This standard covers the minimum requirements for general-purpose@ enclosed single and multistage gear units incorporating parallel shaft helical and right angle spiral bevel gears for the petroleum@ chemical@ and gas industries. Gears manufactured according to this standard shall be limited to the following pitchline velocities. Helical gears shall not exceed 60 m/s (12@000 ft/ min)@ and spiral bevels shall not exceed 40 m/s (8@000 ft/min). Spiral bevel gearsets shall be considered matched sets. Note 1: This standard is not intended to apply to gears in special-purpose service@ which are covered in API Std 613; to gears integral with other equipment; to epicyclic gear assemblies; or gears with non-involute tooth forms. Note 2: This standard requires the purchaser to specify certain details and features. A bullet (?) at the beginning of a paragraph indicates that either a decision by@ or further information from@ the purchaser is required. Further information should be shown on the data sheets or stated in the quotation request and purchase order. General-purpose gears are applied in equipment trains that are usually spared@ or are in noncritical service. Typical applications for which this standard is intended are cooling tower water pump systems@ forced and induced draft fan systems@ and other general-purpose equipment trains.?