Health&Safety_Semi

• Opportunities for fires


  • In petrochemicals, refining, manufacturing, and oil and gas production
  • Fires are just another hazard employees must guard against
  • Tankfarms of numerous large and small storage tanks
  • Spherical liquefied natural gas storage tanks
  • Pipelines full of flammables
  • Reactors, distillation towers, drums, etc.
  • Fuel is everywhere in enormous quantities around the working employees
  • Air is everywhere around vessels containing fuels and flammables
  • Loss of containment and the right air-fuel mixture combined with a source of ignition
• The Occupational Safety and Health Administration (OSHA) has mandated certain standards for fire protection in 29 CFR 1910.155-165
• Fire and explosion accidents

  • Major concern to the owners and operators of refineries and petrochemical, gas processing, terminal, and offshore facilities
  • Majority of monetary loss in these types of complexes is due to fire and explosion
  • 65% of accidents due to vessel (container) and vapor cloud explosion
  • 35% of accidents due to fire
  • Causes mostly attributed to mechanical issues, process upset, and operator error
• Corporations have an enormous investment in their processing plants
• Even fires that did not obviously appear to have damaged vessels, pipes, or pumps may have altered the integrity (metallurgy) of the equipment so that they must be replaced at great expense
• Industry investment in fire prevention

  • Fire detection
  • Firefighting equipment
  • Firefighter training
  • Fire fighting drills
  • Fire trucks
  • Fire monitors and turrets
  • Fire brigades
  • Bunker gear
  • Locally mounted fire extinguishers
  • Fire pumps and fire water
• Fire prevention and fire fighting are critical issues with processing industries
• Classes of Fires


  • Class A
  • Class B
  • Class C
  • Class D
• Class A Fires


  Solid materials such as wood, paper, plastic, housing, etc.
• Class B Fires


  Flammable liquids and gases
• Class C Fires


  Electrical (within breaker boxes, motor control centers, etc.)
• Class D Fires


  Combustible metals, such as aluminum, magnesium, and titanium
• Without a source of fuel, there is no fire hazard
• Types of Fuels


  • Solids
  • Liquids
  • Vapors
  • Gases
• Solid Fuels


  Wood, building decorations, furnishings such as fabric curtains and wall coverings, and synthetics used in furniture
• Wood and textile can be treated with fire or flame-retardant chemicals to reduce their flammability but under the right conditions they will still burn</b>
• Solid fuels are involved in most industrial fires, but the presence of flammable liquids and gases is a major cause of industrial fires
• Flash Point


  The temperature for a given fuel at which vapors are produced in sufficient concentration to flash in the presence of a source of ignition
• Fire Point


  The minimum temperature at which the vapors will continue to burn given a source of ignition
• Flammable Liquids


  Liquids with a flash point below 100°F
• Combustible Liquids


  Liquids with a flash point at or higher than 100°F
• Most flammable liquids are lighter than water, so water cannot be used to put out a fire involving them
• Many gases are lighter than air, so released into air, gas concentrations are difficult to monitor due to the changing factors of air, current direction, and temperature
• Reducing Fire Hazards


  1. Eliminate sources of ignition

  2. Prohibit smoking near fuels

  3. Prevent electrical sparks near fuels

  4. Isolate open flames from fuels

  5. Isolate tools/equipment that may produce sparks from fuels
• Fire Watch


  A technician assigned to survey work in a certain area, keep the area clear of combustible material, maintain permit conditions, prevent actions that would result in the release of flammable substances, and sound the alarm in the event of a fire
• Petrochemical and refining sites have their own firefighters, fire trucks, and firefighting gear, and have a mutual aid agreement with nearby plants to assist each other in case of fire
• Firefighters have regularly scheduled drills where they respond to a fictional fire on a specific unit
• Many plants use a combination of systems to detect, suppress, and/or fight fires, with many of the systems alarming to a remote location such as the site's emergency management office or guard building
• Automatic fire detection systems

  Used in most industries today to warn of the presence of smoke, radiation, elevated temperature, or increased light intensity
• Types of fire detectors

  • Thermal expansion detectors
  • Photoelectric fire sensors
  • Ionization or radiation sensors
  • Ultraviolet or infrared detectors
• Thermal expansion detectors


  Use a heat-sensitive metal link that melts at a predetermined temperature to make contact and sound an alarm
• Photoelectric fire sensors


  Detect changes in infrared energy radiated by smoke or by the smoke particles obscuring the photoelectric beam. A relay closes to complete the alarm circuit when smoke interferes with the intensity of the photoelectric beam.
• Ionization or radiation sensors


  Use the tendency of a radioactive substance to ionize when exposed to smoke. The substance becomes electrically conductive with the smoke exposure and permits the alarm circuit to be completed.
• Ultraviolet or infrared detectors


  Sound an alarm when the radiation from flames is detected
• Fire suppression


  Inhibiting the growth and spread of fires
• Methods of fire suppression

  • Isolation
  • Water
  • Gas extinguishants
  • Foams
  • Solid extinguishants
• Isolation of fuel from the oxidizer


  Can be accomplished by closing an upstream valve to isolate the source of fuel, or by blanketing with an inert gas or foam
• Water as a fire extinguishant


  Cools the burning fuel below its ignition temperature. Water applied as a spray or fog also absorbs heat of vaporization and breaks chain reactions, reducing the concentration of oxygen and lowering the rate of combustion.
• Gas extinguishants


  More effective than water in some cases, especially for fires in enclosed spaces with valuable equipment. Cause no water damage or dry powder damage, and have no messy cleanup.
• Carbon dioxide as a gas extinguishant


  Acts as a coolant, a blanketing agent, reduces oxygen levels, and inhibits combustion