There is no definitive answer to this question as the maximum working pressure for a nut splitter will vary depending on the specific model and design of the tool. However, it is generally accepted that most nut splitters can safely handle pressures up to around 10,000 psi. Therefore, if you are planning to use a nut splitter for a project that requires higher levels of pressure, it is always best to consult with the manufacturer or an experienced professional beforehand to ensure that the tool can safely handle the desired pressure.