PISTA BLOG#12 (July 2022):IDENTIFICATION OF FLAMMABLE ZONES OFFSHORE O&G PLATFORMS

  IDENTIFICATION OF FLAMMABLE ZONES 

ONBOARD OFFSHORE OIL & GAS PLATFORMS

 ZONE 0, ZONE 1, & ZONE 2- HAZARDOUS AREAS

        Explosions on board an offshore installation may occur if sufficient flammable liquids, vapors, gases, or even combustible dust start a fire or in some cases suddenly set off a devastating explosion. Such situations may arise in most offshore workplaces such as Platforms, Rigs, FPSO and FSO, Refinery processing units, sampling areas, storages area, etc.

 A hazardous area on board an Offshore O&G Platform or rig can be defined as “any location where there is a RISK OF AN EXPLOSION”.

However, every hazardous area is different, and each area may have specific requirements depending on the atmosphere's nature and the elements present there. They are directly dependent on the type of operations being undertaken there. Globally, there have been countless examples over the years, of the disasters caused in explosive atmospheres.

For an explosion to occur, explosive or flammable gases, vapors, mists, or specks of dust need to be present. After the presence has been identified, the level of risk of an explosion is categorized based on:

•  The FREQUENCY of the occurrence of an explosive atmosphere and
•  The DURATION of the occurrence of an explosive atmosphere.

 This level of risk in this case is represented by classifying the hazardous area as

ZONE 0, 

ZONE 1 OR 

ZONE 2 (for Gas, Vapour, and Mist Atmospheres) or

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ZONE 20,

ZONE 21 OR

ZONE 22 (for Combustible Dust Atmospheres.)

LET’S TAKE A CLOSER LOOK AT WHAT DEFINES ZONE 0, ZONE 1 & ZONE 2 HAZARDOUS AREA CLASSIFICATIONS.

There are three necessary components for an explosion to occur;

1. FLAMMABLE SUBSTANCE/ MATERIAL (this needs to be present in a relatively high quantity to produce an explosive mixture (e.g. gas, vapors, mists, and dusts).

2. OXYGEN – oxygen is required in high quantities and in combination with the flammable substance to produce an explosive atmosphere.

3. SOURCE OF IGNITION – a spark or high heat must also be present. 

     On Oil & Gas platforms mandatory precautions are already put in place to prevent fires and explosions, wherever there is potential for an explosive atmosphere. Electronic equipment, and machinery, including lighting, are purpose-designed for use in such hazardous areas to prevent sparks from occurring and then igniting any flammable substances.

     On a case-to-case basis and for the ease of monitoring and specification a classification of each hazardous area is carried out (such as Level or “zone”).

 All hazardous area equipment must be designed with hazardous area zone classifications in mind, as the “zone” governs the level of protection and precaution required. It is essential to know which zone a work needs to be carried out, so that the most appropriate equipment may be specified for use.

 For gases, vapors, and mists the zone classifications are recognized as Zone 0, Zone 1 & Zone 2 areas.

          LET’S UNDERSTAND WHAT CRITERIA DEFINE EACH ZONE:

 1.             ZONE 0 is an area in which an explosive atmosphere is present continuously for long periods or will frequently occur.

 2.             ZONE 1 is an area where an explosive atmosphere is likely to occur in normal operation occasionally. It may exist because of repair, maintenance operations, or leakage.

 3.             ZONE 2 is a place in which an explosive atmosphere is not likely to occur in normal operation but, if it does occur, will persist for a short period only. These areas only become hazardous in case of an accident or some unusual operating condition.

  Mandatory and regulatory obligations of employers regarding risk identification and management of risk from such potentially explosive atmospheres to protect their workers include:

• Performing explosion risk assessments before the commencement of work
• Performing hazardous area classification
• Implementing prevention and protection measures against explosions
• Coordinating all worker’s health and safety measures implementation and stating them in the explosion protection document
• Creating and updating explosion protection document

WHAT IS THE SUFFICIENT LEVEL OF SAFETY FOR EQUIPMENT TO BE USED IN SUCH POTENTIALLY EXPLOSIVE ATMOSPHERES?

    The level of safety of equipment required is dependent on the likelihood of flammable gas or flammable dust atmosphere arising. The demands that need to be put on equipment when operating in such a place are higher in case the likelihood of a flammable atmosphere being present are stronger. Should an explosion nevertheless occur which could directly or indirectly endanger personnel, damage the equipment, and affect the property, it is crucial to halt
it immediately and/or to limit the range of explosion flames and explosion pressures to a sufficient level of safety.

 The Combustible Dust areas also have similar criteria; we shall understand them in detail in our future PISTA BLOGS.

OPITO IN INDIA-PISTA OFFSHORE