ASTM F975-86(1993)E01

Specification for Auxiliary Single Stage Steam Turbines for Shipboard Use (Withdrawn 2000)

SCOPE
1.1 This specification covers minimum requirements for shipboard auxiliary single-stage steam turbines.  
1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.  
1.3 The following precautionary caveat pertains only to the test method portion, Section 11, of this specification: This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Withdrawn
• Publication Date: 31-Dec-1992
• Withdrawal Date: 09-May-2000
• Technical Committee: F25 - Ships and Marine Technology
• Drafting Committee: F25.11 - Machinery and Piping Systems

Standards Content (Sample)

e1
Designation: F 975 – 86 (Reapproved 1993) An American National Standard
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Specification for
Auxiliary Single Stage Steam Turbines for Shipboard Use
This standard is issued under the fixed designation F 975; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Section 15 was added editorially in May 1993.
1. Scope SM 23 Steam Turbines for Mechanical Drive Service
1.1 This specification covers minimum requirements for
3. Terminology
shipboard auxiliary single-stage steam turbines.
3.1 Unless otherwise specified herein, terms and expres-
1.2 The values stated in inch-pound units are to be regarded
sions shall be in accordance with the definitions contained in
as the standard. The values given in parentheses are for
the following documents, in order of precedence as follows:
information only.
3.1.1 NEMA SM 23, Section 2, General; Section 4, Gov-
1.3 The following precautionary caveat pertains only to the
erning Systems; and Section 5, Overspeed Trip Systems.
test method portion, Section 11, of this specification: This
3.1.2 Mechanical Engineers Handbook
standard does not purport to address all of the safety problems,
3.1.3 Webster’s New International Unabridged Dictionary.
if any, associated with its use. It is the responsibility of the user
3.2 Definitions of Terms Specific to This Standard:
of this standard to establish appropriate safety and health
3.2.1 constant speed governor—a governor which, by its
practices and determine the applicability of regulatory limita-
control of the steam to the turbine, automatically maintains the
tions prior to use.
speed of the turbine at a predetermined rate, under all specified
conditions of load, exhaust, and pressure.
2. Referenced Documents
3.2.2 single-stage turbine—a steam turbine that has one
2.1 ASTM Standards:
velocity-compounded stage or pressure stage.
A 367 Test Methods of Chill Testing of Cast Iron
3.2.3 speed limiting governor—a governor which, by con-
2.2 Federal Standard:
trol of the steam to the turbines, will not permit the turbine to
H 28/21A Metric Screw Threads
operate at a speed in excess of that to which the governor is
2.3 ANSI Standards:
adjusted but will permit the turbine to continue in operation at
ANSI/AFBMA 9 Load Ratings and Fatigue Life for Ball
this speed.
Bearings
4. Ordering Information
B1.1 Unified Inch Screw Threads (UN and UNR Thread
Form) 4.1 Ordering information to be included is shown in Annex
A2.
B16.5 Pipe Flanges and Flanged Fittings, Steel Nickel Alloy
and Other Special Alloys
5. Materials
2.4 ABS Document:
5 5.1 Materials of construction shall have a minimum impact
Rules for Building and Classing Steel Vessels
strength in accordance with ASME Section VIII, Division 1,
2.5 ASME Document:
Table UG-84. Materials not listed shall be approved by ABS.
Pressure Vessel Code, Section VIII, Pressure Vessels,
6 5.2 Unless otherwise approved, forgings, rolled plate, and
Division I
castings shall be of the following materials:
2.6 NEMA Document:
5.2.1 Carbon Steel, where the temperature will not exceed
775°F (413°C).
This specification is under the jurisdiction of ASTM Committee F-25 on 5.2.2 Carbon-molybdenum Steel, where the temperature is
Shipbuilding and is the direct responsibility of Subcommittee F25.11 on Machinery.
between 775°F (413°C) and 875°F (468°C).
Current edition approved Feb. 28, 1986. Published August 1986.
5.2.3 Chromium-molybdenum Steel, where the temperature
Annual Book of ASTM Standards, Vol 01.02.
is between 875°F (468°C) and 1050°F (565°C).
Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700
Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
5.2.4 The use of grey cast iron is not permitted. Ductile cast
Available from American National Standards Institute, 11 W. 42nd St., 13th
nodular iron may be used in accordance with ASME Section
Floor, New York, NY 10036.
VIII.
Available from American Bureau of Shipping, 45 Eisenhower Dr., Paramus, NJ
07652.
Available from American Society of Mechanical Engineers, 345 E. 47th St.,
New York, NY 10017. Available from NEMA, Suite 300, 2101 L St. N.W., Washington, DC 20037.
F 975
5.3 Castings shall be sound and free of shrink holes, blow accordance with good marine engineering practice.
holes, scale blisters, or other similar defects. Surfaces shall be 7.2 Accessibility and Maintenance:
thoroughly cleaned by sandblasting, shotblasting, pickling, or 7.2.1 All parts requiring routine examination, maintenance,
other standard methods. or replacement shall be readily accessible. Minimum effort
5.4 Nozzle rings or blocks shall be of corrosion-resistant shall be required to accomplish planned maintenance and to
steel containing 11 to 13 % chromium. affect repairs.
5.5 Blading shall be of corrosion-resistant steel containing 7.2.2 Turbines shall be maintainable in accordance with the
11 to 13 % chromium and heat treated to produce necessary procedures in Annex A1.
physical properties. Shrouding shall be of the same material or 7.3 Installation Requirements:
material having similar chemical properties as the blade. 7.3.1 Envelope design shall provide for satisfactory opera-
Impulse blades shall normally be machined from bar stock or tion when turbine is installed onboard ship as specified and
stock of cross-section approximately the blade shape. when subjected to the following trim, list, roll, and pitch
5.6 Fastener materials shall be selected with regard to conditions:
operating environment. Materials compatible with mating sur- 7.3.1.1 Five degrees permanent trim, forward or aft.
faces, design operating temperatures, and loading must be 7.3.1.2 Fifteen degrees permanent list, port or starboard.
used. 7.3.1.3 Forty-five degrees full period (22.5 degrees half
5.7 Governor fulcrum points, valve stems, springs, adjust- amplitude) roll.
ing screws, or similar elements or surfaces where sliding or 7.3.1.4 Fifteen degrees pitch (bow up to bow down) full
rotary motion is experienced shall be of corrosion resistant period (7.5 degrees half amplitude). Period of motion if
materials. required, shall be as specified in the ordering data. Athwart-
ships and fore and aft inclinations occur simultaneously.
6. Performance Requirements
7.4 Environmental Operating Conditions:
6.1 Steam Conditions, maximum and minimum pressure
7.4.1 External Vibrations—When specified in the ordering
and temperature under which the turbine is to meet power data, the turbine shall withstand the following ship-board
requirements shall be specified in the ordering data.
vibrations without malfunction or requirement for additional
6.2 Available Steam Flow Conditions, in accordance with maintenance beyond that specified in Annex A1.
6.1 to meet power requirements shall be specified in the
Frequency Single Amplitude Displacement, 6
(Hz) in. (mm)
ordering data.
6.3 Vibration:
4 to 15 0.030 6 0.006 (0.762 6 0.152)
6.3.1 Turbine rotors shall be dynamically balanced to a
16 to 25 0.020 6 0.004 (0.508 6 0.102)
26 to 33 0.010 6 0.002 (0.254 6 0.051)
value of unbalance no greater than that which will yield a
maximum double amplitude vibration of 2.0 mils (0.050 mm),
7.4.2 Ambient Temperatures—Turbines shall be suitable for
up to 4000 rpm and 1.5 mils (0.038 mm) above 4000 rpm as
operations in 122°F (50°C) maximum ambient temperature
measured on the shaft adjacent to a bearing during turbine run
unless otherwise specified in the ordering data. Minimum
test.
ambient conditions must be specified in the ordering data.
6.3.2 Horizontal turbines shall have an exposed length of
7.5 Noise—When specified in the ordering data, sound
rotor shaft adjacent to a bearing to allow measurement of shaft
pressure levels shall be in accordance with NEMA SM 23,
displacement. The exposed portion of the shaft shall be
Section 7, Sound Pressure Levels.
machined to a surface finish of 32 μin. (0.8 μm) rms maximum.
8. Minimum Basic Design Requirements
For vertical turbines where the vibration cannot be measured
8.1 Critical Speed—Turbines shall have the first critical
on the shaft, the double amplitude of vibration as measured on
speed at not less than 25 % above the maximum operating
the bearing housing shall not exceed 50 % of the shaft limit
speed or not less than 10 % above overspeed trip setting,
specified in 6.3.1.
whichever is greater.
6.3.3 When specified in the ordering data, the turbine
8.2 Rotors:
manufacturer shall provide a boss on a bearing cap for the
8.2.1 Materials for rotors shall be as specified in Section 5.
purpose of accommodating installation of transducers for
8.2.2 Solid rotors shall be machined from a single forging.
vibration measurement.
For built-up rotors, wheel(s) shall be shrunk and keyed to the
6.4 Performance Curves—When specified in the ordering
data, the turbine vendor shall provide performance curves. shaft.
8.2.3 Turbine shafts having carbon ring packing shall be
7. General Design Requirements
coated with suitable protective material in the gland sealing
7.1 Design Life—Turbines shall operate satisfactorily over areas. Shafts shall have a surface finish of 32 μin. (0.8 μm) rms
the specified life of the ship when operated under specified
maximum in the area where seals contact the shaft.
design conditions and maintained in accordance with good 8.2.4 Minimum diameter of turbine rotor shafts, factors of
marine engineering practice including maintenance measures safety, elastic stresses, mean tangential stress, and blade design
outlined in 7.2.2. Ship life is to be specified in the ordering are to be determined by ABS Rules for Building and Classing
data. Those parts not classified as spare parts shall not require Steel Vessels.
replacement or repair during the design life under conditions of 8.3 Bearings:
operation specified in the ordering data when maintained in 8.3.1 Bearings and housings shall be match-marked or
F 975
designed to ensure proper assembly and position. the actual spring operating temperature.
8.3.2 Deflectors or other means shall be provided to prevent 8.6.5 Carbon Packing Limitations:
leakage of lubricant into the gland system or leakage of 8.6.5.1 Carbon packing shall be limited to a maximum
condensate into the bearings.
pressure differential of 25 psi (1.7 bar g) per ring.
8.3.3 Thrust bearings shall take thrust in both axial direc-
8.6.5.2 Carbon packing shall not be used where exhaust
tions. temperatures exceed 750°F (400°C).
8.3.4 Where rolling contact bearings are used they shall be 8.6.5.3 For carbon packing seal installation, shaft surface
in accordance with ANSI/AFBMA Standard 9 for either grease speeds shall not exceed 160 ft/s (48.8 m/s).
or oil lubricated application.
8.6.6 Metallic Labyrinth Packing:
8.3.5 Journal bearings shall be lined with babbit metal
8.6.6.1 Labyrinth packing projections shall be integral with
firmly secured in the bearing shells.
the packing ring and of softer material than the rotating sealing
8.3.5.1 Bearing pressure shall not exceed 250 psi (1.724 surface to minimize scoring if contact occurs.
MPa) of projected area based on static loading.
8.6.6.2 Packing shall be spring-loaded segments of a full
8.3.5.2 Bearing oil discharge temperature shall not exceed circle, and metal to metal contacting steam sealing surfaces
180°F (82.2°C). Temperature rise shall not exceed 50°F shall be finished to not more than 63 μin. (1.6 μm) rms.
(10°C).
8.7 Bolting:
8.4 Casing and Steam Chest:
8.7.1 Threads on all fasteners shall be in accordance with
8.4.1 Casing and steam chest materials shall be as specified one of the following standards: ANSI B1.1 and Federal
in Section 5.
Standard H 28/21A.
8.4.2 Casing and steam chests may be cast, fabricated, or 8.7.2 Through bolts shall be used wherever possible. The
combinations of both, and shall be sufficiently rugged to number of tapped holes in pressure parts shall be minimized.
withstand without fracture or distortion normal strains (that is, Where tapped holes are necessary, studs should be used in lieu
temperature, loads, or piping stresses) to which they will be of cap screws, the latter being used only where space precludes
subjected. clearing a part over the studs.
8.4.2.1 Sizing of steam connections shall be such that with 8.7.3 Fasteners installed in the interior of the turbine case
full load and normal steam conditions, inlet velocity shall not shall be secured to prevent loosening and shall be retained by
exceed 150 ft/s (45.7 m/s) and exhaust velocity shall not a method of locking in the event of fastener failure.
exceed 250 ft/s (76.2 m/s) for noncondensing and 450 ft/s (137 8.8 Auxiliary Piping:
m/s) for condensing applications.
8.8.1 Threaded connections for flammable fluids and steam
8.4.2.2 Casing and steam chest joints shall be metal to above 75 psig (5.2 bar g) shall be seal welded.
metal; however, sealant materials may be used as specified in
8.8.2 Pipe threads and tapped openings shall conform to
8.9.
ANSI B1.1 and B16.5, respectively.
8.4.2.3 Provisions shall be made for thorough drainage of
8.8.3 Threaded connections shall not exceed 1.5 in. nominal
all parts of turbine casing and steam chest. Impulse turbines
size.
shall be such that water cannot accumulate to the point where
8.8.4 Flanges and fittings shall conform to ANSI B16,
shrouds touch the water.
B16.4, and B16.5 as applicable for allowable stresses, flange
8.4.2.4 On horizontally mounted units inlet steam piping
ratings, and geometry.
need not be removed to lift the upper half case.
8.8.5 Welded lube oil pipe assemblies shall be cleaned of
8.4.2.5 Hand nozzle valves (except seats) shall be renew- scale by pickling in acid solution, flushing, neutralizing,
able without turbine case disassembly.
reflushing, and drying and preserving pending installation.
8.4.2.6 Nozzle and reversing chambers shall be mechani-
8.8.6 Prior to final drying and preservation, welded pipe
cally retained. assemblies shall be hydrostatically tested in accordance with
8.5 Steam Strainers—A corrosion resistant steel strainer 11.2.
element will be provided upstream of the turbine governing 8.8.7 Seal welds may be used on permanently assembled
valve, trip valve, or trip and throttle valve. threaded joints. Welded threaded joints shall have clean dry
threads and no thread compound used during makeup of the
8.6 Shaft Sealing—Casing shaft seals shall be designed to
minimize or prevent loss of steam from the turbine casing and joint. Fillet welds shall be made with not less than two passes
and shall completely cover the threads.
additionally, in condensin
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