ASTM F956-91(2023)

Standard Specification for Bell, Cast, Sound Signalling

ABSTRACT
This specification covers cast sound-signalling bells, together with bulkhead mounting plates for the smaller bells, for use on ships, boats, and other marine craft, for compliance with the rules in the convention on the International Regulations for Preventing Collisions at Sea. Bell bodies, clappers, and other cast fittings and parts shall be copper alloy. Fittings such as bolts, nuts, washers, pins, and supporting lugs shall be of copper alloy compatible with the bell castings. Bells shall have full, clear, round, and farreaching tones. The sound pressure level shall not be less than 110 dB at a distance of 1 m from it. Acoustic tests shall be conducted only for the 200 mm heavy and larger bells to check the requirements prescribed.
SCOPE
1.1 This specification covers cast sound-signalling bells, together with bulkhead mounting plates for the smaller bells, for use on ships, boats, and other marine craft, for compliance with the rules in the convention on the International Regulations for Preventing Collisions at Sea (commonly called Colregs).2 See Appendix X1.  
1.2 Bells and bulkhead mounting plate shall be sized as indicated in Section 4 (see Appendix X2).  
1.3 For consistency with International Regulations, all measurements are in SI units.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Apr-2023
• ICS: 47.020.70 - Navigation and control equipment
• Technical Committee: F25 - Ships and Marine Technology
• Drafting Committee: F25.07 - General Requirements

Relations

• Refers: ASTM B584-13 - Standard Specification for Copper Alloy Sand Castings for General Applications
• Effective Date: 01-Apr-2013
• Refers: ASTM B584-12a - Standard Specification for Copper Alloy Sand Castings for General Applications
• Effective Date: 15-May-2012
• Refers: ASTM B584-12 - Standard Specification for Copper Alloy Sand Castings for General Applications
• Effective Date: 01-May-2012
• Refers: ASTM B584-11 - Standard Specification for Copper Alloy Sand Castings for General Applications
• Effective Date: 01-Apr-2011
• Refers: ASTM B584-09a - Standard Specification for Copper Alloy Sand Castings for General Applications
• Effective Date: 15-Nov-2009
• Refers: ASTM B584-09 - Standard Specification for Copper Alloy Sand Castings for General Applications
• Effective Date: 01-Nov-2009
• Refers: ASTM B584-08 - Standard Specification for Copper Alloy Sand Castings for General Applications
• Effective Date: 01-Apr-2008
• Refers: ASTM B584-06a - Standard Specification for Copper Alloy Sand Castings for General Applications
• Effective Date: 01-Oct-2006
• Refers: ASTM B584-06 - Standard Specification for Copper Alloy Sand Castings for General Applications
• Effective Date: 01-Feb-2006
• Refers: ASTM B584-05 - Standard Specification for Copper Alloy Sand Castings for General Applications
• Effective Date: 01-Nov-2005
• Refers: ASTM B584-04 - Standard Specification for Copper Alloy Sand Castings for General Applications
• Effective Date: 01-Jul-2004
• Refers: ASTM B584-00 - Standard Specification for Copper Alloy Sand Castings for General Applications
• Effective Date: 10-May-2000

Overview

ASTM F956-91(2023), Standard Specification for Bell, Cast, Sound Signalling, sets requirements for the design, material, performance, and inspection of cast bells and mounting hardware used as sound-signalling devices on ships, boats, and other marine craft. This standard ensures compliance with the International Regulations for Preventing Collisions at Sea (Colregs), supporting safety through effective audible warning mechanisms.

The standard outlines requirements for bell sizes, materials, acoustic performance, and installation, helping shipbuilders, marine suppliers, and vessel operators to manufacture, select, and maintain sound-signalling bells that meet international maritime safety requirements.

Key Topics

• Material Requirements

  • Bell bodies, clappers, and cast fittings must be made from copper alloy, ensuring corrosion resistance suitable for marine environments.
  • All auxiliary fittings (bolts, nuts, washers, pins, supporting lugs) must use copper alloys compatible with the bell castings.

• Bell Sizes and Dimensions

  • Bells are classified by bell mouth diameter, ranging from 150 mm for small craft to 550 mm for the largest vessels.
  • Bulkhead mounting plates are specified for smaller bells (150 mm and 200 mm).
  • Precise dimensional tolerances, mass allowances, and clapper-to-bell mass ratios are defined for consistent manufacturing and performance.

• Acoustic Performance

  • Bells must produce a full, clear, round, and far-reaching tone, with a sound pressure level of at least 110 dB measured at 1 meter, meeting regulations for maritime audible signals.
  • Acoustic tests are required for 200 mm heavy and larger bells to verify compliance with the prescribed sound level.

• Workmanship and Appearance

  • Bells must be free from cracks, burrs, and other defects. A polished finish is required on exterior and functional interior parts.
  • Product markings include owner’s inscriptions, ASTM specification numbers, and may also feature manufacturer branding.

• Inspection, Testing, and Packaging

  • Each bell is inspected for conformity with dimensional, mass, and acoustic requirements.
  • Packaging guidelines ensure bells and clappers are protected during transportation, with additional provisions for military or overseas shipments.

Applications

ASTM F956-91(2023) sound-signalling bells are essential for:

• Compliance with International Regulations for Preventing Collisions at Sea (Colregs), which mandate sound-signalling devices on vessels over 12 meters.
• Use as primary sound signals on commercial ships, naval vessels, passenger ferries, and recreational boats.
• Installation on deck areas for general signaling, watch, fire, or emergency alarms.
• Ensuring regulatory approval for marine equipment, supporting both vessel certification and operational safety requirements.
• Marine refit and maintenance programs, where replacement or inspection of sound-signalling devices is required.

Suitable bell sizes based on vessel length include:

• 150 mm and 200 mm for small craft and boats under 12 meters.
• 200 mm and 250 mm for boats 12-20 meters and submarines under 100 meters.
• 300 mm and larger for ships over 20 meters, with the largest sizes specified for vessels exceeding 150 meters in length.

Related Standards

Organizations should reference the following related standards and documents:

• ASTM B584: Specification for Copper Alloy Sand Castings for General Applications - referenced for material requirements.
• CFR 33 Part 81–72 and Part 86: U.S. Coast Guard implementing rules and technical details for shipboard sound signals.
• COLREGs: International Regulations for Preventing Collisions at Sea, Annex III - technical specifications for sound signaling on vessels.
• MIL-STD-129: Military standard for marking shipments and storage, relevant for defense procurement.

ASTM F956-91(2023) provides the international basis for consistent, reliable, and regulatory-compliant marine sound-signalling bells. Adherence to this standard helps ensure maritime safety and facilitates equipment approval in global shipping operations.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F956 − 91 (Reapproved 2023) An American National Standard
Standard Specification for
Bell, Cast, Sound Signalling
This standard is issued under the fixed designation F956; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This specification covers cast sound-signalling bells, 3.1 Definitions:
together with bulkhead mounting plates for the smaller bells, 3.1.1 bell, n—a hollow metal instrument that rings when
for use on ships, boats, and other marine craft, for compliance struck.
with the rules in the convention on the International Regula-
3.1.2 cast, v—to form by molding in a hollow form for
tions for Preventing Collisions at Sea (commonly called
shaping a liquid or plastic substance.
Colregs). See Appendix X1.
3.1.3 clapper, n—hammer like object inside a bell.
1.2 Bells and bulkhead mounting plate shall be sized as
4. Classification
indicated in Section 4 (see Appendix X2).
4.1 Bells shall be furnished in the following sizes, based on
1.3 For consistency with International Regulations, all mea-
bellmouth diameter in millimetres (see Appendix X2):
surements are in SI units.
4.1.1 150 mm,
1.4 The values stated in SI units are to be regarded as
4.1.2 200 mm (2.2 kg),
standard. No other units of measurement are included in this
4.1.3 200 mm (4.5 kg),
standard.
4.1.4 250 mm,
1.5 This international standard was developed in accor-
4.1.5 300 mm,
dance with internationally recognized principles on standard-
4.1.6 360 mm,
ization established in the Decision on Principles for the
4.1.7 400 mm, and
Development of International Standards, Guides and Recom-
4.1.8 550 mm.
mendations issued by the World Trade Organization Technical
4.2 Bulkhead mounting plates shall be furnished for the
Barriers to Trade (TBT) Committee.
following bell sizes:
2. Referenced Documents 4.2.1 150 mm, and
4.2.2 200 mm.
2.1 ASTM Standards:
B584 Specification for Copper Alloy Sand Castings for
5. Ordering Information
General Applications
2 5.1 Orders for materials under this specification shall in-
2.2 Other Documents:
clude the following information:
CFR 33 Part 81–72 Implementing Rules
5.1.1 ASTM designation and year of issue.
CFR 33 Part 86, Subpart B, Bell or Gong
5.1.2 Number of bells.
5.1.3 Size of bell(s) (see 4.1).
5.1.4 Additional bulkhead mounting plates (see 4.2 and
6.2.2).
5.1.5 Inscription required (see 12.1).
5.1.6 Packaging, if other than commercial (see Section 13).
This specification is under the jurisdiction of ASTM Committee F25 on Ships
and Marine Technology and is the direct responsibility of Subcommittee F25.07 on
6. Materials and Manufacture
General Requirements.
Current edition approved May 1, 2023. Published May 2023. Originally
6.1 Material:
approved in 1986. Last previous edition approved in 2018 as F956 – 91 (2018).
6.1.1 Bell bodies, clappers, and other cast fittings and parts
DOI: 10.1520/F0956-91R23.
shall be copper alloy conforming to Specification B584, UNS
Available from DLA Document Services, Building 4/D, 700 Robbins Ave.,
Philadelphia, PA 19111-5094, http://quicksearch.dla.mil.
C87200.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
6.1.2 Fittings such as bolts, nuts, washers, pins, and sup-
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
porting lugs shall be of copper alloy compatible with the bell
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. castings.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F956 − 91 (2023)
Mass and Dimensions of Bells
Bell Size, Bell Mass, Dimensions, mm
mm kg A B NOTE 1—All dimensions in millimetres.
150 1.4 150 105 Tolerances:
200 2.2 200 133
Up to 125 mm: 62 mm
200 4.5 200 152
Over 125 mm: 63 mm
Mass of bell: 9 kg 6 0.45 kg.
NOTE 1—All dimensions in millimetres.
Mass of Clapper: 0.5 kg 6 0.05 kg.
Tolerances:
FIG. 2 Size 250
Up to 150 mm: 62 mm
Over 150 mm: 63 mm
Mass of Bell: 60.2 kg (60.3 kg for 4.5 kg bell).
the bell, shall have a smooth polished finish. The “visible” part
Mass of Clapper: No less than 3 % of bell mass.
of the clapper shall have a similar finish.
FIG. 1 Sizes 150 and 200
10. Sampling
10.1 For orders for 1 or 2 bells of the same size, each bell
6.2 Manufacture:
shall be inspected and tested.
6.2.1 Construction shall be in accordance with Fig. 1, Fig. 2,
and Fig. 3.
10.2 For orders for 3 to 10 bells of the same size, 2 bells
6.2.2 For Fig. 1 and Fig. 2, one bulkhead mounting plate
shall be selected at random. If any one of them fails to meet the
shall be furnished with each bell, however, additional mount-
requirements, then all bells in the order shall be inspected and
ing plates may be ordered.
tested.
6.2.3 For all bells, two extra supporting nuts, washers, and
10.3 For orders for more than 10 bells of the same size.
acorn nuts (where used) shall be furnished.
They shall be separated into groups of 10 (or fraction thereof)
for sampling purposes.
7. Acoustic Requirements
7.1 Bells shall have full, clear, round, and far reaching 11. Inspection and Testing
tones. The sound pressure level shall not be less than 110 dB at
11.1 Responsibility—Unless otherwise specified in the
a distance of 1 m from it.
order, the manufacturer is responsible for the performance of
all inspection requirements specified herein. The manufacturer
8. Dimensions, Mass, and Permissible Variations
may utilize his own facilities or any commercial facilities
8.1 Dimensions and mass of bells, together with tolerances,
acceptable to the purchaser. The purchaser reserves the right to
shall conform to Fig. 1, Fig. 2, and Fig. 3.
perform any of the inspections set forth in this specification
where such inspections are deemed necessary to assure that
9. Workmanship, Finish, and Appearance
supplies conform to the prescribed requirements. Nonconform-
9.1 Bells shall be free of cracks, burrs, sharp cutting edges, ing bells shall not be offered for delivery.
adhering sand, and other defects and blemishes affecting their
11.2 Inspections:
life, appearance, and serviceability.
11.2.1 The dimensions of the bell and appurtenances shall
9.2 Bell exteriors and the lower part of the interior, from the be checked to ensure that they are within the specified
bellmouth to 10 mm above the line where the clapper strikes tolerances.
F956 − 91 (2023)
Dimensions of Bells, mm
Bell Size A B C D E F G H
300 300 270 50 65 25 208 310 M16 × 2
360 360 320 55 85 30 259 370 M20 × 2.5
400 400 350 60 100 30 291 405 M24 × 3
550 550 475 90 130 35 399 540 M24 × 3
Mass of Bells, kg
Bell Clapper
Bell Size
Mass Tolerance Mass Tolerance
300 14 ±0.70 0.60 0.04
360 27 ±1.35 0.95 0.07
400 34 ±1.7 1.35 0.09
550 90 ±3.6 3.40 0.18
NOTE 1—All dimensions in millimetres:
Tolerances:
Up to 125 mm: 62 mm
125 to 250 mm: 63 mm
250 to 375 mm: 65 mm
375 to 500 mm: 66 mm
Over 500 mm: 610 mm
FIG. 3 Size 300 and Above
11.2.2 The bell, without bracket or mounting plate (for 11.3.1 The sound, produced in accordance with Appendix
150 mm and 200 mm light), and clapper shall be weighed X1.1, shall be measured in a space with no large sound
separately to ensure that the mass is within the specified reflecting surfaces (except the floor) that are within 10 m. The
tolerance. sound shall be measured using a commercial sound level meter
11.2.3 For the 150 and 200 light sizes, the brackets shall be located at a distance of 1 m and at a height above the floor
engaged and disengaged from each of the mounting plates to equal to that of the striking point.
ensure portability.
12. Product Marking
11.3 Acoustic Tests—Acoustic tests shall be conducted only
for the 200 mm heavy and larger bells to check the require- 12.1 Owner’s inscription shall be as specified. It shall be
ments of 7.1. Each bell tested shall be supported by the yoke or applied either by being cast in relief (raised) or by engraving.
eyebolt with the clapper in place. The bell shall be rung by Size and location shall be the same as U.S. shown in Fig. 1,
striking the bell with the clapper, activated by a lanyard. Fig. 2, and Fig. 3.
F
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