effective fire protection for transformers

8/10/2019 Effective Fire Protection for Transformers

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Transformer Deluge SystemsTransformer Deluge Systems



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



Implications of a Transformer FireImplications of a Transformer Fire

Destruction of equipment such as:

• Overhead conductors

• Buses

• Cable trays




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




Plant is taken offline, resulting in

revenue losses

Lives of employees and building

inhabitants are put at risk



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



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.




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”.




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



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



How Does a Deluge System Work?How Does a Deluge System Work?



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




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?




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



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



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.



Typical NozzlesTypical Nozzles



Spray Pattern DesignSpray Pattern Design



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.



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



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



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



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)



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



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



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



DesignDesign – – 3D Animation3D Animation

PP C t ti Pl iC t ti Pl i



PrePre--Construction PlanningConstruction Planning

Scheduling

Assist owner in schedule

development to be sure all activities

are captured and correct durationsare utilized





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.





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



InstallationInstallation

Coordination with other activit ies:

• Access to work areas

• Scaffolding erection

• Aerial lift usage

I t ll tiInstallation




Pre-job briefing:

• Work activities change

• Safety concerns

• Weather

• Jobsite working conditions

change due to the type of

activities being undertaken by

others





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






• 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






• 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





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



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





• 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





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



SummarySummary



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



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.



Protecting People, Plant and ProductionProtecting People, Plant and Production

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http://www.femoranshs.com/



effective fire protection for transformers

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