Abbreviations, Acronyms and Definitions

ABS (American Bureau of Shipping)

ABS establishes and applies technical standards and rules for the design, construction and operational maintenance of ships and other marine structures. Classification is a process that certifies adherence to these rules. www.eagle.org

AEx

Required marking prefix for electrical apparatus for use in hazardous (classified) locations in compliance with applicable and appropriate USA rules, regulations, codes, standards and recommended practices, e.g. as required marking prefix for equipment meeting one or more types of protection in ANSI/ISA-60079-0 and as defined in Article 505 of the NEC®.

ANSI (American National Standards Institute)

www.ansi.org

Area Classification

The purpose of area classification is to provide a basis for the correct selection, installation and location of electrical and non-electrical equipment in those areas. Areas must be classified depending on the properties of the flammable vapours, liquids, gases, mists, dusts or fibres, e.g. ignition characteristics, that may be present and the likelihood that a flammable or combustible concentration is present.

The aim of area classification is to avoid ignition of flammable releases that may occur in the operation of facilities. The intent is to reduce to an acceptable minimum level the probability of a flammable atmosphere and an ignition source occurring simultaneously. Area classification is the division of a facility into three-dimensional hazardous areas (Hazardous (Classified) Locations) and non-hazardous areas (Unclassified Locations) and the subdivision of the hazardous area into 'Zones' or ‘Divisions’.

Hazardous Areas (Hazardous (Classified) Locations) may be sub-divided into Zones or Divisions as follows:-

Zone 0 - An area in which an explosive atmosphere is constantly present, or present for long periods. (Rough Guide: More than 1,000 hours / year).

Zone 1 - An area in which an explosive atmosphere is likely to occur in normal operation. (Rough Guide: 10 hours or more / year but less than 1,000 hours / year).

Zone 2 - An area in which an explosive atmosphere is not likely to occur in normal operation and if it occurs, it will exist only for a short time. (Rough Guide: Less than 10 hours / year).

Zone 20 - Where ignitable concentrations of dust or ignitable fibers or flyings are present continuously or for long periods of time.

Zone 21 - Where ignitable concentrations of dust or ignitable fibers or flyings are likely to exist under normal operating conditions, or frequently, because of repair or maintenance operations of because of leakage, or in which equipment is operated or processes are carried on, of such a nature that equipment breakdown or faulty operations could result in the release of ignitable concentrations of dust or ignitable fibers or flyings and also cause simultaneous failure of electrical equipment in a mode to cause the electrical equipment to become a source of ignition or that is adjacent to a Zone 20 location from which ignitable concentrations of dust or ignitable fibers or flyings could be communicated, unless communication is prevented by adequate positive pressure ventilation from a source of clean air and effective safeguards against ventilation failure are provided.

Zone 22 - In which ignitable concentrations of dust or ignitable fibers or flyings are not likely to occur in normal operation, and if they do occur, will only persist for a short period; or in which dusts or fibers or flyings are handled, processed or used but in which the dusts, fibers or flyings are normally confined within closed containers of closed systems from which they can escape, only as a result of the abnormal operation of the equipment with which the dust, fibers or flyings are handled, processed or used; or that is adjacent to a Zone 21 location, from which ignitable concentrations of dust, fibers or flyings could be communicated, unless such communication is prevented by adequate positive pressure ventilation from a source of clean air and effective safeguards against ventilation failure are provided.

Class I, Division 1 Location - A location (1) in which ignitable concentrations of flammable gases or vapours can exist under normal operating conditions; (2) in which ignitable concentrations of such gases or vapours may exist frequently because of repair or maintenance operations or because of leakage; or (3) in which breakdown or faulty operation of equipment or processes might release ignitable concentrations of flammable gases or vapours and might also cause simultaneous failure of electrical equipment that could act as a source of ignition. (See NEC® Article 500 and API RP 500).

Class I, Division 2 Location - A location (1) in which volatile flammable liquids or flammable gases are handled, processed, or used, but in which the liquids, vapours, or gases will normally be confined within closed containers or closed systems from which they can escape only in case of accidental rupture or breakdown of such containers or systems, or in case of abnormal operation of equipment; (2) in which ignitable concentrations of gases or vapours are normally prevented by positive mechanical ventilation and might become hazardous through failure or abnormal operation of the ventilating equipment; or (3) that is adjacent to a Class I, Division 1 location and to which ignitable concentrations of gases or vapours might occasionally be communicated unless such communication is prevented by adequate positive-pressure ventilation from a source of clean air and effective safeguards against ventilation failure are provided. Electrical conduits and their associated enclosures separated from process fluids by a single seal or barrier are classified as a Class I, Division 2 location if the outside of the conduit and enclosures is a nonhazardous (unclassified) location. (See NEC® Article 500 and API RP 500).

Class II, Division 1 Location - A location (1) in which combustible dust is in the air under normal operating conditions in quantities sufficient to produce explosive or ignitable mixtures; (2) in which mechanical failure or abnormal operation of machinery or equipment might cause such explosive or ignitable mixtures to be produced and might also provide a source of ignition through simultaneous ( the word "simultaneous" is not included in the Canadian definition) failure of electric equipment, operation of protection devices, or from other causes; or (3) in which combustible dusts of an electrically conductive nature may be present in hazardous quantities.

Class II, Division 2 Location - A location in which combustible dust is not normally in the air in quantities sufficient to produce explosive or ignitable mixtures and dust accumulations are normally insufficient to interfere with the normal operation of electrical equipment or other apparatus, but combustible dust may be in suspension in the air as a result of infrequent malfunctioning of handling or processing equipment and where combustible dust accumulations on, in, or in the vicinity of the electrical or may be ignitable by abnormal operation or failure of electrical equipment.

Class III, Division 1 Location - A location in which easily ignitable fibers or materials producing flyings are handled, manufactured or used.

Class III, Division 2 Location - A location in which easily ignitable fibers are stored or handled (except in the process of manufacture).

Typical area classification standards, codes, recommended practices etc. are detailed, for example, in IEC 60079-10-1, Explosive atmospheres –Part 10-1 : Classification of Hazardous Areas – Explosive gas atmospheres, API RP 500 - Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, API RP 505 - Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Zone 0, Zone 1, and Zone 2, The Institute of Petroleum IP15 Code. ANSI/NFPA 497 - Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas.

API (American Petroleum Institute)

www.api.org

Approved

A term used for e.g. devices that are acceptable to the Authority Having Jurisdiction (AHJ).

ASME (American Society of Mechanical Engineers)

www.asme.org

ASTM (Formerly American Society for Testing and Materials)

www.astm.org

ATEX Directive 94/9/EC.

This European Directive provides the technical requirements to be applied to equipment intended for use in potentially explosive atmospheres. The Directive has been mandatory from 1st July 2003. It is named after the French "ATmosphere EXplosible.

The ATEX 137 Directive, 99/92/EC.

This European Directive covers the use of equipment in potentially explosive atmospheres and its aim is to establish minimum requirements for improving the safety and health of workers. The article defines the;

  • Obligations of the employees re. the prevention and protection against explosions.
  • Assessment obligations re. the assessment of explosion risks.
  • General obligations re. the safety and health of worker.
  • Requirements for explosion protection documents.

AHJ (Authority Having Jurisdiction)

Term used, for example by the NEC®, to describe an organization, office, or individual that has the responsibility and authority for approving equipment, installations, or procedures.

Baseefa

A world-renowned certification body principally concerned with electrical and mechanical equipment intended for installation and use in potentially explosive atmospheres. They are accredited by the United Kingdom Accreditation Service (UKAS), and are a Notified Body for the European ATEX Directive and have global acceptance within the IECEx Scheme. Baseefa became part of SGS in 2011. www.baseefa.com

BDV (Blow Down Valve)

An automatically operated valve, fail open and generally controlled from the SIS.

BSEE (Bureau of Safety and Environmental Enforcement

The Bureau of Safety and Environmental Enforcement provides oversight and enforcement to promote safety, protect the environment, and conserve offshore resources in the USA. www.bsee.gov

CE marking

CE marking is a declaration by the manufacturer that the product meets with all the appropriate European Directives. The initials "CE" do not stand for any specific words but are a declaration by the manufacturer that his product meets the requirements of the applicable European Directive(s). e.g. PED.

Certificate

Document that assures the conformity of a product, process, system, person, or organization with specified requirements. The certificate may be either the supplier’s declaration of conformity, or the purchaser’s recognition of conformity or certification (as a result of action by a third party) as defined in ISO/IEC 17000. “Certification” is a conformity assessment by a third party which results in listing or labelling, whereas a “certificate” is prepared by a first, second, or third party.

CEPEL (Centro de Pesquisas de Energia Electrica)

In Brasil, all electrical or electronic equipment for use in potentially explosive atmospheres should be certified by a Brasilian certification body recognised by INMETRO. CEPEL is an accredited body that is able to issue relevant certification. www.cepel.br

CoPC (Certification of Personnel Competence Scheme)

IEC Ex 05A guide sets out information regarding the operation of the CoPC for an individual to obtain an IECEx Certificate of Personnel Competence that is intended to provide the international community that such personnel maintain the ability to provide services in accordance with the CoPC scheme.

CEN (European Committee for Standardisation)

www.cen.eu/cenorm/homepage.htm

CENELEC (European Committee for Electrotechnical Standardization)

www.cenelec.eu

CETOP (Comité Européen des Transmissions Oléohydrauliques et Pneumatiques)

A European Fluid Power Committee. www.cetop.org

Check Valve

A valve that is designed to allow the control media to flow in a given direction but closes to prevent backflow. A Check Valve is similar to but not the same as a “non-return valve”.

Classification Society

A Company that may also enforce requirements for the design and installation of facilities. These requirements, which are in addition to statutory requirements, may influence the design and installation of the electrical and mechanical systems. Classification Societies include ABS, DNV GL and Lloyds Register.

There are numerous regulations, codes, guidelines, and standards for the design, selection, and installation of electrical and mechanical equipment for use Hazardous (Classified) Locations. These requirements are in addition to the requirements for installations in non-hazardous areas (Unclassified Locations).

Control Valve

A valve which regulates the flow or pressure of the control media. Control valves are normally fitted with a valve actuator with or without a valve positioner.

CSA (Canadian Standards Association)

Services offered include testing and certification services to US and Canadian Standards, as well as International certification through agreements with other International authorities. www.csa.ca

CU TR (Customs Union Technical Regulations)

In accordance with the unification of certification requirements for member countries of the Customs Union (Russia, Belarus and Kazakhstan), new Customs Union Technical Regulations for machinery and equipment came into force on February 15th, 2013, with a 2 year period to allow for adjustment. These new technical regulations replace the previous ‘GOST’ certificate and RTN permit system, which will no longer be valid from February 15th 2015 in the scope of the new regulations;

  • Safety of machinery and equipment
  • Safety of equipment used in the explosive atmosphere
  • Safety of devices working on gas fuel
  • Safety of low voltage equipment
  • EMC of technical devices
  • Safety of lifts

They will replace national requirements and conformity assessment procedures of each member state of the Customs Union (GOST – R for Russia, GOST – K for Kazakhstan). New conformity documents and new Mark of Conformity for Customs Union will be applicable (see EAC).

Cv

The flow coefficient, Cv, has several classifications such as the volume (in US gallons) of water, at 60º F that will flow per minute through a valve with a pressure drop of 1 psi across the valve. One flow measurement classification is defined by International Standard ISO 6358. “Determination of flow-rate characteristics of pneumatic fluid power components”. This standard specifies a method for testing pneumatic fluidpower components which use compressible fluids, i.e. gases, to enable their flow-rate characteristics to be compared. The flow coefficient Kv is defined as the flow of water in cubic metres per hour, or litres per minute, at 20º C, with a pressure drop of 1 Bar.

Cv = Q SG/dp 

Where:

  • Cv = flow coefficient of the valve
  • Q = flow rate in US gallons
  • Δp = pressure drop across the valve lb/in²
  • SG = specific gravity of fluid (water = 1)
  • Cv = 1.17 Kv

DCS (Distributed Control System)

Is a control system that, for example, controls manufacturing processes and monitors and controls distributed equipment.

DCV (Directional Control Valve)

A valve designed to direct the control media, at the appropriate time, to the point in a system where it will do work.

Diaphragm Valve

A bi-directional valve which is operated by applying a force to a flexible component.

DNV GL (Det Norske Veritas - Germanischer Lloyd)

DNV GL is one on the world’s leading ship and offshore classification societies, leading technical advisor to the global oil and gas industry and a leading expert for the energy value chain including renewables and energy efficiency. They are also a certification body. www.dnvgl.com

DBB (Double Block and Bleed)

A valve in which positive shut-off is achieved at both the inlet and outlet sides. A small port is fitted to discharge the control media. This port can help an operator check if the valve is leaking. Two isolation valves in series with a vent valve between them.

DPR (Drill Pipe Riser)

DSEAR (Dangerous Substances and Explosive Atmospheres Regulations)

In the UK from July 2006, employers must have completed the risk assessment, classification and documentation of their workplace and personnel. This also includes training and procedures, where potentially explosive atmospheres or dangerous substances may occur. www.hse.gov.uk/fireandexplosion/dsear.htm

EAC (EurAsian Conformity)

when marked on equipment represents the conformity with the technical requirements of the ‘Customs Union’ (Russia, Kazakhstan and Belarus). This replaces the GOST symbol and associated regulations. (see CU TR).

EEx

A marking prefix for equipment complying with one or more types of explosion protection techniques in accordance with ATEX. New equipment approvals only include Ex and not EEx.

EMC (Electro-Magnetic Compatibility)

EMI (Electro Magnetic Interference)

Encapsulation, Ex m

A type of protection in which the parts that could ignite a potentially explosive atmosphere by either sparking or heating are enclosed in an encapsulant in such a way that the potentially explosive atmosphere cannot be ignited. Permitted for use in Zones 1 & 2. Applicable standards include IEC 60079-18 ‘ma’, ‘mb’ or ‘mc’.

EPL (Equipment Protection Level)

The EPL may appear in the product marking or documentation. EPLs are designated as G for gas, D for dust, or M for mining and are then followed by a letter (a, b, or c) to give the user a better understanding as to whether the equipment provides either (a) a “very high,” (b) a “high,” or (c) an “enhanced” level of protection against ignition of an explosive atmosphere.

Relationship between EPLs and Zones. According to IEC 60079-14, where only the Zones are identified in the area classification documentation, then the relationship between EPL's and Zones from table below should be followed.

Zone - Equipment Protection Levels (EPLs)

0 - Ga’

1 - Ga’ or ‘Gb’

2 - Ga’, ‘Gb’ or ‘Gc’

Where the EPLs are identified in the area classification documentation, those requirements for selection of the equipment should be followed.

Selection of equipment according to EPLs

The recognised types of protection according to IEC standards have been allocated EPLs according to table below.

“Ga”

  • Intrinsically safe ‘ia’ IEC 60079-11
  • Encapsulation ‘ma’ IEC 60079-18
  • Two independent types of protection each meeting EPL ’Gb’ IEC 60079-26
  • Protection of equipment and transmission systems using optical radiation IEC 60079-28

“Gb”

  • Flameproof enclosures ‘d’ IEC 60079-1
  • Increased safety ‘e’ IEC 60079-7
  • Intrinsically safe ‘ib’ IEC 60079-11
  • Encapsulation ‘m’ ‘mb’ IEC 60079-18
  • Oil immersion ‘o’ IEC 60079-6
  • Pressurized enclosures ‘p’, ’px’ or ‘py’ IEC 60079-2
  • Powder filling ‘q’ IEC 60079-5
  • Fieldbus intrinsically safe concept (FISCO) IEC 60079-27
  • Protection of equipment and transmission systems using optical radiation IEC 60079-28

“Gc”

  • Intrinsically safe ‘ic’ IEC 60079-11
  • Encapsulation ‘mc’ IEC 60079-18
  • Non-sparking ‘n’ or ‘nA’ IEC 60079-15
  • Restricted breathing ‘nR’ IEC 60079-15
  • Energy limitation ‘nL’ IEC 60079-15
  • Sparking equipment ‘nC’ IEC 60079-15
  • Pressurized enclosures ‘pz’ IEC 60079-2
  • Fieldbus non-incendive concept (FNICO) IEC 60079-27

 

For hazardous location equipment, atmospheric conditions are generally considered to be;

 

  • a) an ambient temperature range of -20 °C (-4 °F) to 40 or 60 °C (140 °F) for zones and to -25 °C (-13 °F) to +40 °C (104 °F) for divisions.
  • b) air with normal oxygen content, typically 21 percent by volume; and
  • c) a pressure of 80 kPa (11.6 psia) to 110 kPa (16 psia).

NOTE Equipment specified for atmospheric conditions beyond the above is generally permitted but may be subjected to additional requirements.

Equipment Marking

Typical ATEX marking requirements;

  • The name and address of the manufacturer
  • Type, serial number and the year in which the equipment was constructed
  • The specific marking of explosion protection followed by the symbol of the equipment group and the category

 

For equipment Group II : - the letter "G" where explosive atmospheres caused by gases, vapour or mists are concerned and / or the letter "D" where explosive atmospheres caused by dusts are concerned

Example:

Bifold Fluidpower, England, OL9 9XA, 0303-0098, Ex d IIC T 85ºC Tamb -60 to +40ºC II 2 GD BAS 02 ATEX 2048

  • Additional CE Marking

 

The CE conformity marking must consist of the initials and be followed by the identification number of the notified body responsible for production control. Example: CE 1180.

ESD (Emergency Shutdown)

A system or stations which, when actuated, initiate facility shutdown.

ESDV (Emergency Shut-Down Valve)

A high integrity shut down valve is generally fail closed and controlled from the SIS and/or HIPPS.

Explosionproof Enclosure

An enclosure that is capable of withstanding an explosion of a gas or vapour within it and of preventing the ignition of an explosive gas or vapour that may surround it and that operates at such an external temperature that a surrounding explosive gas or vapour will not be ignited thereby. This type of enclosure is similar to a flameproof enclosure but the flamepath lengths, gaps, explosion pressures, testing and appropriate testing and standards are different as are the wiring/conduit./cable connection requirements. One applicable USA Certification Document for Class 1, Division 1 is UL 1203. Permitted for use in Class 1, Division 1 & 2. See also NEMA 7 definition.

Explosive Atmosphere

Mixture with air, under atmospheric conditions, of flammable substances in the form of gas, vapour, dust, fibres or flyings which, after ignition, permits self-sustaining propagation. (See Hazardous Area).

FAT (Factory Acceptance Test)

Fire Safe

See API 607, API 6FA, and ISO 10497 for details of valve fire testing requirements.

Flameproof Enclosure, Ex d

A type of protection of electrical apparatus in which the enclosure will withstand an internal explosion of a flammable mixture which has penetrated into the interior, without suffering damage and without causing ignition, through any joints or structural openings in the enclosure, of an external explosive atmosphere consisting of one or more of gases or vapours for which it is designed. Permitted for use in Zones 1 & 2. Applicable standards include IEC 60079-1.

FLNG (Floating Liquefied Natural Gas)

The purpose of a FLNG floating processing facility is to receive, treat and liquefy natural gas from offshore subsea gas fields.

Flow Control Valve

This valve type is used to restrict and maintain a constant pre-determined flow of media in a system. Bifold types are available both uni-directional and bi-directional.

Flow Rate

Flow rate comparisons are not straightforward and care should be taken to ensure equivalence when making comparisons.

  • Kv – Flow rate in m/h of water.
  • Cv – Flow co-efficient (ISO, American, and Japanese standards).

Fluid Contamination Tolerance

Bifold Fluidpower valve types have successfully used several material combinations where specified fluid cleanliness levels have been maintained. Although poppet/seated valves are vulnerable to particle damage in 'dirty' systems, Bifold Fluidpower poppet valves types have demonstrated a degree of tolerance. A further feature of all Bifold Fluidpower pilot stage poppet/seated valves is the inclusion of a 40 micron filter disc for 'last chance' protection against any large particles. Depending on the Bifold Fluidpower valve type, e.g. Slide valves, some types have been qualified using test fluid with a cleanliness standard equal to or worse than NAS 1638, Class 12. Refer to Aerospace Standard SAE AS 4059.

FMEA (Failure Modes and Effects Analysis)

A systematic way to identify and evaluate the effects of different component feature modes, to determine what could eliminate or reduce the chance of failure, and to document the system in consideration.

FMEDA (Failure Modes, Effects, and Diagnostic Analysis)

This is an extension of FMEA, and one of the steps to be taken to achieve functional safety certification per IEC 61508. From the FMEDA, failure rates and Safe Failure Fraction (SFF) are determined.

FPSO (Floating Production Storage Offloading)

FPU (Floating Production Unit)

Fugitive Emissions

EN IS0 15858 defines measurement, test and qualification requirements re the emission (leakage into the environment) from process equipment and valves.

Galvanic Isolation

An arrangement within an item of intrinsically safe apparatus or associated apparatus which permits the transfer of signals or power between two circuits without any direct electrical connection between the two.

Group

The grouping of gases, vapours and dusts are classified into Group I, Group II and Group III categories.

Group I

Is relevant to Hazardous Areas containing firedamp (a mixture of gases, composed mostly of methane, found underground in mines).

Group II

Is intended for use in all other places with Hazardous Areas containing gases. Group II equipment with types of protection ’d’ and 'i' are further subdivided into apparatus group IIA, IIB, or IIC.

Group III

Is relevant to Hazardous Areas with an explosive dust atmosphere

In the USA, the NEC® and other relevant and appropriate documents, refers to the classification of flammable materials of similar hazard. These are defined as follows;

Group A

Atmospheres that do or may contain Acetylene.

Group B

Atmospheres containing Butadiene, ethylene oxide, propylene oxide, acrolein, or hydrogen (or gases or vapours of equivalent hazard to hydrogen, such as manufactured gas. (See NFPA 497).

Group C

Atmospheres containing Cyclopropane, ethyl ether, ethylene, hydrogen sulfide, or gases or vapours of equivalent hazard. (See NFPA 497).

Group D

Atmospheres such as acetone, alcohol, ammonia, benzine, benzol, butane, gasoline, hexane, lacquer solvent vapors, methane, naphtha, natural gas, propane, or gases or vapours of equivalent hazard. (See NFPA 497).

Group E

Atmospheres containing combustible metal dusts regardless of resistivity or other combustible dusts of similarly hazardous characteristics having resistivity of less than 102 ohm-centimeter (magnesium, aluminum, bronze powder, etc.).

Group F

Atmospheres containing carbon black, charcoal, coal, coke dusts that have more than 8% total volatile material ( coal and coke dusts per ASTM 3175-82) or atmospheres containing these dusts sensitized by other materials so that they present an explosion hazard and having resistivity greater than 102 ohm-centimeter but equal to or less than 108 ohm-centimeter.

Group G

Atmospheres containing combustible dusts (flour, starch, pulverized sugar and cocoa, dairy powders, dried hay, etc.) having resistivity of less than 108 ohm-centimeter or greater.

GOST

Is a conformity mark that declares that products bound for Russia are tested and certified in accordance with Russian standards. GOST mark is mandatory for a wide range of products. (see CU TR).

Hazardous Area

This term is also known by different terms such as hazardous (classified) locations, potentially explosive atmospheres, Ex areas and the like and relate to areas where flammable liquids, vapours, gases, dusts, fibres and flyings are likely to occur in quantities sufficient to cause a fire or explosion and as such require special precautions for the construction, installation and use of equipment. (See Explosive atmosphere).

HAZOP (Hazard & Operability studies)

HIPPS (High Integrity Pressure Protection System)

A type of (SIS) designed to prevent over-pressurisation of a plant, such as a chemical plant or oil refinery. The HIPPS will shut-off the source of the high pressure before the design pressure of the system is exceeded, thus preventing loss of containment through rupture (explosion) of a line or vessel. Therefore, the HIPPS is considered as a barrier between a high-pressure and a low-pressure section of an installation.

HPU (Hydraulic Power Unit)

Used to generate, store and supply hydraulic pressure oil and/or water based fluids.

IEC (International Electrotechnical Commission)

The IEC is a global organization that prepares and publishes international standards for all electrical, electronic and related technologies. www.iec.ch

IECEx

The objective of the IECEx Scheme is to facilitate international trade in equipment and services for use in explosive atmospheres, while maintaining the required level of safety. www.iecex.com

IECEx Conformity Mark

The IECEx Conformity Mark shall only be placed on products, packaging materials and promotional materials that are covered by a valid IECEx certificate of conformity listed in the schedule listed on the IECEx certificate. www.iecex.com

Ignition Temperature / Auto Ignition Temperature

The lowest temperature (of a hot surface), at which under specified test conditions, an ignition of a flammable gas or vapour in mixture with air or air/inert gas occurs.

Increased Safety, Ex e

A type of protection applied to electrical apparatus that does not produce arcs or sparks in normal service and under specified abnormal conditions, in which additional measures are applied so as to give increased security against the possibility of excessive temperatures and of the occurrence of arcs and sparks. Permitted for use in Zones 1 & 2. Applicable standards include IEC 60079-7.

Installation Standards, Codes, and Recommended Practices

There are numerous different regulations, codes, recommended practices, guidelines and standards for the design, installation and maintenance of electrical and non-electrical systems for use in Hazardous Areas. The type of operational facility, geographic location, operator practice, local and national legislation authority, having jurisdiction etc. will determine many of the design and installation rules permitted. Bifold has Installation, Operation and Maintenance instructions (IOMs) for their range of products. For further information on the design, selection, installation, inspection, and maintenance of equipment for use in hazardous and non-hazardous areas see, for example;

  • IEC 60079-14 - Explosive atmosheres - Part 14 : Electrical installations design, selection and erection.
  • IEC 60079-17 - Explosive atmosheres - Part 17 : Electrical installations inspection and maintenance.
  • IEC 60079-19 - Explosion atmosheres - Part 19 : Equipment repair, overhaul and reclamation.
  • IEC 60364-6 - Low-voltage electrical installations
  • IEC 61892-7 - Mobile and Fixed offshore Units – Electrical installation, Part 7: Hazardous Areas.
  • ANSI/NFPA 70 - National Electrical Code, NEC®.
  • NFPA 70B - Recommended Practice for Electrical Equipment & Maintenance.
  • API RP 14F - Recommended Practice for Design, Installation and Maintenance of Electrical Systems for Fixed and Floating Offshore Petroleum Facilities for Unclassified and Class I, Division 1 and Division 2 Locations.
  • API RP 14FZ – Recommended Practice for Design, Installation, and Maintenance of Electrical Systems for Fixed and Floating Offshore Petroleum Facilities for Unclassified and Class I, Zone 0, Zone 1 and Zone 2 Locations.

IMO (International Maritime Organisation)

www.imo.org

INMETRO (Instituto Nacional de Metrologia, Normalizacão Qualidade Industrial)

The National Institute of Metrology, Standardization and Industrial Quality (INMETRO) is the National accreditation body for Brasil. Under the Brasilian safety system, product certification is required for hazardous location equipment and many other types of equipment. INMETRO requires a certification organization to review technical documentation and products provided by manufacturers to verify that products comply with Brasilian technical and safety requirements. Products meeting Brasilian product standards and other technical requirements must carry the mandatory INMETRO Mark, as well as the mark of the certification organization, such as CEPEL and UL.

Inspections

Before plant or equipment is brought into service, it shall be given an initial inspection. To ensure that the installations are maintained in a satisfactory condition for continous use within a hazardous area, either

  • a) regular periodic inspections, or
  • b) continuous supervision by skilled personnel and where necessary, maintenance shall be carried out. For example, see IEC 60079-17, NPFA 70B.

Intrinsic Safety, Ex i

A device, instrument or component that will not produce any spark or thermal effects under any conditions that are normal or abnormal that will ignite a specified gas mixture. Electrical and thermal energy limits are at levels incapable of causing ignition. It is common practice to use external barriers with intrinsically safe installations. Because of the method by which intrinsic safety is achieved, it is necessary to ensure that not only the electrical equipment exposed to the explosive atmosphere but also other electrical equipment with which it is interconnected is suitably constructed. There are three levels of protection ‘Ex ia’, ‘Ex ib’ or ‘Ex ic’. Ex ia is permitted for use in Zones 0, 1, & 2. Applicable standards include IEC 60079-11.

Intrinsic Safety Barrier

A component containing a network designed to limit the energy (voltage and current) available to the protected circuit in the hazardous (classified) location under specified fault conditions.

Intrinsic Safety Parameters

Maximum external inductance to resistance ratio (Lo/Ro) ratio of inductance (Lo) to resistance (Ro) of any external circuit connected to the connection facilities of the electrical equipment without invalidating intrinsic safety.

IP (Ingress Protection)

A system of rating standard levels of Ingress Protection provided by the equipment. Reference can be made to IEC/EN 60529.IEC/EN 60529 outlines an international classification system for the sealing effectiveness of enclosures of electrical equipment against the intrusion into the equipment of foreign bodies i.e. tools, dust, fingers and moisture. This classification system utilizes the letters "IP" ("Ingress Protection") followed by two or three digits. A third digit is sometimes used. IP 6X for example indicates the unit is Dust tight. IPX6 for example indicates the unit is protected against heavy seas, or powerful jets of water as found on ships decks. It should be noted that equipment complying with IPX7, Protection against immersion of 1m for 30 minutes, or IPX8, Protection against continuous submersion in water with the time and depth as agreed by the user and manufacturer, will not necessarily comply with IP66.

Degrees of Protection - First Digit

The first digit of the IP code indicates the degree that persons are protected against contact with moving parts (other than smooth rotating shafts, etc) and the degree that equipment is protected against solid foreign bodies intruding into an enclosure.

Degrees of Protection - Second Digit

The second digit indicates the degree of protection of the equipment inside the enclosure against the harmful entry of various forms of moisture (e.g. dripping, spraying, submersion, etc.)

Examples of Degrees of Protection;

  • IP54 - Dust protected, prevents ingress of dust sufficient to cause harm or safe operation of equipment inside an enclosure. Protected from water splashing from any direction.
  • IP66 - Dust tight, no dust ingress. Protected from heavy seas and powerful jets of water.
  • IP67 - Dust tight, no dust ingress. Protected against immersion of up to 1m for 30 minutes. Compliance with IP67 does not necessarily mean compliance with IP66.
  • IP68 - Dust tight, no dust ingress. Protected against submersion under specific time and depth/conditions as agreed between the manufacturer and the user. Compliance with IP67 does not necessarily mean compliance with IP66.

 

See also NEMA definition re ingress protection.

ISA (The Instrumentation, Systems, and Automation Society)

www.isa.org

ISO (International Organization for Standardization)

www.iso.org/iso/en/ISOOnline.frontpage

IWOCS (Installation Workover Control System)

The IWOCS controls and monitors the deployment, operation, and the retrieval of subsea production equipment.

(LEL (Lower Explosive Limit)

Concentration of flammable gas, vapour or mist in air below which an explosive gas atmosphere will not be formed.

LOPA (Layers Of Protection Analysis)

Bifold definitions for pneumatic solenoid valve operators are as follows;

Manual override (M)

The solenoid valve switches on and off with the electrical supply. The manual override button can be pressed to operate the valve when the solenoid is in the electrically de-energised position. The manual override is non-detented, i.e. does not latch in position. When the button is released, the valve spring returns.

Manual reset (ML)

Apply the electrical signal and press the reset button. The valve moves to the energised position and will not deenergise until the electrical supply is removed. The manual reset button also acts as a manual override, when the valve is in the de-energised position and the electrical supply is off. The Manual reset is non-detented, spring return, i.e. does not latch in position.

Tamperproof manual reset (MLT)

Apply electrical signal and press the reset button. The valve moves to the energised position and will not de-energise until electrical power is removed. The valve cannot be moved to the energised position by pressing the button if there is no electrical supply to the solenoid.

 

Bifold definitions for hydraulic solenoid valve operators are as follows;

Manual override (M)

The solenoid valve switches on and off with the electrical supply. The manual override button can be pressed to operate the valve when the solenoid is in the electrically de-energised position. The manual override is non-detented, i.e. does not latch in position. When the button is released, the valve spring returns.

Manual reset (ML)

Apply the electrical signal and press the reset button. The valve moves to the energised position and will not deenergise until the electrical supply is removed. The Manual reset is non-detented, spring return, i.e. does not latch in position.

Manual Override (MOR)

The solenoid valve switches on and off with the electrical supply. The manual override button is rotated through ¾ turn to operate the valve when the solenoid is in the electrically de-energised position. The Manual Override is detented i.e. remains in position until rotated back to its original position when the valve spring returns.

MESG (Maximum Experimental Safe Gap)

The maximum clearance between two parallel metal surfaces that has been found, under specified test conditions, to prevent an explosion in a test chamber from being propagated to a secondary chamber containing the same gas or vapor at the same concentration.

MIC (Minimum Igniting Current)

The ratio of the minimum current required from an inductive spark discharge to ignite the most easily ignitable mixture of a gas or vapor, divided by the minimum current required from an inductive spark discharge to ignite methane under the same test conditions.

MODU (Mobile Offshore Drilling Unit)

MTBF (Mean Time Between Failure)

NACE (formerly National Association of Corrosion Engineers)

NACE MR 01 75 / ISO 15156 standard states requirements so as to prevent the affects of e.g. material cracking, corrosion etc. that may be caused by the presence of hydrogen sulphide (H₂s) in oil and gas environments (sour service). www.nace.org/nace/index.asp

NEC® (National Electrical Code ®)

ANSI/NFPA 70. Refer to Sections 500 through 505 for information on hazardous (classified) locations. Link

Needle Valve

A valve that has a needle-shaped closing component. Often used on secondary systems for delicate control and shut off.

NEMA (National Electrical Manufacturers Association)

The NEMA Standards Publication 250-1997, "Enclosures for Electrical Equipment (1000 Volts Maximum)" refers to specific enclosure types, their applications, and the environmental conditions they are designed to protect against when installed correctly. Two typical NEMA ratings are as follows;

NEMA Type 4

Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against incidental contact with the enclosed equipment; to provide a degree of protection against falling dirt, rain, sleet, snow, windblown dust, splashing water, and hose-directed water; and that will be undamaged by the external formation of ice on the enclosure.

NEMA Type 4X

Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against incidental contact with the enclosed equipment; to provide a degree of protection against falling dirt, rain, sleet, snow, windblown dust, splashing water, hose-directed water, and corrosion; and that will be undamaged by the external formation of ice on the enclosure.

NEMA 7

In Hazardous (Classified) Locations, when completely and properly installed and maintained, Type 7 enclosures are designed to contain an internal explosion without causing an external hazard. NEMA 7 enclosures are not necessarily suitable for outdoor use. See also explosionproof definition. www.nema.org

See also IP (Ingress Protection definition).

NFPA (National Fire Protection Association)

www.nfpa.org

Non-electrical equipment (mechanical) for use in explosive atmospheres.

See IEC 80079-36 and IEC 800079-37. The IEC 60079 series standards/equipment may be supplemented or modified by the IEC 80079-36 and IEC 800079-37 standards depending on the specific type of explosion protection technique(s) applicable. Non electrical type of protection constructional safety “Ex ch”, control of ignition source “Ex bh”, liquid immersion “Ex kh”.

NRTL (Nationally Recognized Testing Laboratory)

OREDA® (Offshore REliability Data)

OSHA (Occupational Safety and Health Administration)

www.osha.gov

OS & Y (Outside Screw and Yoke)

PFD (Probability of Failure on Demand)

PLC (Programmable Logic Controller)

PMI (Positive Material Identification)

PMI testing is intended to identify alloy materials and not to establish the exact conformance of a material to a particular alloy specification. Customer must advise on PMI test procedure. The test procedure should cover the technique used, equipment calibration, qualification requirements of PMI test personnel, testing methodology and documentation requirements.

Poppet/Seated Valves

Balanced poppet valves are one of the simplest types of directional control valve. By design, the valve breaking and making seat contacts means that the valve is susceptible to seated leakage if the hydraulic system fluid has particle contamination. These particles can either become trapped between the stem and seat or embedded in either surface creating a fluid leakage path.

PED (Pressure Equipment Directive)

The 97/23/EC Directive applies to the design, manufacture and conformity assessment of pressure equipment and assemblies with a maximum allowable pressure greater than 0.5 bar above atmospheric pressure. For a safety device, it is the maximum set pressure for which the devise is designed.

PRV (Pressure Relief Valve)

A self-operating valve used to reduce any excess pressure in a system. The valve opens if the internal pressure exceeds that holding the valve disc onto the seat.

PST (Partial Stroke Test)

PST is a technique used in a control system to allow users to test a percentage of the possible failure modes of a shut down valve without the need to physically close the valve fully. PST is used to assist in determining that the safety function will operate on demand.

QEV (Quick Exhaust Valve)

A valve used to provide quick response for high speed applications, for example, when required to dump gas from a pressurized actuator at a high volume in order to stroke the control valve rapidly.

Qualification of Personnel

The inspection and maintenance of installations should be carried out only by experienced personnel, whose training has included instruction on the various types of protection and installation practices, the requirements of the relevant national regulations/company rules applicable to the installation and on the general principles of area classification. Appropriate continuing education or training should be undertaken by personnel on a regular basis.

Regulating Valve

A valve used to regulate and provide a constant pressure output.

SCADA (Supervisory Control and Data Acquisition)

The control and status monitoring of, for example, a production platform process facilities and utility systems may be performed by a SCADA system.

SCM (Subsea Control Module)

In a piloted-hydraulic, electro hydraulic or electrical control system, the SCM unit, upon command, for example from a master control station, directs hydraulic fluid to operate subsea valves.

SCSSV (Surface-Controlled Subsurface Safety Valve)

Device controlled from the surface by hydraulic, electrical, mechanical or other means.

SDV (Shut Down Valve)

A high integrity shutdown valve is generally fail closed and controlled via the SIS.

SSCSV (Subsurface-Controlled Subsurface Safety Valve)

Actuated by the characteristics of the well itself.

SSSV (Subsurface Safety Valve)

A device that prevents uncontrolled well flow when closed.

SSV (Surface Safety Valve)

Automatic wellhead valve assembly which closes upon loss of power supply.

SFF (Safety Failure Fraction)

Shear Plane Valve

These Bifold valve types utilise a metal to metal sealing principle. Fluid porting discs are pressure loaded onto the flat face of a central slide. The slide is moved between the static discs; discs are located on opposing faces of the slide to balance the forces and avoid side loading. Fluid flow port to port is communicated through the porting discs and oilways through the slide. This type of valve has been applied in control pods subsea for many years. It is regarded as being highly reliable because it has no elastomeric dynamic seals and sealing is effected between the metal surfaces moving in shear.

SIF (Safety Instrumented Function)

SIL (Safety Integrity Level)

A determination of a risk of a system in accordance with a recognised standard, e.g., IEC 61508, Functional Safety of Electrical/Electronic/Programmable Electronic Safety-Related Systems, Parts 1-7. A SIL is a statistical representation of the reliability of the SIS when a process demand occurs. There are up to three categories: SILs 1, 2, 3, and 4. The higher the SIL is, the more reliable or effective the system is. SILs are correlated to the Probability of Failure on Demand (PFD), which is equivalent to the unavailability of a system at the time of a process demand.

SIS (Safety Instrumented Systems)

Used to provide safe control functions for processes, e.g. emergency shutdown (ESD), functions. See IEC 61511 for guidance and recommendations.

Skilled Personnel

Persons whose training has included instruction on the various types of protection and installation practices, the requirements of which depend upon, for example, the relevant national regulations/company rules applicable to the installation and on the general principles of area classification.

Slide Valve

A Bifold Fluidpower valve type in which the operating principle is defined follows; a cylindrical slide, having radially drilled apertures through to a central bore, is moved linearly to create flow paths between valve body ports. Dynamic sealing is effected by seals located in the valve body, which are pressure balanced as the apertures pass through them. This operating principle has proved to be extremely tolerant to contaminants. The success of this principle arises from the use of wiping action dynamic seals and the fact that there are no break-make sealing elements which could entrap particles with resultant leakage. A design feature of this type of valve is the elimination of continuous leakage as found in conventional lapped-face spool valves.

Solenoid Valve

A valve operated by an electrical solenoid. Often used, for example, to pilot larger valves, i.e., fitted to valve actuators which in turn control larger valves.

SOV (Solenoid Operated Valve)

Technical person with executive function. Person providing technical management of the skilled personnel, having adequate knowledge in the field of explosion protection, having familiarity with the local conditions, having familiarity with the installation and who has overall responsibility and control of the inspection systems for the electrical equipment within hazardous areas.

TUTU (Topside Umbilical Termination Unit)

Type of Protection

Specific measures applied to electrical and/or mechanical equipment to avoid ignition of a surrounding potentially explosive atmosphere. There are several Types of Protection, i.e. construction techniques, available for electrical and mechanical apparatus for use in Hazardous Areas. The Type of Protection permitted will depend upon the applicable installation codes and rules to be adopted.

The selection of equipment should be in accordance with the following;

  • Classification of the Hazardous Area, e.g. Zone classification.
  • Temperature class, e.g. “T” rating, or ignition temperature of the gas, liquid, vapour's, mist, dust or fibre
  • Where applicable, the gas, vapour, or dust classification in relation to the group or subgroup of the equipment, e.g. IIA, IIB, or IIC.
  • External influences and ambient temperature.

TLP (Tension Leg Platform)

UL (Underwriters Laboratory)

A company that certifies, validates, tests, inspects, audits, advises and trains. www.uk.com

UEL (Upper Explosive Limit)

Concentration of flammable gas, vapour or mist in air, above which an explosive gas atmosphere will not be formed. Although a mixture which has a concentration above the upper explosive limit (UEL) is not an explosive gas atmosphere, it can readily become so and, in certain cases for area classification purposes, it is advisable to consider it as an explosive gas atmosphere. There are some gases which are explosive with the concentration of 100 %.

USGC (United States Coast Guard)

www.uscg.mil/

See as an example for offshore installations in USA waters, Code of Federal Regulations (CFR) DOT/USCG 46 CFR Parts 110 – 113 Shipping Subchapter J. Electrical Engineering.

Valve Actuator

Device used to open, close, or control valves. Actuators may be electrical, hydraulic and pneumatic. Movement may be quarter-turn or multi-turn. Actuators may be used, for example, when (a) valves are remotely located (e.g., on pipelines) (b) valves are located in hazardous areas (c) manual operation would be time-consuming (e.g., with larger valves).

WOCS (Workover Control System)

WOCS may provide hydraulic control of subsea tree functions and/or a pilot control system for the riser system.

 
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Bifold, Bifold Fluidpower, Bifold Subsea, Bifold Orange and Marshalsea Hydraulics Ltd are all members of the Bifold Group.

Registered No. 1787729 in England.

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