January 2008: Property Loss Prevention in Glass Manufacturing Plants
There are various types of glass manufacturing plants, and the processes and associated hazards differ significantly. One thing they have in common is that business interruption potential is higher than other types of occupancies, since the glass plants typically operate continuously for years.
The glass forming operation, if applicable, can present the greatest fire hazard within the operations since significant quantities of lubricating oils, mold release oils or combustible binders can be handled near the glass furnaces that are operated at high temperatures.
We address below some loss prevention issues that are critical for glass manufacturing plants such as Utilities, Construction, Operation, and Automatic Fire Protection.
Utilities
Since glass furnaces are operated continuously for years, reliability of the related utilities is the key issue. A minor event such as damage on a main power supply cable can stop production for the entire plant, and can result in a longer-than-expected business interruption if the remaining glass is not drained out from the furnaces in a timely manner.
Redundancy of the production and utility equipment
Single loss of any piece of production or utility equipment should not stop
the production for an extensive time. The plant should be designed based
on "N+1 philosophy" (i.e., at least one back-up utility or critical
piece of equipment should be available at any time).
Oil insulated transformers should be separated by fire walls if they are grouped so that they will not expose each other and will not be lost in single fire event.
Back-up tanks for natural gas or LPG (for running the glass furnaces) should be preferably installed on site to prepare for a potential interruption although having tanks on site will present a fire or explosion hazard. They should be installed with adequate separations from the important buildings or structures and placed parallel to the main plant.
Maintenance
Plant power supply systems should be inspected and maintained properly.
Infrared surveys have been proven very effective to find potential problems
and should be conducted annually for key electrical equipment items. In
some plants, high voltage power cables should also be inspected for their
entire length.
Preparation for emergencies
A power outage can still occur for well designed and redundant power supply
systems. In case of such an event, glass furnaces should be shut down safely.
To do so, all associated utilities should be operable (such as cooling air
systems, cooling water systems, process or temperature control instruments,
pollution abatement, waste water treatment, etc.). The emergency power capacity
and duration should be studied well in advance. The emergency generators
should be tested at least monthly under a full load.
Emergency procedures for shutting down or inspecting utilities should also be prepared for other possible events such as fire, earthquake, flood and hurricane, etc. Training should be conducted based on pre-planning.
Others
Pollution abatement systems, through which the burnt natural gas or LPG
will be treated before releasing to the atmosphere, are mandated in most
countries. They are typically taller than other buildings or structures
and can be damaged if they are not properly designed against the expected
wind-speeds, or they can catch fire if the insulation materials are of combustibles.
A fire can damage waste water treatment facilities if there are combustible construction or contents (i.e., tanks, etc.). Gas detection is recommended where flammable gas can be generated from waste water.
If these facilities are lost or damaged, the authorities having jurisdiction may not allow the plant operations to be continued. Back up plans should be made in advance to prepare for the possible scenarios.
Construction
The temperature of glass furnaces can be operated as high as 1,400°F (760°C) which is high enough to ignite combustibles if used for building construction.
Building construction
Where glass furnaces are installed, the building construction should be
non-combustible. Fire ratings should be determined based on the equipment
arrangements and code requirements, if applicable.
Molten glass
Molten glass, if released from the glass furnaces, can expose the steel
members or legs of the furnaces themselves, and surrounding occupancies
especially the gas manifolds, safety equipment, and combustion controls.
Bunds should be provided underneath and adjacent to the glass furnaces in
order to confine the whole volume of a molten glass spill. Legs or any other
steel members within the bunds should be fireproofed and process equipment
should not be located within the bund areas.
Gas
Oxygen fuel headers should also be protected from molten glass.
Operations
Glass furnaces are a special item that can be only found in glass manufacturing plants. They are run mostly by oil or gas.
Combustion Control
The glass furnace should be provided with the basic combustion controls
like any other furnaces such as manual shut-off valves, gas pressure regulators,
safety shut-off valves (SSOV), high or low gas pressure switches and combustion
controls.
Inspection/maintenance/monitoring
Refractory is made of ceramic materials designed to resist high temperatures
over an extended period of time. It looks like a brick and is used in the
furnace enclosures for insulation purposes. The refractory should be visually
inspected daily to find hot spots and other problems. Some plants use thermographic
(infrared) cameras for inspections. If there is a developing weakness in
the refractory, the adjacent area can be directly exposed to very high temperature.
The refractory temperatures should be continuously monitored with thermocouples
and should send an alarm when abnormal conditions are found. Loss of or
insufficient cooling air or water should also send an alarm.
Cleaning
Combustible residues, created due to the forming operations, should be cleaned
up on a regular basis. The frequency of cleaning depends on the amount of
residue.
Automatic Fire Protection
Like any other manufacturing plants, automatic sprinklers (or other types of automatic fire suppression systems) are necessary wherever combustibles/flammables are stored or handled. They are typically found in the following areas.
1) Glass forming operation areas where lubricating oils, mold release oils
or combustible binders are used.
2) Warehouse areas where packaging materials or finished goods are stored,
and oil storage areas.
3) Electrical rooms or areas where the cable concentration is high. Cable
coating is an alternative.
4) Emergency generator rooms.
5) Other areas where the combustible loading warrants.
6) LPG tanks and oil insulated transformers should be protected by automatic
water spray systems.
7) Cooling towers if fill materials are combustible.
8) Office areas and other general plant areas.
Risk Logic has the capability to evaluate property loss prevention risks and recommend ways to improve them in glass manufacturing facilities.