This standard covers the minimum requirements for general-purpose steam turbines for refinery service. These requirements include basic design, materials, related lubrication systems, controls, auxiliary equipment, and accessories. Note: A bullet (--) at the beginning of a paragraph indicates that either a decision is required or further information is to be provided by the purchaser. This information should be indicated on the data sheets (see Appendix A): otherwise, it should be slated in the quotation request or in the order. -- Steam turbines are classified as general- or special-purpose according to service requirements. The purchaser will specify the type of turbine that is best suited to his needs. General-purpose turbines are horizontal or vertical turbines used to drive equipment that is usually spared, is relatively small in size (power), or is in noncritical service. They are generally used where steam conditions will not exceed a pressure of 700 pounds per square inch gauge (48 bar gauge) and a temperature of 750 °C (400 °C) or where speed will not exceed 6000 revolutions per minute. Special-purpose turbines are horizontal turbines used to drive equipment that is usually not spared, is relatively large in size (power), or is in critical service. The use of special-purpose turbines is not limited by steam conditions or turbine speed. Requirements for special-purpose turbines are defined in API Standard 612.