Gear- units

API Std 613 Speeial-Purpose Gear Units for Refinery Serviees... 

API Std 613 Special Purpose Gear Units for Petroleum, Chemical, and Gas Industry Services, 4th Edition, June 1995... 

This standard covers the minimum requirements for general-purpose, enclosed single- and multi-stage gear units incorporating parallel-shaft... 

When selecting a high-speed gear unit, the possibility of using an AGMA No. 2 oil should be considered. In most cases, the sleeve bearings in the system can use this oil and, if not, a compromise 200 SSU at 100°F (38°C) oil should be considered. 

The larger the gear unit, the more important this eheek beeomes, sinee large housings tend to be more flexible. Also, the use of baseplates furnished by the original equipment manufaeturer does not eliminate faee eontaet problems, and these inspeetion proeedures should be earried out. 

API 613, Special Purpose Gear Units for Refinery Services, 2nd edition, Washington, D.C., 1977. 

The special purpose gear unit should have a specified API 613 service factor of 1.4 as a minimum. The service factor used in the gear design should be selected to meet the requirements of API for the application. 

The gear unit must be tuned to the system in which it operates. Die vendor with the train responsibility must analyze the system to be certain the gear unit will not transmit torsional or lateral vibrations to the rest o the system or be damaged by system excitations. 

If the gear unit is retrofit, for example when replacing a turbine with a motor and gear unit, the system, in like manner, must be thoroughly analyzed. In either case, the gear supplier must furnish the user with adequate data on the mass elastics of the unit, inertias, bearing characteristics, and the like, to permit the user s own or a consultant s analysis. 

An important consideration of a gear unit is the pitch line velocity (PLV), which is the product of the gear or pinion pitch diameter and the shaft speed of the gear or pinion. 

For maximum reliability, a gear-unit ratio must be within the capability of a single-step application. Practically, ratios may approach 6 1, but the preferred ratios are in the 3 1 to 5 1 range. 

A dry sump design should be employed. The gear unit for a train with a central lube oil system should be designed for the turbine grade oils of the system. Typically, 150 Saybolt Seconds Universal (SSU) oils at 100°F (ISO 32) with an inlet temperature of 110°F to 120°F are adequate. 

If the gear unit application must have its own oil supply, such as with some retrofits, the intent of the API 614 should be employed. 

Many of the compressors require some form of speed matching to the driver. For most drivers to reciprocating compressors, this will be a reducer. For gas turbines to almost all compressors, a gear unit is... 

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