Document ID: OSHA-2008-0034-0014
Agency: osha
Document Type: Supporting & Related Material
Title: 
Posted Date: 2009-08-24T04:00Z

Exhibit No. OSHA-2008-0034-0014

Substantial Differences Between NFPA 51A-2001 and CGA G-1.4-1966:

Additions and Revisions

Section No. in NFPA 51A-2001	

Description of Section

1.2.1	States that the standard covers every plant engaged in the
generation and compression of acetylene and charging acetylene
cylinders, while section 1.2.1 of CGA G-1.4-1966 states that the
standard covers the same types of plants, but only for plants
constructed after the issue date of the standard.

1.2.2	Allows plants not in strict compliance with the standard to
continue acetylene operations when the operations do not endanger
employees or property.  Section 1.2.5 of CGA G-1.4-1966 states that
existing plants that meet the “intent” of the standard may continue
to operate when authorized to do so by the authority having
jurisdiction.

1.3	Adds definitions for the following terms:  “High Pressure
Acetylene,” “Low Pressure Acetylene,” “Medium Pressure
Acetylene,” “Approved,” “Authority Having Jurisdiction,”
“Limited-Combustible Material,” “Listed,” “Mobile Acetylene
Trailer System,” “Shall,” and “Should.”  This section provides
a more detailed definition for “Noncombustible Material” than
section 1.3 of CGA G-1.4-1966, and specifies “windows, glazed with
safety glass or wired glass” in the definition of “Unpierced
Wall,” while this definition in section 1.3 of CGA G-1.4-1966 refers
only to “windows.”

2.1.2	States that the authority having jurisdiction must determine the
requirements for distances, barriers, and other protective measures for
plants located in heavily populated or congested areas, while section
2.1.1 of CGA G-1.4-1966 requires that plants be in industrial,
agricultural, or equivalent areas.

2.2.1	Adds a new section specifying requirements for separating portions
of a plant used for both acetylene operations and charging operations
involving other gases.

2.2.2	Adds a new section specifying requirements for separating portions
of a plant used for acetylene operations from portion of the plant that
do not meet the design and construction requirements of standard.

2.3.1	Allows use of limited-combustible materials in walls, partitions,
and roofs of buildings used for acetylene operations, while section
2.2.3 of CGA G-1.4-1966 permits only noncombustible materials.

2.3.2	Specifies less detailed explosion-venting requirements for
buildings and rooms used for acetylene operations (but not
calcium-carbide storage) than section 2.2.2 of CGA G-1.4-1966.

2.3.3	Refers to NFPA 101 for exit requirements, while section 2.2.4 of
CGA G-1.4-1966 requires that exits be “readily accessible in case of
emergency and shall open outward.”

2.4	Specifies more detailed ventilation requirements than section 2.3.1
of CGA G-1.4-1966.

2.6.1	Unlike section 2.5.1 of CGA G-1.4-1966, this section (1) does not
require that unpierced walls in rooms containing general-purpose
electrical equipment be made of noncombustible material, and (2) for
existing plants, permits walls in these rooms to have self-closing
doors.

2.6.2	Requires that electrical equipment in rooms housing acetylene
operations must conform to the Class 1, Division 2 requirements of NFPA
70, while sections 2.5.2 and 2.5.3 of CGA G-1.4-1966 specifies that this
classification applies to acetylene equipment with liquid seals, relief
valves, and drain lines when this equipment is vented outdoors.  When
this equipment is not vented outdoors, Class 1, Division 1 requirements
apply.  In addition, both sections of CGA G-1.4-1966 explicitly require
that electrical equipment be approved for Class 1, Group A, B, C, or D
services.

2.6.3	Adds a new requirement that emergency electrical-shutdown switches
be readily accessible at the building exists to deenergize compressors
and generators.

3.1.1	Specifies that packages used to store calcium carbide meet
Department of Transportation (U.S. or Canada) regulations.  Section
3.1.1 of CGA G-1.4-1966 specifies that the packaging be metal containers
that will not rupture, and also are watertight, during normal handling.

3.2.6	Adds a provision to section 3.2.6 of CGA G-1.4-1966 permitting the
storage of unopened calcium-carbide containers that are covered with ice
and snow in rooms or buildings devoted exclusively to the storage of
calcium carbide in drums.

3.2.7	Adds a new section requiring that calcium carbide stored inside
buildings must be in a dry, waterproof, and well-ventilated area.

3.3	Adds a new section specifying that areas used for transferring
calcium carbide from transport containers to generator-hopper loading
carts/systems be protected from rain.

4.3.3	Requires that vent pipes terminate in a hood or bend directed to a
safe location at least 12 feet above ground, 3 feet from combustible
construction, and as far as practicable from building openings and
ignition sources.  Section 4.2.3 of CGA G-1.4-1966 requires that vent
pipes terminate at least 3 feet outside a building, 12 feet above
ground, and 25 feet from an ignition source and combustible materials.

4.3.4	Adds a requirement to section 4.2.4 of CGA G-1.4-1966 that
specifies the cross-sectional area of a common vent pipe.

4.5.2	Revises section 4.4.3 of CGA G-1.4-1966 by decreasing from 25 feet
to 15 feet the minimum distance between an ignition source and the point
at which calcium-carbide residue discharges from a receptacle, but added
a requirement that these discharges must be at least 15 feet from
adjoining property that is suitable for building.

5.1.2	Adds a requirement to section 5.1.1 of CGA G-1.4-1966 that
gasholders must be at least 25 feet from adjoining property that is
suitable for building or a public way.

5.1.3	Requires that the location of gasholders comply with section 2 of
the standard, while section 5.1.3 of CGA G-1.4-1966 specifies compliance
with section 2 of that standard.  See the descriptions of the
differences between these sections above in this table.

6.1.2	Revises section 6.1.2 of CGA G-1.4-1966 by adding driers to the
list of equipment in high-pressure systems that must have drain lines
piped outdoors, and requiring that these drain lines not be near
combustible material.  Also added a provision that drain lines from
medium-pressure systems may be piped to indoor drains when “the
effluent water is visible to the operator at the drain valve
location.”

6.1.3	Revises section 6.1.3 of CGA G-1.4-1966 by requiring that
pressure-relief-valve vent pipes terminate in a hood or bend that is
directed to a safe location at least 12 feet above ground, 3 feet from
combustible construction, and as far as practicable from building
openings and ignition sources.  Section 6.1.3 of CGA G-1.4-1966 requires
vent pipes to terminate at least 3 feet outside a building, 12 feet
above ground, and 25 feet from an ignition source and combustible
materials.

6.2.3	Adds a requirement to section 6.2.3 of CGA G-1.4-1966 specifying
requirements for temperature indicators on final-discharge piping.

6.2.4	Adds a requirement to section 6.2.4 of CGA G-1.4-1966 establishing
the gauge pressure for pressure-relief devices in the final compression
stage.

7.1.3	Requires that pipe fittings conform to sections 10.1.1 through
10.1.3 of the standard, while section 7.1.3 of CGA G-1.4-1966 specifies
compliance with sections 9.2.1, 9.2.2, and 9.2.3 of that standard.  See
the descriptions of the differences between these sections below in this
table.

7.3.2	Revises section 7.3.2 of CGA G-1.4-1966 to require that pipe
having a nominal size of one inch (instead of three-quarters inch) be at
least Schedule 80.

7.3.3	Revises section 7.3.3 of CGA G-1.4-1966 to require that pipe
having a nominal size of one and one-quarter inch to one and one-half
inch (instead of one inch to one and one-half inch) be at least Schedule
160.

7.3.6	Adds a new section specifying requirements for pressure gauges
exposed to detonation flames when the gauges serve piping exceeding 15
psi.

7.4	Revises section 7.4.1 of CGA G-1.4-1966 to require that the minimum
burst rating for cylinder-charging leads be 10,000 psi instead of 6,000
psi.

8.1.3	Adds a new section specifying requirements for pressure gauges
exposed to detonation flames when the gauges serve cylinder-charging
manifolds.

8.2	Adds a provision to section 8.2.1 of CGA G-1.4-1966 requiring that
the construction and installation of acetone storage containers comply
with NFPA 30.

8.3.1	Adds a new section specifying maximum pressure values based on
acetylene temperatures.

8.3.2	Adds a new section specifying procedures for operating valves at
the start and completion of charging operations.

8.4	Adds a new section on requirements for cooling cylinders connected
to charging manifolds.

8.5	Specifies that charged cylinders be stored outside the charging
room, while section 8.1.6 of CGA G-1.4-1966 requires that storage areas
for these cylinders be “as far as practicable from the charging
manifolds.” 

9.2.1	Requires at least one 1-1/2 inch hose station for plant areas used
for acetylene operations (but not for calcium-carbide storage), while
section 9.1.3 of CGA G-1.4-1966 requires that fire hoses, water
sprinkler systems, and dry-chemical or carbon-dioxide fire extinguishers
be provided for these plant areas.

9.2.2	Adds a new section on determining the need for automatic
water-spray systems for fire protection.  This section also includes
requirements for installing and actuating these systems, water-coverage
requirements, and using an extra-hazard, open- or closed-head sprinkler
system as an alternative.

9.2.4	Adds an option to section 9.1.4 of CGA G-1.4-1966 allowing fire
hoses and sprinkler-actuation valves to be located and operated at an
exit, as well as outdoors.

9.2.5	Adds a requirement to section 9.1.7 of CGA G-1.4-1966 that each
plant have a written emergency procedure and conduct periodic fire
drills.

10.1.3	Requires that equipment and piping used in acetylene operations
be electrically continuous and bonded to a grounding electrode as
specified by NFPA 70, while section 9.2.3 of CGA G-1.4-1966 requires
that such equipment and piping be electrically grounded.

Substantial Differences Between NFPA 51A-2001 and CGA G-1.4-1966:

CGA G-1.4-1966 Sections Not Available in NFPA 51A-2001

Section No. in CGA

G-1.4-1966	

Description of Section

1.2.2 and 1.2.3	Specifies requirements when plants have both acetylene
operations and other operations involving compressed gases.

2.1.1	Requires that acetylene plants be located in industrial or
agricultural areas, or equivalent areas.

5.3.1	Specifies that purifiers and driers must be designed to prevent
excessive pressure within equipment, or to have pressure-relief devices.

8.1.3	Specifies that cylinder-charging manifolds must have a pressure
gage located downstream of the shut-off valve.

9.1.1	Requires that plant areas used for acetylene generation and
calcium- carbide storage must have available an adequate supply of dry
sand and/or dry-chemical and carbon-dioxide fire extinguishers.

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