API 612 Special Purpose Steam Turbines For Petroleum, Chemical, and Gas Industry Services

API 612

 Special Purpose Steam Turbines For Petroleum, Chemical, and Gas Industry Services (1995 edition)

1. Scope

This standard covers the minimum requirements for special purpose steam turbines for petroleum, chemical, and gas industry services. These requirements include basic design, materials, and related lube-oil systems, controls, and auxiliary equipment.

Steam turbines are classified general-purpose or special purpose according to service requirement.

General-purpose turbines are those 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 intended for applications where conditions will not exceed 48 bar gauge (700 pounds per square inch gauge) pressure or 400°C (750°F) inlet temperature, or both, and where speed will not exceed 6000 revolutions per minute. Requirements for general purpose turbines are defined in API Standard 611.

Special purpose turbines are those horizontal turbines used to drive equipment that is usually not spared, is relatively large in size (power), or is in critical service. This category is not limited by steam conditions or turbine speed.

The vendor may offer alternative designs. Equivalent metric dimensions, fasteners, and flanges may be substituted as mutually agreed upon by the purchaser and the vendor.

In case of conflicting requirements between this standard and the inquiry or order, the information included in the order shall govern.

2. Contents:

Section 1 – General
1.1 Scope
1.2 Alternative designs
1.3 Conflicting requirements
1.4 Definition of terms
1.5 Referenced publications
Section 2 – Basic design
2.1 General
2.2 Pressure casings
2.3 Casing appurtenances
2.4 Casing connections
2.5 External forces and moments
2.6 Rotating elements
2.7 Shaft seals
2.8 Dynamics
2.9 Bearings and bearing housings
2.10 Lubrication and control-oil system
2.11 Materials
2.12 Nameplates and rotation arrows
Section 3 – Accessories
3.1 Couplings and guards
3.2 Mounting plates
3.3 Gear units
3.4 Controls and instrumentation
3.5 Gland vacuum system
3.6 Piping and appurtenances
3.7 Insulation and jacketing
3.8 Special tools
3.9 Turning gear
Section 4 – Inspection, testing, and preparation for shipment
4.1 General
4.2 Inspection
4.3 Testing
4.4 Preparation for shipment
Section 5 – Vendor’s data
5.1 Proposals
5.2 Contract data
Appendix A – Typical data sheets
Appendix B – Gland sealing and leak-off system
Appendix C – Rotor dynamics logic diagrams
Appendix D – Procedure for determination of residual unbalance
Appendix E – Special-purpose steam turbine vendor drawing and data requirements
Figures
1 Rotor response plot
B-1 Typical gland sealing and leak-off system for condensing turbines
B-2 Typical gland leak-off system for back-pressure turbines
C-1 Rotor dynamics logic diagram (lateral analysis)
C-2 Rotor dynamics logic diagram (torsional analysis)
D-1 Sample plot and calculation of residual unbalance
Tables
1 Finish requirements for flange contact surfaces
2 Minimum piping schedules
3 Minimum tubing wall thickness
4 Minimum tubing wall thickness (instrument and control air)

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