20190E00

Il presente documento RISERVATO ed di propriet dell'AGIP. Esso non sar mostrato a Terzi n sar utilizzato per scopi diversi da quelli per i quali stato inviato.This document is CONFIDENTIAL and the sole property of AGIP. It shall neither be shown to third parties nor used for purposes other than those for which it has been sent.

COMPANY SPECIFICATION

OFFSHORE INSTALLATIONS

POSITIONING OF FIRE AND GAS SENSING DETECTORS

20190.VOF.SAF.SDS

Rev. 0

June 1996

0 Emission according to EEC directives STIN SICI STIN 15.6.96REV. DESCRIPTION COMP. VERIF. APPR. DATE

20190.VOF.SAF.SDSRev.0 June 1996Sheet 2


FOREWORD

Rev. 0 Total sheets 36June 1996

This specification supersedes document 07637.GPF.SAF.PRG Criteri diposizionamento ed azioni principali dei sensori di rivelazione per installazionioffshore to which the following modifications have been made:- frame and contents have been updated- listing arrangement of the various sensors have been unified- reference to the specific type of sensor and the actions due to the sensors

activation have been excluded- the expression explosive gas mixture sensors has been replaced with

flammable gas sensors- new smoke sensors have been added into the Conditioning plant room and

into the Control rooms- the standard distinguishing heavy and light gases has been defined- rooms involved by toxic gas sensors have been added- process gas compressor room and its sensors (flame, flammable gas, toxic gas)

have been added- subparagraphs relating to the calculation of distances between sensors (from

NFPA 72A and UNI 9795) have been excluded.



CONTENTS

INTRODUCTION

1. GENERAL

1.1 Scope

1.2 Normative references

1.2.1 European normative references1.2.2 Normative references of ISO, IEC and national organizations1.2.3 Normative references of other organizations1.2.4 Legislation

2. FUNCTIONAL NORMATIVE REQUIREMENT

2.1 Definitions2.2 Operative environment

2.3 Functional requirements

2.3.1 Heat sensors2.3.2 Smoke sensors2.3.3 Flame sensors2.3.4 Flammable gas sensors2.3.5 Toxic gas sensors

2.4 Ergonomics2.5 Safety2.6 Requirements for Quality Management and Quality Assurance

3 SUPPLEMENTARY ELEMENTS

3.1 Enclosure and informative annexes

3.1.1 Informative annexes



INTRODUCTION

This specification takes into consideration, besides the above mentioneddocuments, the AGIPs long experience in this field: therefore some choices canbe different from, but not in contrast with the quoted standard codes.



1. GENERAL

1.1 Scope

This document has the aim to specify requirements for positioning of fire and gassensing detectors to be installed on AGIP offshore fixed installations.

What described in this specification represents the minimum requirement to befollowed designing platforms for liquid and gaseous hydrocarbons extraction.

The number of sensors stated for each situation described in the documentrepresents a minimum typical value obtained from several previous situationsoccurred during AGIPs experience; the designer shall however verify that thenumber of sensors is in accordance with the provisions at the realization time.



1.2 Normative references

1.21 European normative references

At this moment applicable European Normative References related to thespecification does not exist.

1.2.2 Normative references of ISO, IEC and national organizations

ISO 10418 Recommended Practice for Analysis,Design, Installation and Testing of BasicSurface Safety Systems OffshoreProduction Platforms.

UNI-CNVVF/CPAI-9795

Det Norske Veritas - RPC105

Sistemi fissi automatici di rivelazione e disegnalazione manuale d'incendio

Fire and gas detection.

1.2.3 Normative references of other organizations

NFPA NFC 72E/chapter 3

NFPA NFC 72/E chapter 4

NFPA NFC 72/E Chapter 5

Automatic fire detectors - Heath sensingfire detectors

Automatic fire detectors - Smoke sensingfire detectors

Automatic fire detectors - Flame sensingfire detectors

1.2.4 Legislation

In areas different from Italy the legislation of the involved country shall to beconsidered.

- DPR 24 Maggio 1979 n886 - art.49 -50 -51Integrazione e adeguamento delle norme di polizia delle miniere e delle cave,contenute nel DPR 9 Aprile 1959 n128, al fine di regolare le attivit diprospezione, di ricerca e di coltivazione degli idrocarburi nel mare territoriale enella piattaforma continentale

- Regolamento concernente I criteri generali per la sicurezza antincendio dellepiattaforme fisse e strutture fisse assimilabili (final draft 17/5/1991)

- D.P.R. 27 Aprile 1955 n547Norme per la prevenzione infortuni



2. FUNCTIONAL NORMATIVE REQUIREMENT

2.1 Definitions

The following definitions are applied in this document:

Flammable gas sensors

Devices containing a sensing element fit for flammable gas detection in air (so asto signal the possibility of a potentially explosive mixture formation.

Inlet plenum

A duct immediately before the air inlet of the fan of conditioning plant(downstream the connection of recirculated and supplied air flows).



2.2 Operative environment

Sensors positioning and installing shall be realised according to the environmentalconditions of the installation place defined by the Design specification.

All the environmental factors, that can influence the detection system reliability,shall be to consider:

- minimum and maximum temperature- wind velocity and direction- height as to the sea level- condensation- presence of bodies (sand, dust)- presence of polluting and corrosive substances- possibility of mould growth- earthquakes- mechanical stress and vibrations due to normal running- direct or indirect fulmination- electromagnetic influences- fire and explosion hazard.



2.3 Functional requirements

2.3.1 Heat sensors

2.3.1.1 Positioning general requirements

Heat sensors are installed where probability of fire with a strong heat developmentis greater and where the reliability criteria suggest their use in order to get theplants shutdown; the environmental conditions of platforms suggest the use offusible plug and thermosensitive cable sensors.

Since the most frequent event and most difficult to detect is the jet-fire from acrack of a ring-joint gasket, heat sensors positioning shall be to study carefully inorder that the sensors themselves are placed connected with the possible leakagepoints so as to minimise the alarm times.Referring to a jet-fire type (produced by a methane leakage at 70 bar and 50Cfrom a hole 5 mm in diameter) the calculations show that fusible plug must be notfarthest than 2 m from the possible leakage point so as to, even in the worstconditions, it can operate with a delay not higher than 3 5 minutes.

2.3.1.2 Fusible plug sensors

The installation modalities in the wellhead area, into the process module and in thecombustible liquid storage area shall comply with what hereinafter listed; for allthe other situations it is worth the reference lines of the ISO 10418 codes.

Wellhead area

- Environment:open with natural ventilation

- Sensors positioning:n1 fusible plugs network close to the perimeter placed 50 cm above thewellheads with at least a plug for each welln1 supplementary network, again 50 cm above the wellheads, around the twopossible central wells.

The distance between two consecutive plugs on each row shall be 0.35 m.



The general layout of what above mentioned, for a 12 wellheads area, is shown inAnnex 1.

Wellheads with depth safety valves (DHSV) shall be provided with a network offusible plugs dedicated to this valve shutting.

Process module

- Environment:closed with continuous automatic forced ventilationclosed with ventilation activated by flammable gas sensorsopen with natural ventilation

- Sensors positioning:n1 fusible plugs network, placed above the upper bottom of separators, withplugs upwards and downwards alternatively.n1 plugs network, placed on the manifolds (below the grid pathways), withplugs towards separators and manifold alternativelyn1 plugs network (3 as a minimum) above the blocks panel.

The distance between two consecutive plugs on each row shall be normally equalto 0.35 m.

The general layout of what above mentioned, for a 24 separators process module,is shown in Annex 1 (page 28).

Combustible liquids storage area (gas-oil, methanol)


- Sensors positioning:n2 rows of fusible plugs placed above the vessel so as that, on each row, thefusible plugs are placed connected with the inlet, outlet piping and ventn2 plugs on the pumps of liquid, one for each connection element.

2.3.1.3 Thermosensitive cable sensors

The layout of thermosensitive cable sensors shall be ideally over the fusible plugpositions which could need to fulfil the specific requirement of the same users.



2.3.2 Smoke sensors


Typical bench marks and installation criteria are specified in UNI-CNVVF/CPAI9795 code that considers the room height and the installed ventilating system.

Into the rooms where a dimension prevails among the other, linear optical sensorsshall be to consider instead of point optical sensors; in this event it shall be to referto the NFPA-NFC 72E Chapter 4 code.

Positioning shall be to study since smokes trend to agglomerate during the path tothe sensor.This phenomenon acquires particular relief for ionisation sensors: if theagglomerating smoke particles reach a size over one micron, the sensitivity of thesensors reduces considerably.It is thus necessary that the possible fire is as close as possible to the sensor.

Sensors which belong to a same majority voting logic shall be placed in order toactivate simultaneously, however their mutual distance shall not be above 3 m.

2.3.2.2 Specific requirements for non hazardous areas

Conditioning plant room

- Environment:closed and ventilated

- Sensors positioningn2 smoke sensors: both of them placed along the main room dimensionn1 smoke sensor into the inlet plenum, downstream the filters.

Emergency power generator rooms (UPS)

- Environment:closed with independent forced ventilation

- Sensors positioning:n2 smoke sensors: generally one above the generator and the other oneconnected with the system control board.



Instrumentation air compressor room


- Sensors positioning:n2 smoke sensors: one above each equipment

Control rooms (Electric control room normal operating, electric control roomemergency)

- Environment:closed with forced ventilation

- Sensors positioning:n2 smoke sensors (for each room), placed above the control panels andconnected with the main dimension of the panel itself.n2 smoke sensors (for each room), installed on the false floor

Sensors shall be installed according to a majority logic with the followingprovisions: each channel shall consist of n1 sensor into the room and n1 sensoron the false floor.

Accommodations (main, accommodations and, additional accommodations deck)


- Sensor positioning:n2 smoke sensors, placed along the main room dimension, into each of thefollowing areas: galley, living and cooking roomsn1 smoke sensor into each of the other rooms: platform heads office, waterpower plant room, sick bay, refrigerators rooms (only if engines are into theroom), store room, laundry room, single cabins or accommodations.

2.3.2.3 Specific requirements for hazardous areas

Gas generators canopy

- Environmentclosed with independent forced ventilation- Sensor positioning:

a) positioning into a single room (with equipment facing their own panels)n2 smoke sensors for each equipment: one above each generator and the otherclose to the control panel of the relating group.b) positioning into separated roomsn2 smoke sensors: one above the generator and the other close to the controlpanel of the group.



2.3.3 Flame sensors


Flame sensors can generally detect a fire of 0.9 m 2 wide at a typical distance of 15m, the detection angle is normally equal to 120; positioning shall howeverconsider the characteristics stated by the supplier and shall be realised accordingto the provisions of NFPA-NFC 72E/chapter 5.

Since the electromagnetic waves propagate in straight lines, the presence of solidsbetween fire and sensor can not allow a right operating of this one; so the flamesensors are to be avoided in congested areas unless to provide a simultaneousdetection with other sensors, even of different type, into the shielded areas.

When a majority voting logic is provided, it is necessary the sensors field of visionis covered by the field of vision of the other, at least into the areas where the firehazard is highest. The flame sensor positioning shall be particularly accurate so asto always fulfil this requirement.




- Sensor positioning:n2 flame sensors placed on the opposite walls of the room

Emergency power generator room (UPS)

- Environment:closed with independent forced ventilationopen with natural ventilation

- Sensors positioning:a) enclosed room positioning

n2 flame sensors installed on the opposite walls of the room connectedwith the equipment axis.

b) open room positioning:n2 flame sensors placed at the upper bordering connected with the equipmentaxis.





- Sensor positioning:a) enclosed room positioning

n2 flame sensors installed on the opposite walls of the room in order tocover the two compressor units.

b) open room positioning:n2 flame sensors placed at the upper bordering in order to cover the twocompressor units.

Control rooms (Electric control room normal operating, electric control roomemergency operating and instrumentation control room)


- Sensors positioning:n2 flame sensors installed on the opposite walls of each room along the sidefree from obstacles.


Well heads area (to be evaluated)


- Sensor positioning:n4 flame sensors on opposite sides by the two diagonals of the area connectedwith the upper bordering.

In presence of several well heads what above stated shall be able to assure amonitoring of the whole area.

Process module (to be evaluated)

- Environment:closed with independent forced ventilationclosed with ventilation activated by flammable gas sensorsopen with natural ventilation



- Sensor positioning:n4 flame sensors on opposite sides by the two diagonals of the area connectedwith the upper bordering.

In presence of several well heads what above stated shall be able to assure amonitoring of the whole area.

Gas generators canopy/ies


- Sensor positioning:a) single room positioning

n2 flame sensors installed on the opposite walls of the room connectedwith the equipment axis

b) separated rooms positioningn2 flame sensors installed on the opposite walls of the room connectedwith the equipment axis.

Process gas compressor room


- Sensors positioning:n2 flame sensors for each compressor; sensors shall be installed on theopposite walls of the room generally connected with the equipment axis.

Monitoring of possible gas engines, if separated from the compressors, shall berealised by dedicated flame sensors, for each equipment and installed as abovestated.



2.3.4 Flammable gas sensors


Accumulation of flammable gas is to be continuously monitored where required.

Sensors positioning is to be realised taking into consideration the followingprescriptions:

a) sensors positioning shall be realised according to the density of the gas to bedetected, in particular:

Gas lighter than air (relative density 0.9)- at no more than 30 cm below the area covering- if the ceiling has a top line, at no more than 30 cm below this top line- generally on the vertical of the most probable point of leakage or in a

barycentric position of more points of leakage, if close each others.

Gas heavier than air (relative density 1.1)- at about 50 cm above the lower bordering

Gas with a relative density > 0.9 but < 1.1- both below the area covering and above the lower bordering as previously

stated.

In Annex 2 is showed a typical vertical positioning of sensors relating to therelative density of the flammable gas.

b) sensors shall not be placed where the air velocity reaches values critical for thesensor operation; where it isnt possible, sensors shall be protected by suitableshields or by protection elements

c) sensors shall be placed on the air inlets of the safe rooms when these ones areclose to hazardous areas

d) positioning shall consider flows from possible ventilating systems; sensors shallnot be placed where frames and/or equipment can determine air-pocketswithout exchanges



e) if installed outdoor, sensors shall be of protected type and shall be insta lled inorder to minimize any interference caused by outer environmental factors(humidity, rain, salinity, wind, silicon paints, etc.)

f) sensors which belong to a same majority logic shall be positioned in order tooperate simultaneously; their mutual distance shall not be however higher than3 m.


These areas can be concerned only with flammable gas coming in and thusdetection shall be made both on the outer air inlets and close to the entrances, ifadjoining the hazardous areas.

Here below are listed solutions normally required in compliance with thedescribed necessities.



- Sensors positioning:n1 sensor into the inlet plenum, downstream the air filtersn1 sensor into the room at about 1 m from the entrance

Emergency power generator room (U.P.S.)


- Sensors positioning:a) Enclosed environment

n1 sensor on the air inlet, outdoorn1 sensor into the room at about 1-2 m from the inlet duct

b) Open environmentn2 sensors connected with the generator.





- Sensors positioning:a) Enclosed environment

n1 sensor on the air inlet, outdoorn1 sensor into the room at about 1-2 m from the inlet duct

b) Open environmentn2 sensors connected with each air inlet.

Facilities deck entries, main deck and accommodations entries


- Sensors positioning:n1 sensor for each entry at 1 m from the front door (not on the possible innerdoor)

Supplementary accommodations deck

- Environment:closed with central independent air conditionerpartially open with independent dedicated air conditioner

- Sensors positioning:

a) Total closing supplementary accommodations deckn1 sensor at 1 m from each front door located in the protection frame

b) Partial closing supplementary accommodations deckn1 sensor every 2 accommodations in barycentric position as to the relevantconditioners, if facing; otherwise sensors shall be installed in order that allthe conditioners intakes are monitored.


These areas are concerned with flammable gas there contained and thus sensorsshall be installed in order to detect possible leakage.

In presence of few centres of possible leakage a detection close to these centres isto be preferred; in presence of a large number of centres of possible leakage thedetection of area by a network of point sensors is to be preferred.



When monitoring areas with not more than 3 air exchanges/hour the sensorsmutual distance shall not be above 6 m, in order to assure an adequate reactiontime (about 1 minute), according with a calculation for a typical leakage (methaneleakage at 75 bar from a hole 3.2 mm in diameter).

Infrared linear sensors shall be to consider for the boundary lines monitoring,provided it assures equivalent reliability.

Wellhead area


- Sensors positioning:A sensor network shall be realized and located at a mutual distance of 6 mapproximately; as a rule it shall need not less than:

- n2 sensors into area with 4 wells- n2 sensors into area with 6 wells- n4 sensors into area with 12 wells- n6 sensors into area with 15 wells.

The general layout for sensors location for each situation is showed in Annex 3.

Process module

- Environment:closed with a continuous independent forced ventilationclosed with a ventilation activated by flammable gas sensorsopen with natural ventilation

- Sensor positioning:

a) Enclosed environment with a continuous independent forced ventilationn1 sensor close to the air inlet of each extractor (if the manifold duct is notprovided)n1 sensor close to each inlet duct (if the manifold duct is provided).



b) Enclosed environment with ventilation activated b y flammable gas sensors.

A sensor network shall be preferably realized and located at a mutualdistance of 6 m approximately; as a rule it shall need not less than:

- n4 sensors for modules with 12 separators- n6 sensors for modules with 18 separators- n6 sensors for modules with 24 separators- n8 sensors for modules with 30 separators.

The general layout for sensors location for each situation is showed inAnnex 3 (pages 33-34-35-36).

c) Open environment with natural ventilationIt is valid what stated at point b).



- Sensor positioning:n1 sensor connected with each compressor headn1 supplementary sensor, every three compressors (or portion of three), to beprovided into the space if enclosed.

Monitoring of eventual gas engines, if separated from compressors, shall berealised with one sensor for each equipment.



2.3.5 Toxic gas sensors


Toxic gas detection shall be realised only if the conditions provided by AGIP03380.GPF.SAF.PRG specification can occur; this chapter is thus applicable onlyin these conditions.

Accumulation of toxic gas, generally sulphydric acid H 2S, is to be continuouslymonitored where required.

Sensors positioning is to be realised taking into consideration the followingprescriptions:

a) sensors shall be normally installed at about 0.9 m in height from the lowerbordering (since H2S is heavier than hair tends to accumulate downwards;however when released during the leakage is mixed with natural gas, a mixturelighter than hair can create, at least in a first stage: that can require some sensoreven at the height of the possible leakage)

b) positioning shall consider flows from possible ventilating systems; sensors shallnot be placed where frames and/or equipment can determine air-pocketswithout exchanges

c) if installed outdoor, sensors shall be of protected type and shall be installed inorder to minimize any interference caused by outer environmental factors(humidity, rain, salinity, wind, etc.)


These areas can be concerned only with toxic gas coming in and thus detectionshall be made both on the outer air inlets and close to the entrances, if adjoiningthe hazardous areas.

Here below are listed solutions normally required in compliance with thedescribed necessities.



- Sensors positioning:n1 sensor into the inlet plenum, downstream the air filtersn1 sensor into the room at about 1 m from the entrance



Emergency power generator room (U.P.S.)


- Sensors positioning:n1 sensor on the air inlet, outdoorn1 sensor into the room at about 1-2 m from the inlet duct



- Sensors positioning:n1 sensor on the air inlet, outdoorn1 sensor into the room at about 1-2 m from the inlet duct

Facilities deck entries, main deck and accommodations entries


- Sensors positioning:n1 sensor for each entry at 1 m from the front door (not on the possible innerdoor)

Supplementary accommodations deck

- Environment:closed with central independent air conditionerpartially open with independent dedicated air conditioner

- Sensors positioning:

a) Total closing supplementary accommodations deckn1 sensor at 1 m from each front door located in the protection frame

b) Partial closing supplementary accommodations deckn1 sensor every 2 accommodations in barycentric position as to the relevantconditioners, if facing; otherwise sensors shall be installed in order that allthe conditioners intakes are monitored.




These areas are concerned with toxic gas there contained and thus sensors shall beinstalled in order to detect possible leakage.

In presence of few centres of possible leakage a detection close to these centres isto be preferred; in presence of a large number of centres of possible leakage thedetection of area by a network of point sensors is to be preferred.

Wellhead area


- Sensors positioning:A sensor network shall be realized and located at a mutual distance of 6 mapproximately.

Process module

- Environment:closed with a continuous independent forced ventilationclosed with a ventilation activated by flammable gas sensorsopen with natural ventilation

- Sensor positioning:

a) Enclosed environment with a continuous independent forced ventilationn1 sensor close to the air inlet of each extractor (if the manifold duct is notprovided)n1 sensor close to each inlet duct (if the manifold duct is provided).

b) Enclosed environment with ventilation activated by gas sensors.

A sensor network shall be preferably realized and located at a mutualdistance of 6 m approximately.

c) Open environment with natural ventilationIt is valid what stated at point b).





- Sensor positioning:a) Single canopy

n1 sensor on the air inlet, outdoorn1 sensor into the room.

b) Separated canopiesn1 sensor on the air inlet, outdoorn1 sensor into the room.

Process gas compressor room


- Sensor positioning:n1 sensor connected with each compressor head.



2.4 Ergonomics

According to the operative requirements, sensors shall be placed in order to:

- not hinder passage/escape ways;- be accessible for setting operations- be accessible for maintenance.

2.5 Safety

All the requirement provided by D.P.R. 27/4/1955 n547 shall be to fulfil forsensors positioning.

2.6 Requirements for Quality Management and Quality Assurance

Possible requirements for Quality Management and/or Quality Assurance areincluded in the applicable managerial specification enclosed to the offer request.



3 SUPPLEMENTARY ELEMENTS

3.1 Enclosure and informative annexes

3.1.1 Informative annexes

Annex 1 Typical layout of fusible plugs

Annex 2 Typical elevation of flammable gas sensors

Annex 3 Typical layout of flammable gas sensors




WELL HEAD AREA(12 well heads area)

The general symbol of fusible plug is but, for more clearnessthe symbol above showed has been adopted in this drawing

Well Head

LEGEND

N.B.

Fusible Plug withlateral sensitive side




PROCESS MODULE(24 separators module)

blocks frame

Separator

Fusible Plug withlateral sensitive side

Fusible Plug withupward sensitive side

Fusible Plug withdownward sensitive side

N.B. The general simbol offusible plug isbut, for more clearnessthe simbol above showedhas been adopted inthis drawing



Annex 2 Typical front view of flammable gas sensors

PROCESS MODULE

upperbordering

only for gas withrelative density < 0.9

only for gas withrelative density > 1.1

lowerbordering

Flammable gas sensor

CGD CGD

CGD

CGD

CGD

-

-




WELL HEAD AREA

4 Well Head area

CGDCGD

6 Well Head area

LEGEND

Well Head Flammable gas sensor

CGD CGD

CGD

CGD




WELL HEAD AREA(12 Well Head area)

CGD CGD

CGD CGD

CGD

Flammable gas sensorWell Head

LEGEND




WELL HEAD AREA(15 Well Head area)

CGD CGD

CGD CGD

CGD CGD

LEGEND

Well Head Flammable gas sensor

CGD




PROCESS MODULE(12 Separators module)

LEGEND

Separator Flammable gas sensor

CGD

CGD

CGD

CGD

CGD





CGD

CGD

CGD

CGD

CGD

CGD

LEGEND

Separator Flammable gas sensor

CGD





CGD

Flammable gas sensorSeparator

LEGEND

CGD

CGD

CGD

CGD

CGD

CGD





CGD

CGD

CGD

CGD

CGD

CGD

CGD

CGD

LEGEND

Separator

CGD

Flammable gas sensor

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