heating features an excellent thermal transfer.

Buchi Reactors for Pilot Plants and kilo labs
These reactor systems in reactor volumes of 15 – 250 liters are mostly used for as multipurpose units. Due to this it is important to use chemically inert materials like glass, glass lines steel, PTFE or Teflon. There are reasons to combine glass distillation overheads also with reactors in different materials: For better heat transfer (with less corrosion resistance), the reactor may be built in Hastelloy, or in stainless steel in case of processing caustic solutions with less corrosion resistance on the acidic side. Other reasons of using Hastelloy or stainless steel reactors instead of our standard glass lined steel / glass reactors may be the operation on higher pressures, followed by vacuum distillation after the pressure reaction.