4 Layout Facility Segregation Zoning

8/21/2019 4 Layout Facility Segregation Zoning

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COURSEFACILITIES LAYOUT TRAINING

LAYOUT OF FACILITY –SEGREGATION AND ZONING

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LAYOUT OF FACILITY – SEGREGATION AND ZONING

SUBJECTS

• Safety Distance (SD) and Restricted Area Zone (RAZ)

• Air gap

• Fire zones and divisioning (rating of fire divisions)

• Divisioning/segregation by fire/blast walls or by distance

• Ignition sources ISO 13702

• Equipment Categories as per API 14J

• Hazardous Area Classifications

• Level segregation between liquid and gas hydrocarbons

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SEGREGATION AND ZONING

SAFETY DISTANCE & RESTRICTED AREA ZONE• Ref. Maersk Oil, MODES 01

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SAFETY DISTANCE & RESTRICTED AREA ZONE• Ref. Maersk Oil, MODES 01

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TOTAL, GS EP SAF 213, Impacted area, restricted area and fire

zones, has similar but a bit different criteria for Impacted Area and

Restricted area


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SAFETY DISTANCE & RESTRICTED AREA ZONE

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ThermalRadiation(kW/m²)

Effect

1.2 The sun at noon in summer in northern Europe

2 Minimum to cause pain after 1 minute

< 5 Pain in 15-20 seconds and injury after 30 seconds

> 6 Pain within approx 10 seconds, rapid escape only ispossible

12.5 Significant risk of fatality for medium durationexposure.* Thin steel with insulation on side away from the firemay reach thermal stress level high enough to causestructural failure

25 * Likely fatality for extended exposure and significantrisk of fatality instantly* Spontaneous ignition of wood after long exposure

* Unprotected steel will reach thermal stresstemperature that can cause failure

35 * Cellulosic material will pilot ignite within one minute’sexposure* significant risk of fatality for people exposedinstantaneously


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AIR GAP• Certain equipment may be installed in the air gap

• Air gab is defined in the schematic below:

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AIR GAP• In more general terms, the air gab is given below

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Other provisions:

•

Tolerances for water depth

• Initial penetration into seabed

• Subsidence, etc.


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FIRE ZONES AND DIVISIONING

INTRODUCTION• Main reference is ISO 13702

• Basis for selecting active & passive fire protection is

• Fire and explosion strategy (FES) and fire load analysis

• Evacuation, escape and rescue strategy (EERS) and evacuation

analysis

• Fire loads as part of Dimensioning Accidental Load (DAL as

defined in NORSOK S-001)

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REFERENCES

• IMO SOLAS

• IMO MODU Code

• IMO FTP Code

• MODES 01, Maersk Oil Design Standard, Part 01, Safety Design

• ISO 13702, – Control and mitigation of fires and explosions onoffshore production installations – Requirements and guidelines

• ISO 834-1 – ISO 834-9, Part 1 to 9: Fire resistance tests

• NORSOK S-001, Technical Safety• DNV OS-D301, Fire Protection

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DIVISION INTO FIRE ZONES - PRINCIPLES

• To separate the different fire risk areas from each other

(escalation prevention) – one risk level in one zone

• To ensure a safe escape and evacuation in case of a fire

• Firewater optimization

• Division by distance or by fire wall/deck

• Even a small wellhead platform will require to be divided into at

least 2 fire zones

• First, the wellhead platform will have two different fire risk areas

• secondly a person in one area of the platform will need a second placeto be in case of a fire

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MAIN FIRE ZONING

Requirement for sub-division of a fire zone:

•Size of the zone (m2), among others depending on evacuationrequirements

•Firewater demand for the particular zone.

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MAIN FIRE ZONING - EXAMPLES

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FIRE ZONING – ESDV’S

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• ESDV should be installed where two fire zones interconnect

• The ESDV to be located in the fire zone feeding into the neighbour

zone


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RATING OF DIVISIONS BETWEEN ZONES• The correct selection of fire class depends on two factors:

• Type of fire (cellulosic, hydrocarbon or jet fire)

• Time required with full integrity of the division/wall (depends onescape and evacuation analysis).

• In most cases a time of 60 minutes will be more than sufficient.

• In the first approach, select firewalls for cellulosic fire, i.e. “A”

class divisions.

• Therefore, standard will be A-60 (which in some cases/areas may

be reduced to A-30 or A-15).

• Hydrocarbon fire, heat input > 100 kW/m2 , select H-class

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RATING OF DIVISIONS BETWEEN ZONES• If dimensioning heat input > 150 kW, select J-rating

• For J-rating, a H-60 wall can be conbined with J-15 or J-30 (jet

fire is only relevant for the period of time for blowing down)

• Typically blowdown in 15 minutes

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RATING OF DIVISIONS BETWEEN ZONESTranslation of the ISO 13702, table C.5 nomenclature:

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RATING OF DIVISIONS BETWEEN ZONES

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The table is not symmetrical!

To be read “From” first column areas towards areas in adjacent protected area.


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RATING OF ACCOMODATION DIVISIONS(ref. NORSOK S-001):

• Outer surfaces of LQs shall minimum be A-60

• Heat flux > 100 kW/m2 in a dimensioning fire, minimum class H-60

• No windows in H partitions or walls facing process area

• Fire integrity of bulkheads and decks shall comply with chapter 9of the MODU Code.

• Where MODU Code specifies steel bulkheads internally this shallbe understood as A-0 divisions.

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RATING OF ACCOMODATION DIVISIONS(ref. MODU Code, Table 9):

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SEPARATE ACCOMMODATION PLATFORM• Outer surfaces of LQs shall minimum be A-60

• Barriers as stated in present section should be adhered to

• Rooms containing machinery and flammable fluids such asemergency generators and fire pumps shall be enclosed by

minimum A-60 walls

• The need for H-60 rating of the walls should be evaluated

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EMERGENCY SERVICES(ref. NORSOK S-001, sec. 19.4 ):

• CCR, FW pump systems, emergency power supply with related

distribution equipment and fuel tank shall be protected from the

surroundings by minimum Class A-60 fire divisions.

• Generators (including prime mover), transformers, major

distribution panels, rooms for ventilation equipment and

equipment used for storage of flammable commodities or easily

ignitable material shall be separated from the surroundings of atleast Class A-0 fire divisions.

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FIRE BARRIERS – FIRE/BLAST WALLS OR SEPARATION BY DISTANCE

• Fire barriers may be made by fire rated divisions, i.e. firewalls

with ratings such as A-60, H-60 or similar.

• Division into fire zones may be done both with vertical barriers

(firewalls) and by horizontal barriers (fire rated decks)

• Fire zone division may also be made by distance separation.

• This principle is used when wellheads are located on a separate

platform or if a separate accommodation platform is made.

• Typically this principle requires a bridge of a length of 80 m – 100m.

• Detailed fire load calculations may be used to decide more exactly

on the required bridge length.

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FIRE AND EXPLOSION LOADSFire loads – large pools, large jet fires:

Blast loads:

• Firewalls may need to be rated as blast walls

• Rather open process modules, explosion loads will have amaximum of 0.3 barg.

• This is a value that may be applied in an initial design of modules

and blast walls in modules.

• NORSOK S-001 requires design for 0.7 barg unless more detailed

explosion calculations have been carried out

• The DAL (Design Accidental Loads), must state the loads

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EXAMPLE OF CONCEPTUAL DIVISIONING

Main/Well Intervention DeckA13

A4 A1A8Lower Mezzanine Deck

Roof /Weather Deck

Cellar Deck

WellheadProcess/UtilityAccommodation

27 m

A2A5A9A12

A11

A6A1

0

A14

Flare

A7

Division of platform intofire zones:

A3

H-60/J-15 or J-60

A-60

27 m6 m14 m

Compressors

Plated

Turbines

A16

A15

1 2

Muster area

Life rafts

Sky chute/boardingplatform with life rafts

Utility

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FIREWALL DESIGN• To ensure that flames from one fire zone shall not extend around

the edge of a fire barrier and impinge hydrocarbon containingequipment in the adjacent fire zone, the firewall may need

additional “wings”.• The design may include “wings” to one side, wings to both sides

or extended wings as illustrated in the Figure below.

Firewall

with

"wings"

to

one

side

(horizontal cut through wall)

Firewall

with

"wings"

to

two

sides(horizontal

cut

through

wall)

Extended firewall to ensure that flames from equipment

on

one

side

shall

not

reach

equipment

on

the

other

side

when or if flames from one side of the firewall may go

around

the

edge

of

the

firewall.

extension extension

firewall

firewall

firewall

wing wing

wings

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FIRE INTEGRITY (FIRE CLASS) OF BARRIERS• The traditional and typical fire classes applied for firewalls are:

• Standard fire (cellulosic fire), applicable to A, B and C-ratings

• Hydrocarbon fire applicable to H-ratings when fire load > 100kW/m2.

• The H-rating may be a jet fire rating if this is the design fire case

(fire load > 150 kW/m2).

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THE FIRE TEST CURVES

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IGNITION SOURCES

ISO 13702

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• Chemical reactions

• Oil soaked lagging on hot piping

• Pyrophoric iron sulphide (H2S &

metal corrosion)

• Electrical sparks and arcs

• Electrical motors and generators

•Switches, relays and otherarching components of electricalcircuits

• Electrical wiring mal functioning

•

Electrical welding• Lighting fixtures

• Mechanical sparks

• Lightning


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IGNITION SOURCES

ISO 13702

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• Static electrical sparks

• Fuelling operations

• Filling containers, tanks and

pressure vessels

• High fluid exit velocities (highpressure water sprays, gas jets)

• Drive belt operation

• Shot blasting (velocity)

• Friction

• Flame

• Flaring

• Fired equipment

• Gas welding and cutting

• Hot surfaces

• Fired vessels stacks

•

Engine exhaust

• Heat of compression


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FACILITIES LAYOUT TRAINING COURSE

EQUIPMENT CATEGORIES API 14J


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FACILITIES LAYOUT TRAINING COURSE

EQUIPMENT CATEGORIES API 14J


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AREA CLASSIFICATION

IP 15

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Aim of IP 15• Avoid ignition of those releases that may occur from time to time•

Reduce to an acceptable minimum level the probability of coincidenceof flammable atmosphere and an electrical or other source of ignition• Risk Target is 10-5 year

• IP 15 does not concern major releases (spread of flamables more

than 30 m). These shall be minimised by design and operation to anacceptable residual risk.


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AREA CLASSIFICATION

IP 15

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Zone 0: The part of a hazardous area in which aflammable atmosphere is continuously present or present

for long periods

Zone 1: That part of a hazardous area in which aflammable atmosphere is likely to occur in normaloperation

Zone 2: That part of a hazardous area in which aflammable atmosphere is not likely to occur in normaloperation and, if it occurs, will only exist for a shortperiod.

Non-Hazardous: areas that do not fall into any of theabove. (IS NOT “SAFE AREA”)


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AREA CLASSIFICATION

IP 15 – GRADE OF RELEASE

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Continuous grade release: A release that is continuous or nearly so, orthat occurs frequently and for short periods

Primary grade release: a release that is likely to occur periodically oroccasionally in normal operations, i.e. a release which, in operatingprocedures is anticipated to occur

Secondary grade release: A release that is unlikely to occur innormal operation and, in any event, will do so only infrequently and

for short periods i.e. a release which in operating procedures is notanticipated to occur. Such release may be of unknown size e.g.fracture of a drain or unknown size e.g. corrosion hole.

If it is likely to be present for more than 1000 hours per year.

If it is likely to be present for between 10 to 1000 hours per year.

If it is likely to be present for 1 to 10 hours per year.


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AREA CLASSIFICATION

IP 15

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Continuous grade release Typically Zone 0

Primary grade release Typically Zone 1

Secondary grade release

Typically Zone 2

“Typically” refers that it is ventilation dependent


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AREA CLASSIFICATION

IP 15 - BASIS

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• Natural ventilation and wind without stagnant zones.

•Typically air velocities will not be less than 0.5 m/s and will

frequently be above 2 m/s.

• Where a facility is classified as open area, the hazardous areaclassification of previous slides applies without further ventilation

considerations.

•NB: Risk of reduced natural ventilation – shield/tarpaulins


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AREA CLASSIFICATION

IP 15 – POINT SOURCE METHOD

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AREA CLASSIFICATION


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Natural Gas

Crude –

Unstabilised


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AREA CLASSIFICATION

IP 15 – POINT SOURCE METHOD – FLUIDCATEGORY

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• Condensate and LPG fall under Category A

• Unstabilized crude falls into Category B

• Stabilized crude oil falls into Category C

• Wet and dry gas fall under Category G(i)

• Produced water fall under Category C

• Injection sea water does not require to be classified


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AREA CLASSIFICATION


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Piping:

• Fully welded

• Designed according to ANSI/ASME B31.3

Does not require zoning.


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AREA CLASSIFICATION


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• Flanges:

Secondary grade release source

Broken flanges Primary grade

Ten or more flanges are required within close proximity to createsufficient likelihood of release to justify classification as a secondary

release.

Explains why Fuel gas flange connection to turbines often notclassified


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AREA CLASSIFICATION


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Valves:

Infrequently used

Well maintained

Frequently used(Control valves)

Secondary grade

Additional Primary grade of 0.3 m


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AREA CLASSIFICATION


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Pig Receivers

• Pig receivers are opened frequently and are considered as

primary grade release. The hazardous area should be classified as

zone 1.

• When interlock systems are in place, the release when opening

the launcher/receiver will be minor and a hazard radius of 3 m is

suggested in IP 15.

• If the operating procedures include purging or water washing

before opening the launcher/receiver the hazard radii can be

reduced to 1.5 m.


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AREA CLASSIFICATION


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Pumps

• Secondary grade of release

• Seal leakage rates from standard pumps are generally greaterthan from those pumps fitted with throttle bushes or from high

integrity type pumps.

• A nominal hole size of 2 mm diameter (IP A risk-based approach) canbe taken to represent the leak from a high integrity pump

Note: On multistage pumps, which

normally have a balance line, the seals

will only be subject to a pressurecorresponding to the suction pressure.

The seal pressure for the flushing liquid

is slightly above the pump discharge end

pressure, but this seal pressure will be

lost upon failure of the seal


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AREA CLASSIFICATION


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AREA CLASSIFICATION

IP 15 – PIG RECEIVERS – ED PLATFORM

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AREA CLASSIFICATION - VENTILATION

VENTILATION (HVAC) - OBJECTIVES• Avoid ingress of gas/vapours into unclassified area (overpressure)

• In enclosures with leak sources, to ensure sufficient ventilation toreach zone 2 classification or unclassified area.

• Provide sufficient air changes to remove fumes, etc.

• Separate HVAC systems in hazardous and non-hazardous areasmust be provided.

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Refer to sec. 7, Safety – Safety

Systems for further about ventilation


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LEVEL SEGREGATION

NORSOK S-001

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Fire and explosion evaluations shall be made along with thedevelopment of the layout to minimize the built in escalation

potential. This shall be ensured through the following principles:

• Equipment and piping containing HP gas should be located in theupper decks above the module support frame or main hull.

• Liquid vessels should be located lower than gas equipment

• Low pressure equipment containing large liquid inventories shouldbe located and arranged so that exposure to jet fires isminimised. (BLEVE)

• Hydrocarbon containing equipment shall be protected from

external impact e.g. dropped objects and missiles.

• Confined and congested modules shall be avoided.

• Long narrow modules shall be avoided.

S G G O


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LEVEL SEGREGATION

GUIDE – LEVEL SEGREGATION

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THANK YOU


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THANK YOU

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4 Layout Facility Segregation Zoning

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