Rating
| Concentration | 20 °C | 50 °C | Remark |
|---|---|---|---|
| 1 % | A | A | |
| 30 % | A | C | |
| 45 % | A | C | |
| 50 % | A | C | |
| 60 % | A | C | |
| concentrated | B* | – |
* estimated rating, given in the source without a temperature
Material comparison at 20 °C
Resistance overview
The resistance of SS 316 to Sodium Hydroxide (Caustic Soda) is concentration-dependent. Across the 6 tested concentrations (1 %, 30 %, 45 %, 50 %, 60 %, concentrated), the 20 °C rating ranges from A at lower concentrations to C at higher ones. This means engineers must verify which concentration their process actually involves before relying on a single rating. However, at 50 °C the resistance rating drops, indicating that temperature must be factored into the design. For heated applications, additional testing under actual service conditions is strongly recommended.
Application context
Sodium Hydroxide (Caustic Soda) is commonly encountered in textile processing and pulp and paper. SS 316 (Stainless steel 1.4401 (AISI 316)) is a metal typically used for vessels, heat exchangers, fittings and structural components. Because Sodium Hydroxide (Caustic Soda) is classified as corrosive, the choice of containment material is especially critical to prevent leaks, equipment damage, and safety hazards.
Practical recommendation
SS 316 can be used with confidence for Sodium Hydroxide (Caustic Soda) containment and handling. The A rating indicates that the material shows no significant change in weight, dimensions, or mechanical properties after prolonged contact under test conditions. At elevated temperatures (50 °C), some reduction in resistance occurs, so periodic inspection is advisable for heated applications. Always verify performance under actual operating conditions before committing to a design.
Did you know?
When choosing between metals for Sodium Hydroxide (Caustic Soda) service, engineers consider not just the resistance rating but also factors such as permeation rate, creep resistance, and weldability.
Materials rated A or B at 20 °C
Based on the row for 60 %, 20 °C.
- Thermoplastics
- HDPE A, PP A, LDPE A, Nylon (PA) A, Polystyrene A, Polysulfone A, PMP A
- Fluoropolymers
- PTFE A
- Elastomers
- EPDM A, NBR B
- Metals
- SS 304 A
About SS 316
Stainless steel 316 (1.4401) contains molybdenum, which improves resistance to chlorides over 304. Hydrochloric acid and other halide acids still cause pitting.
Rating scale
- A very good resistance
- B good resistance
- C limited resistance
- D not resistant
- – no data
- K no general statement possible
A rating marked * is an estimate in the source, not a test result. An estimate is given as one value without a temperature.
About this data
The ratings come from the chemical resistance list published by Bürkle GmbH, which compiled them from raw-material manufacturers’ data. They describe laboratory tests on the raw material at 20 °C and 50 °C.
A finished part also sees pressure, mechanical stress, welds and mixtures that a laboratory test does not. Treat the rating as a first filter and test under your own conditions before relying on it.