API STD 612 pdf download.Petroleum, petrochemical and natural gas industries — Steam turbines — Special-purpose applications
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply. (See Annex B for a guide to steam turbine nomenclature.) 3.1 alarm point preset value of a measured parameter at which an alarm is actuated to warn of a condition that requires corrective action 3.2 anchor bolts bolts used to attach the mounting plate to the support structure or foundation 3.3 axially split split with the principal joint parallel to the shaft centreline 3.4 control mechanism all of the equipment between the speed governor and the governor-controlled valve(s) (such as linkages, pilot valves, power servos, and so forth) 3.5 critical speed shaft rotational speed at which the rotor-bearing-support system is in a state of resonance 3.6 design equipment manufacturer’s description of various parameters relevant to the equipment NOTE This terminology is for use only by the equipment manufacturer and is not intended to appear in the purchaser’s specifications. 3.7 fail safe system system which causes the equipment to revert to a permanently safe condition (shutdown and/or depressurized) in the event of a component failure or failure of the energy supply to the system 3.8 field changeable design feature that permits alteration of a function after the equipment has been installed NOTE The alteration can be accomplished by the following: a) soldering jumper leads to terminal pins especially provided for this purpose; b) employing circuit-board-mounted switches or potentiometers; c) using a shorting or diode-pin-type matrix board; d) using prewired shorting plugs; e) using authorized controlled access. 3.9 gauge board bracket or plate used to support and display gauges, switches, and other instruments NOTE A gauge board is open and not enclosed.3.10 general-purpose turbines horizontal or vertical turbines used to drive equipment that is usually spared, is relatively small in size (power), or is in non-critical service NOTE General-purpose steam turbines are intended for applications where the inlet gauge pressure does not exceed 4 800 kPa (48 bar) (700 psi) and the inlet temperature does not exceed 400 °C (750 °F), and where the speed does not exceed 6 000 r/min. 3.11 governor-controlled valve device that controls the flow of steam into or out of the turbine in response to the speed governor 3.12 hold-down bolts mounting bolts bolts that hold the equipment to the mounting plate or plates 3.13 hydrodynamic bearings bearings that use the principles of hydrodynamic lubrication NOTE The bearing surfaces are oriented so that relative motion forms an oil wedge, or wedges, to support the load without shaft-to-bearing contact. 3.14 local 〈device〉 mounted on or near the equipment or console 3.15 maximum allowable speed highest speed at which the manufacturer’s design permits continuous operation 3.16 maximum allowable temperature maximum continuous temperature for which the manufacturer has designed the equipment (or any part to which the term is referred) when handling the specified fluid at any specified operating conditions 3.17 maximum allowable working pressure maximum continuous pressure for which the manufacturer has designed the equipment (or any part to which the term is referred) when handling the specified fluid at the maximum allowable temperature 3.18 maximum continuous speed highest speed at which the turbine, as built and tested, is capable of continuous operation, at any of the specified steam conditions3.21 maximum inlet pressure and temperature highest inlet steam pressure and temperature conditions at which the turbine is required to operate continuously 3.22 maximum sealing pressure highest pressure the seals are required to seal during any specified static or operating conditions and during startup and shutdown 3.23 minimum allowable speed lowest speed at which the manufacturer’s design permits continuous operation 3.24 minimum exhaust pressure lowest exhaust steam pressure at which the turbine is required to operate continuously 3.25 minimum inlet pressure and temperature lowest inlet steam pressure and temperature conditions at which the turbine is required to operate continuously 3.26 normal operating point point at which usual operation is expected and optimum efficiency is desired NOTE This point is usually the point at which the vendor certifies that performance is within the tolerances stated in this International Standard.