koc_e_004_part_3_

KUWAIT OIL COMPANY (K.S.C.)

DOC. NO. KOC-E-004 Pt. 3

KOC RECOMMENDED PRACTICE FOR

SELECTION, INSTALLATION AND MAINTENANCE OF ELECTRICAL EQUIPMENT IN HAZARDOUS AREAS

(ZNTRWSZC SAFETY 7')

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DOC NO. KOC-E-004 Part 3

REV. 1

ISSUING AUTHORITY:

STANDARDS DIVISION

DOC. NO. KOC-E-004 Pt. 3 1 . of 15 REV. 1

KOC RECOMMENDED PRACTICE

FOR

SELECTION, INSTALLATION AND MAINTENANCE OF ELECTRICAL EQUIPMENT IN HAZARDOUS AREAS

INTRINSIC SAFETY ' i f

DOC NO. KOC-E-004 Part 3 Formerly COP-E-00 7 Part 4

I 1&V€W5 -8s KOCSbndard Dr. M. Ups C .

Rev bate Dsrc+lion Ptqpcvad by sseclbbt Td. 61406 -

Td. 61406 Td. 61541

TABLE OF CONTENTS

TITLE


SCOPE

APPLICATION

TERMINOLOGY

REFERENCE CODES AND STANDARDS

ENVIRONMENTAL CONDITIONS

SERVICE CONDITIONS

SELECTION OF SYSTEMIAPPARATUS

SYSTEM'S INSTALLATION REQUIREMENTS

EARTHING OF INTRINSICALLY SAFE SYSTEMS

INSPECTION, TESTING AND MAINTENANCE

QUALITY ASSURANCE

MARKING

DOCUMENTATION

APPENDIX A - INSPECTION SCHEDULE FOR Ex'i'

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PAGE #

REV. 1

1.0 SCOPE


1.1 This part of the Recommended Practice describes the specific requirements for selection, installation and testing of intrinsically safe electrical equipment and systems to be used in hazardous zones.

1.2 It also gives requirements for inspection, maintenance and marking of electrical equipment with the type of protection 'i' (Intrinsic Safety).

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2.0 APPLICATION

REV. 1

2.1 This RP (Recommended Practice) covers those item of equipment identified as Ex 'i' with both categories "ia" and "ib" and it shall be read-in conjunction with Part 1 of this Standard.

2.2 All equipment and installations with the type of protection 'i' shall conform to the requirement of this document, except as modified or supplemented by the project specification or equipment data sheet.

2.3 This document is issued in the following six parts:

Part 1 Recommended Practice for Selection, lnstallation and Maintenance of Electrical Equipment in Hazardous Areas: General Requirements.

Part 2 Recommended Practice for Selection, lnstallation and Maintenance of Electrical Equipment in Hazardous Areas: Flameproof Enclosure 'd' . Part 3 Recommended Practice for Se/ectfonD Ins&l/ation and Maintenance of Electn'cal Equipment in Hazardous Areas: Intnnsic Safety TI.

Part 4 Recommended Practice for Selection, lnstallation and Maintenance of Electrical Equipment in Hazardous Areas: Increased safety 'e'.

Part 5 Recommended Practice for Selection, lnstallation and Maintenance of Electrical Equipment in Hazardous Areas: Non-sparking type 'n' equipment.

Part 6 Recommended Practice for Selection, lnstallation and Maintenance of Electrical Equipment in Hazardous Areas: Oil Immersion '0'. '

3.1 Intrinsic Safetv


A protection technique based upon the restriction of electrical energy within the apparatus and of interconnecting wiring, exposed to a potentially explosive atmosphere, to a level below which can cause ignition by either sparking or heating effects.

3.2 lntrinsicallv Safe Circuits

3.0 TERMINOLOGY

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The circuits in an electrical apparatus are termed as intrinsically safe circuits i f they do not produce spark or thermal effect in the prescribed test conditions (by means of intrinsic safe devices).

3.3 lntrinsicallv Safe Svstem

REV. 1

Assembly of interconnected items of apparatus, which may comprise intrinsically-safe apparatus, associated apparatus and other apparatus, and interconnecting cables in which the circuits within those parts of the system that may be exposed to explosive gas atmospheres are intrinsically-safe circuits.

3.4 Cateqorv 'ia'

Electrical apparatus and systems containing intrinsically-safe circuits that are incapable of causing ignition, with the appropriate safety factors:

when up to two countable faults are applied and, in addition, those non-countable faults which give the most onerous condition.

3.5 Cateqorv 'ib'

Electrical apparatus and systems containing intrinsically-safe circuits which are incapable of causing ignition with the appropriate safety factors:

0 when up to one countable faults is applied and, in addition, '

0 those non-countable faults which produce the most onerous condition.

3.6 Intrinsicallv-Safe A ~ ~ a r a t u S

Electrical apparatus in which all the circuits are intrinsically-safe circuits.

Associated Ap~aratus


Electrical apparatus in which there are both intrinsically-safe circuits and non-intrinsically-safe circuits.

Barrier

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A simple passive or active electronic device consisting of diodes/resistors to limit energy to protect electrical circuits in hazardous areas. This device requires proper grounding.

REV. 1

3.9 Isolators

A complex electronic device to limit energy to protect electrical circats in hazardous areas without the requirement of earthing. This device requires power supply.

REFERENCE CODES AND STANDARDS

4.1 In the event of conflict between this Recommended Practice and the Codes referenced herein, the most stringent requirement shall apply, unless otherwise specified.

4.2 Any exceptions or deviations from this document, along with their merits and justifications, shall be brought to the attention of KOC Controlling Department for their review, consideration and amendment by Standards Division (if required).

4.3 A list of Codes and Standards is given below which are associated with this Recommended Practice. However, the list does not preclude the use of other technical source of information provided that they do not conflict with the listed Standards.

4.4 CODES I STANDARDS .

BS 5345 Part 4

Code of practice for Selection, installation and maintenance of electrical apparatus for use in potentially explosive atmospheres (other than mining applications or explosive processing and manufacture). Electrical apparatus and systems with the type of protection 'i' Intrinsically Safe.

BS 5501 Part 7 EN 50020

Electrical apparatus for potentially explosive atmospheres Intrinsic safety 7'.

BS 5501 Part 9 EN 50039

DOC. NO. KOC-E-004 Pt. 3 1 of 15

Electrical apparatus for potentially explosive atmospheres Specification for intrinsically safe electrical systems 7'.

REV. 1

IEC 79-1 1 .

Electrical apparatus for explosive gas atmospheres Intrinsic safety 7'.

KOC-E-004 PART 1

KOC Recommended Practice for selection, installation and. maintenance of electrical equipment in Hazardous Areas. (General Requirements).

KOC Standard for Hazardous Area Classification.

Standard for Instrument Cables.

ENVIRONMENTAL CONDITIONS

The environment of Kuwait, is severe on all equipment and must be considered carefully before procurement of plant and equipment. It must be assumed that, unless otherwise specified, equipment may be subjected to sand and fine particle dust storms, salt laden winds, thunderstorms, heavy rains, chemical contaminants and extreme temperatures.

Humidity can pose a serious problem with long periods of relative humidity level of 100% being part of the normal weather pattern.

All electrical components shall be designed for continuous operation under ambient temperature of -3OC to + 5 0 ' ~ in the sunshade.

SERVICE CONDITIONS

6.1 All materials used for electrical installation shall be new and in all respects suitable for continuous operation under the environmental conditions.

6.2 Reliability of all equipment to perform continuously in the service conditions specified is essential. Such reliability of all components shall be substantiated by a similar component in operational use elsewhere for a minimum period of 3 years.

http://mykocportal/sites/ts/isg/st/Contents/Standards/Xlinks/Electrical/KOC_E_004_PART_1_.PDF

DOC. NO. KOC-E-004 Pt. 3 1 - of 15 I REV. 1

6.3 All constructional material shall be of high quality and as specified. Prototype or unproven equipment not having well-established record of satisfactory service shall not be considered.

7.0 SELECTION OF SYSTEMIAPPARATUS

All energy storing apparatus employed in a hazardous area must be selected to prevent the energy escaping and be certified as intrinsically safe to the relevant zone, gas group and gas ignition temperature.

All of the components within IS circuit must be certified for use with each other as well as calculations performed regarding cable capacitance, inductance, etc., in order to guarantee the safety of the entire circuit. Simple certification of the individual components shall not be sufficient.

Preference shall be given to use 'IS' isolators which are not dependent on the integrity of the earthing system.

The systemlapparatus must be used within the ambient temperature limits for which it is designed and certified.

Simple apparatus such as thermocouples, resistive sensors, LEDs and switches may be employed in a hazardous area without certification provided that it does not generate or store more than 1.2V, O.1A 20uJ and 25mW.

Simple apparatus having a surface area between 20 mm square and 10 cm square will be classified T4 when the matched output power of the interface device does not exceed:

0 1.3W into 40°C ambient

1.2W into 60°C ambient ) ) due to solar radiation

1 .OW into 80°C ambient )

Equipment identified Ex'ia' is suitable for all Zones including Zone 0 and the equipment identified Ex'ib' is suitable for Zone 1 and 2.

The documentation for the system or self contained intrinsically safe apparatus should indicate the category 'ia' for Zone 0 and 'ia' or 'ib' for other Zones.

The minimum requirements for conductor sizes, junction boxes and terminal units shall be in accordance with BS 5345 Part 4 Clause 14 and 15.

7.10 The wiring of intrinsically safe electrical apparatus shall be of temperature class T I to T4 inclusive. It shall be of copper and in accordance with the requirements of BS 5501 Part 7.

DOC. NO. KOC-E-004 Pt. 3 1 . of 15

7.1 1 The maximum operating temperature of electrical apparatus shall not exceed the minimum ignition temperature of any gas, vapour or mist at intended location.

REV. 1

7.12 For guidance on the'"Hazardous Area Classification", reference shall be made to KOC-G-002 and relevant "HAC" drawings of the facility.

8.0 SYSTEM'S INSTALLATION REQUIREMENTS

For general installation requirements, the Part 1 of this document shall be referred.

It is necessary to ensure that category of any intrinsically safe system or apparatus is suitable for hazardous area. It is also important to ensure that no obvious damage has occurred during installation.

The installation o f any intrinsically safe circuit or system shall comply with the requirements of appropriate certification documents.

Multi-core cables of lntrinsically Safe circuits (IS) shall not be connected to non 'IS' circuits. The Multi-core ,cables junction boxes etc., must be dedicated to Intrinsically Safe circuits of the same level of safety.

The cable parameters for 'IS' circuits shall meet the requirements of KOC-1-011.

The method of cable entry shall preserve the degree of protection of intended location.

The cable shall be supported to its near point of entry to the equipment to prevent any stress on conductor termination.

The terminals for intrinsically safe circuits shall be segregated and identified clearly from terminals of non-intrinsically safe circuits, and separation shall meet the requirements of IEC 79-1 1.

The terminals for external wiring and where connections to plugs and sockets are not prefabricated during manufacture, then it shall comply with IEC 79-1 1 subclause 6.3.1 and 6.3.2.

Where intrinsically safe system or associated apparatus is fitted with more than one plug and socket for either external or internal connections it shall be ensured that interchange of plug is not possible. The mating plugs & sockets shall be identified by marking or colour coding preferably blue.

8.1 1 Cells, batteries and accumulators which require current limiting devices for safety and intended to be used in hazardous zones shall be encapsulated or enclosed with the current limiting devices in such a way that any conductor or terminal, other than output and recharging terminals shall not be accessible.

DOC. NO. KOC-E-004 Pt. 3 1 . Page 1 0 of 1 5

8.12 The installation shall be inspected for compliance with the specifications and requirements of the relevant documentation particularly i f the special installation conditions are described.

REV. 1

9.0 EARTHING OF INTRINSICALLY SAFE SYSTEMS

Where the earthing of enclosures, conductors, metal screens, printed wiring board conductors, segregation contacts of plug-in connectors and diode safety barriers is required to maintain the type of protection, the cross-sectional area of any conductors, connectors and-ierminals shall be capable of carrying rated current.

The minimum cross-sectional area of conductor used for earthing connections should be equivalent to a copper conductor of 4 mm square.

The conductor used for the earth connection should be insulated to prevent interference of earth by fault current which might flow in metallic parts.

The earthing conductor shall be given extra mechanical protection in places where the risk of damage is high.

The impedance between the barrier earth busbar and the point' of connection to the main power system earth shall be maintained less than 1 ohm even if a separate earthing rod has to be used for preserving the integrity of intrinsically safe system (e.g., a diode safety barrier earth, a transformer screen earth, a barrier relay frame earth etc.).

The integrity of earthing system shall not be affected by inadvertent removal of a plug when the earthing connection is made via junction boxes, plugs and, sockets.

Where diode safety barriers are used, care shall be taken t o ensure that barrier device for intrinsically safe system is in accordance with BS 5345 Part 4 Clause 17 and system documentation. A separate 'IS' earthing shall be needed where barriers are in use.

10.0 INSPECTION, TESTING AND MAINTENANCE

10.1 The general recommendations for inspection and testing are given in Part 1 of this document that apply equally to any electrical equipment or installation in hazardous zones. The additional inspection and testing requirements for equipment with the type of protection 'i' are given below:

Any change in area classification or process changes on a plant should be immediately followed by an initial inspection of all affected systems, to ensure that intrinsically safe systems and apparatus remain suitable (Refer to Inspection Schedule Appendix A).


After any repair or modification to a piece of equipment, it shall be inspected to ensure its compliance with the system documentation before it is reinstalled.

Regular inspections shall be carried out by properly trained personnel to minimize the risk of an intrinsically safe system or apparatus acting as a source of ignition due to accidental damage or unauthorized interference.

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Guidqnce for initial and periodic inspections is given in Appendix A. such inspections shall be carried out at least once every two years. More frequent inspections may be justified for installation in particularly arduous environmental conditions.

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REV. 1

A dossier should be retained with all design certification available to which the inspection and tests records are added to. This shall.be held by the maintenance Department responsible for the equipment.

Intrinsically safe equipment, associated apparatus or installation shall be subject to a type test by the manufacturer to ensure that intrinsically safe circuits are incapable of causing ignition under the condition specified for the appropriate category of electrical equipment and the appropriate grouping. The exemptions from this test may be made for the circuits only in accordance with BS 5501 Part 7 Clause 9 = (EN 50020).

Intrinsically safe system or self contained electrical equipment shall be certified and installed in accordance with the requirements of its certificate.

A proper record shall be maintained for all intrinsically safe systems and self contained intrinsically safe electrical equipment showing results of inspections and tests. In addition, all action taken to correct defects during inspections shall be recorded.

Where compliance with the appropriate documentation cannot be demonstrated by physical inspections after installation, electrical testing shall be carried out in accordance with BS 5345 Part 4 Clause 21.

If any self contained intrinsically safe equipment is removed for maintenance, all exposed conductors shall be secured mechanically and electrically. It shall be ensured that maintenance work does not reduce the level of safety achieved by intrinsically safe systems.

10.12 Only certified, relevant and specified test instruments shall be used for maintenance work at hazardous locations. Where certified instruments are not available, the 'Hot Work Permit' system shall be implemented. The site maintenance work shall be restricted to the following:


0 Disconnection, removal or replacement of items of electrical apparatus and cabling.

0 Adjustment of any controls that is necessary for the calibration of the electrical apparatus or system.

Removal and replacement of any "plug-in" components or assemblies.

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Any other maintenance activity specifically permitted by the relevant documentation.

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REV. 1

11 -0 QUALITY ASSURANCE

11.1 The manufacturer shall operate a quality system which ensures that - the requirements of this Standard are achieved. The quality system

shall preferably be based on IS0 9000 series of standards and the manufacturer shall demonstrate compliance by providing a copy of the accredited certificate or the manufacturer's quality manual. Verification of the manufacturer's quality system is normally part of the pre-qualification procedure, and is therefore not detailed in the core text of this Standard.

12.1 Intrinsically safe electrical apparatus and associated components shall carry marking on the main part at a visible place. The marking shall include:

0 The name of the manufacturer or his registered trade mark.

0 The manufacturer's type of identification.

0 The sign for type of protection and category Ex 'ia' or Ex 'ib' or with additional letter 'E'.

The group of electrical apparatus.

0 Maximum surface temperature.

Serial Number.

Certification reference.

0 Installation drawing No.

1 0 The mark X, if applicable.

13.1 The manufacturer shall provide the following information:


a) Electrical parameters for

power sources - .Uo, lo, Po and, if applicable, C,, Lo and the permissible LIR ratio.

13.0 DOCUMENTATION

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power receivers - U,, /,, P,, Ci, L,, and the LIR ratio.

REV. 1

b) Any special requirements for installation and use.

C) The maximum rated voltage, Urn, of non-intrinsically-safe terminals.

d) The maximum possible voltage of the circuitry and the separation voltage of an opto-coupler both, Urn.

e) A completion dossier shall be provided on completion of installation containing the manufacturer's certification for the devices, the designer's circuit diagram and any installation test records. This dossier is to be held by maintenance for reference purposes and addition of inspection reports.

13.2 All correspondence, drawings, instructions, data sheets, design calculations, or any other written information shall be in English language.

13.3 All dimensions, units of measurement, physical constants, etc, shall be in SI units, unless otherwise specified.

APPENDIX A

INSPECTION SCHEDULE FOR Ex 'i'

Legend: D = Detailed, C = Close, V = Visual, = Applicable


* = Init ial * * = Periodic

Check that:

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A. APPARATUS

1.

2.

5. 1 Installation is clearly labelled.

Circuit andlor apparatus documentation is appropriate to area classification.

Apparatus installed is that specified in the documentation - Fixed apparatus only.

3.

4.

6 . 1 There are no unauthorized modifications or visible damage.

Circuit andlor apparatus category and group is correct.

Surface temperature class is correct.

7 .

8.

9.

10.

B. I INSTALLATION

Safety barrier units, other energy limiting devices and field devices are of the approved type, installed in accordance with the certification requirements and securely earthed where required.

Electrical connections are tight.

Printed circuit boards are clean and undamaged.

Type of fuse and rating are appropriate.

11. Type of lamp and rating are appropriate as specified in the documentation.

2. Cable screens are earthed in accordance with the documentation.

1. Cables are installed in accordance with the documentation.

3. There is no obvious damage to cables.

4.

5 .

7 . 1 Earth connections maintain the integrity of the type of protection. I

1

Sealing of trunking, ducts, pipes andlor conduits is satisfactory.

All point-to-point connections are correct and tight.

6. Earth continuity is satisfactory (e.g. connections are tight and conductors are of suffic'ient cross-section and in accordance with clause 8.0.

Separation is maintained between intrinsically safe and non-intrinsically safe circuits.

8.

Grade o f Inspection

The intrinsically safe circuit is isolated from earth or earthed at one point only (refer to documentation).

APPENDIX A Cont..


INSPECTION SCHEDULE FOR Ex 'i'

gend: D = Detailed, C = Close, V = Visual, = Applicable * = Initial * * = Periodic

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Check that:

REV. 1

10. As applicable, short-circuit protection of the power supply is in accordance with the documentation.

11.

Grade of

Special conditions of use (if applicable) are complied with.

1.

2.

Apparatus is adequately protected against corrosion, weather, vibration and other adverse factors

No undue external accumulation of dust and dirt.

Inspection

. +*

D C V

. . e . .

e . .

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koc_e_004_part_3_

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