Spring load testing is quite interesting because a series of samples can be simultaneously tested, at various stress levels and directly in gaseous hydrogen environment, with a pass/fail result. Spring load thus can easily return statistical information on the behaviour of a certain material.
Test samples are sub-size tensile test samples with or without notch (effect of hydrogen stress-driven migration). After preliminary hydrogen charging, constant load is applied to the specimen by means of spring loading device (ASTM G49, NACE TM0177, ISO 16573‑1:2020) and exposed to gaseous hydrogen environment for 100 ÷ 200 h (ISO 16573). Maximum load 12 kN, T = RT ÷ 500 °C, p = 1 ÷ 200 bar.
Example of sample and spring load device with relative autoclave test chamber