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8/10/2019 Effective Fire Protection for Transformers
http://slidepdf.com/reader/full/effective-fire-protection-for-transformers 1/43
Transformer Deluge SystemsTransformer Deluge Systems
8/10/2019 Effective Fire Protection for Transformers
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How Do Transformer Fires Ignite?How Do Transformer Fires Ignite?
Common causes of transformer failure:
• Weather-related events such as lightning
• Short circuits in electrical equipment
• The most common cause is breakdowns
in the insulation system
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Implications of a Transformer FireImplications of a Transformer Fire
Destruction of equipment such as:
• Overhead conductors
• Buses
• Cable trays
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Implications of a Transformer FireImplications of a Transformer Fire
Transformers can rupture during a failure, releasing oi l into the area
• Risk is amplified substantially• Fire can spread to other areas of the facility
• Oil can overflow from the collection basins if discharge is not calculated
correctly or containment pits are not the appropriate size
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Implications of a Transformer FireImplications of a Transformer Fire
Plant is taken offline, resulting in
revenue losses
Lives of employees and building
inhabitants are put at risk
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Why are Effective Fire ProtectionWhy are Effective Fire Protection
Systems Important for Transformers?Systems Important for Transformers?
Implementing and maintaining an effective fire protection
system for transformers should be a priority for power
generating facil ities for many reasons:
• Industry requirements – NFPA, insurance
and even environmental authorities in some
instances require facilities to take specificmeasures to meet fire protection standards
for transformers
• Life safety – fire protection systems can
help protect on-site employees from the
hazards of potentially violent and
explosive transformer fires
• Loss prevention – controlling transformer fires can prevent the loss of
millions of dollars that is associated with the destruction of adjacent
equipment and unplanned outages
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What is a Deluge Water Spray System?What is a Deluge Water Spray System?
NFPA-850: Recommended Practice for Fire
Protection for Electric Generating Plantsand High Voltage Direct Current Converter
Stations
Identification of and Protection Against Hazards - Transformers
Oil filled main, station service and start-up transformers not meeting
the separation or fire barrier recommendations or as determined bythe Fire Protection Design Basis should be protected with automatic
waterspray or foam-water spray systems.
8/10/2019 Effective Fire Protection for Transformers
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What is a Deluge Water Spray System?What is a Deluge Water Spray System?
NFPA-15: Standard for Water Spray FixedSystems for Fire Protection
Defines a water spray system as:
“an automatic or manually actuated fixed pipe system
connected to a water supply and equipped with waterspray nozzles designed to provide a specific water
discharge and distribution over the protected surfaces or area”.
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What is a Deluge Water Spray System?What is a Deluge Water Spray System?
NFPA-15: Standard for Water Spray FixedSystems for Fire Protection
Design of systems can vary considerably• Must consider the nature of the hazard and basic
purpose of protection
• There are a wide variety of nozzles with different spray
characteristics
• It is essential that the designer understand the limitations
and capabilities of the systems
• Design density is typically .25 GPM over the entire
surface area of the transformer
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How Does a Deluge System Work?How Does a Deluge System Work?
The Deluge Valve is an integral part
of a deluge system
• Specialty fire protection valve
• Holds water supply back behind a
clapper or diaphragm
• Water is released via an electric or
pneumatic detection system
Deluge ValveDeluge Valve
Water is released through open nozzlesWater is released through open nozzles
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How Does a Deluge System Work?How Does a Deluge System Work?
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Where to Begin?Where to Begin?
What is the available water supply?
• Fire pump flow test• Hydrant flow test
• Available pressure and flow at the base of the riser
Determine the location of existing transformer delugevalves and routing of existing feed mains
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Where to Begin?Where to Begin?
Consider existing pipe stand foundations
• Will the existing locations suit new
transformer dimensions?
• Are they reusable? (Consult with Plant
Structural Engineers)
Are there currently or will there be firewalls to isolate each fire area?
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Where to Begin?Where to Begin?
What is the ground below the
transformer?• Absorbing pit with stone fill
or
• Non-absorbing with exposed
concrete containment
Obtain any specific electrical
clearance requirements based
on Basic Impulse Level (BIL)as specified in NFPA-15 or
other specific requirements
defined by Owner
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Design of Deluge SystemsDesign of Deluge Systems -- NozzlesNozzles
The layout of nozzles isbased upon spray
characteristics:
• Angle of spray andassociated positioning angle
• Orifice size (how much
water can be sprayed out of each nozzle
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Design of Deluge SystemsDesign of Deluge Systems -- NozzlesNozzles
Nozzles are positioned to
provide complete water
spray impingement on allexposed exterior surfaces,
such as:
• Radiators• Conservator tank
• Electrical cabinets, etc
Water spray should not
envelop energized
bushings or lightning
arrestors by directimpingement.
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Typical NozzlesTypical Nozzles
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Spray Pattern DesignSpray Pattern Design
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Design of Deluge SystemsDesign of Deluge Systems – – Pipe SupportPipe Support
Pipe support options
• Can fire walls or other structural elements be
utilized for support?
• Are there existingfoundations for pipe
stands or are new ones
required?
• Must locate stands to
avoid interferences with
cabinets, door swings, etc.
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Design of Deluge SystemsDesign of Deluge Systems – – Piping LayoutPiping Layout
Piping Layout Considerations
• Transformer height dictates howmany “rings” are required
• Rings are typically located around
the transformer with the possibilityof additional piping between
transformer casing and radiators
• Avoid locating piping withincabinet door swings
• Design with consideration for
future maintenance access
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Design of Deluge SystemsDesign of Deluge Systems – – Piping LayoutPiping Layout
Piping Layout Considerations
• Avoid running piping across the
top of the transformer tank
• Determine electrical
clearance requirements and locate
piping the proper distance
• Route piping so that it facilitates
automatic draining through open
nozzles
• Determining the connection to
mains
• Designing for effective drainage
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Design of Deluge SystemsDesign of Deluge Systems -- BracingBracing
Bracing: significant forces are
incurred when a deluge valve trips
• Piping must be braced to resist
these forces. Bracing is usually
provided at:
Corners of the main loop
Drops and/or rises more than 4’
• Bracing consists of pipe clamps
and swivels attached to steel
bracing pipe
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Design of Deluge SystemsDesign of Deluge Systems -- DetectionDetection
Electric Detection
• Can an existing releasing panel be
utilized or is a new one required?
• Which type of electric detection is to
be utilized?
Spot Type Heat Detectors
Linear Protect-O-WireProtectowireProtectowire Linear Linear
Heat Detector Heat Detector
SpotSpot--TypeType
ElectricElectric
DetectionDetection
VERTICAL DETECT-A-FIRE UNITS
(Hexagonal Head)
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Design of Deluge SystemsDesign of Deluge Systems -- DetectionDetection
Pneumatic Detection
• Utilize dry pilot sprinkler head
• Air supply – plant air or local air compressor?
• Which type of electric detection is to be utilized?
Implementing Alarm Systems
Manual Release stations to be provided at
hazard area?
New Notif ication Appliances such ashorn/strobe units to be used?
Dry pilotDry pilotsprinkler sprinkler
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DesignDesign – – Drawings and DocumentationDrawings and Documentation
• Preparation of material data
sheets for Owner’s approval
of equipment to be utilized
• Development of a
preliminary design
drawing showing nozzle
locations, pipe routing and
support locations along with
initial detailing
• Hydraulic calculations are
performed for pipe sizing
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DesignDesign – – Drawings and DocumentationDrawings and Documentation
• Electrical drawings showing detection
and alarm devices along with
preliminary wiring diagrams
• In some instances a partial design is
submitted for Owner review and
comments
• Owner comments would then be
incorporated into the design packagesubmittal for approval
D i 3D A i ti
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DesignDesign – – 3D Animation3D Animation
PP C t ti Pl iC t ti Pl i
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PrePre--Construction PlanningConstruction Planning
Scheduling
Assist owner in schedule
development to be sure all activities
are captured and correct durationsare utilized
PP C t ti Pl iC t ti Pl i
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PrePre--Construction PlanningConstruction Planning
Scope
• Meet with Project Manager to verify scope and ensure all aspects ofconstruction are discussed so that everyone is on the same page
• Identify and plan for any required pre-outage work
• Verify that the Owner is aware of items and services that are expected
to be Owner-provided:
Materials and equipment
Labor and services such as electrical install, painting, excavationand backfilling, etc.
Construction-related requirements such as aerial lifts, scaffolding,
laydown requirements, job trailers, etc.
PP C t ti Pl iC t ti Pl i
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PrePre--Construction PlanningConstruction Planning
Safety
• Prepare a job safety analysis for
specific work activities
• Review installation sequence in
detail with Owner’s project managerand field superintendent
I t ll tiI t ll ti
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InstallationInstallation
Coordination with other activit ies:
• Access to work areas
• Scaffolding erection
• Aerial lift usage
I t ll tiInstallation
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InstallationInstallation
Pre-job briefing:
• Work activities change
• Safety concerns
• Weather
• Jobsite working conditions
change due to the type of
activities being undertaken by
others
InstallationInstallation
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InstallationInstallation
Typical installation sequencing
• Demolition of existing piping
May require partial demolition prior to existing transformer’s removal Other piping may need to be removed after the transformer is removed
• Installation of pipe stands
Coordinate with the rigger for efficient installation
Install as many as possible before the new transformer is rigged
InstallationInstallation
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InstallationInstallation
Typical installation sequencing
• Installation of main “loops” and feed mains Coordinate with the rigger for efficient installation
One or more sides of loop may be able to be installed prior to the
new transformer being rigged into place
• Installation of vertical nozzle piping and swing joints
Some nozzle piping may be made on to loop piping on the ground
to facilitate lifting into place with a crane.
Piping is installed with plugged nozzle outlets to facilitatehydrostatic testing
InstallationInstallation
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InstallationInstallation
Typical installation sequencing
• Hydrostatic testing of all deluge piping at 200 psi• Remove test plugs and install and orientate nozzles
• Install bracing
• Install linear heat detection and/or conduit that may be attached todeluge piping
• Detection system terminations are made at releasing control
panel
InstallationInstallation
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InstallationInstallation
Perform the spray test, also known
as a performance test:
• Typically initiated throughdetection system
• All nozzles are viewed to assure
there are no obstructions
• Water spray patterns are verified
to assure that all surfaces are
adequately protected
• Pressure reading is observed at
remote nozzle to verify system is
putting out the required pressure
determined from hydrauliccalculations
Inspection Testing and MaintenanceInspection Testing and Maintenance
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Inspection, Testing and MaintenanceInspection, Testing and Maintenance
Developing a comprehensive inspection, testing andmaintenance program is essential to:
• Ensuring systems are optimally functional when they are
needed in a fire
• Maintaining compliance with industry, insurance and corporate
standards
• Maximizing the life cycle of fire protection systems
Inspection Testing and MaintenanceInspection Testing and Maintenance
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Inspection, Testing and MaintenanceInspection, Testing and Maintenance
• A deluge system’s ITM program should be developed inaccordance with NFPA 25: Standard for the Inspection, Testing
and Maintenance of Water-Based Fire Protection Systems
• Detection system ITM should follow the requirements set forthin NFPA 72: National Fire Alarm and Signaling Code
• Documentation of all ITM work should be meticulously
maintained and readily available for review by the AHJ
Inspection Testing and MaintenanceInspection Testing and Maintenance
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Inspection, Testing and MaintenanceInspection, Testing and Maintenance
Critical elements of an ITM program include:
• Annual tripping of deluge valve at full flow
• Observation of water discharge patterns to confirm proper
positioning and absence of obstructions
• Verification of water flow alarms
• Pressure readings at the remote nozzle and deluge valve toensure hydraulic design requirements are met
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SummarySummary
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SummarySummary
• A transformer fire is not a frequent occurrence but the impact istremendous
• In a fire the transformer will likely be destroyed immediately but
damage to adjacent equipment/structures can be mitigated
• The consequences of an uncontained fire include:
Costly damage to the facility
Loss of revenue due to an unscheduled outage Compromising the safety of facility inhabitants
SummarySummary
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SummarySummary
Fire protection systems can be effective in minimizing damage if:
Design Construction
Operation Inspection, Testing and Maintenance
are properly executed by an experienced professional with
the required experience.
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Protecting People, Plant and ProductionProtecting People, Plant and Production
www.femoranshs.comwww.femoranshs.com