Common Hazards

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Common Hazards

One of the philosophies that lies behind Process Safety Management (PSM) is that each chemical process is unique. Therefore it is not possible to have a prescriptive standard that tells operating companies what to do. Instead, companies have to identify the unique hazards associated with their facility, and then implement corrective actions based on a risk-ranking methodology. For this reason, facilities covered by PSM standards have to conduct a series of Process Hazards Analyses (PHAs), often using the Hazard and Operability (HAZOP) methodology.

 Yet most process facilities are not unique; technologies, equipment types and management styles tend to quite similar from plant to plant and from company to company, particularly within specific industries. Hence, many of the hazards that exist on these facilities are quite similar to one another. Some of the more commonly-observed hazards are discussed in this section; they are grouped into the following categories:

• Process hazards;
• Hazards of utilities;
• Hazards of water;
• Hazards of steam;
• Hazards of ice;
• Hazards of compressed gas;
• Hazards of air;
• Hazards of external events;
• Hazards of equipment and instruments; and
• Hazards of piping, valves and hoses.

Contents

Introduction
Process Hazards
   High Flow
   Low / No Flow
   Reverse Flow
   Misdirected Flow
   High Pressure
   High Temperature
      Blocked-In Pump
      Polymerization
      External Fire
   Low Pressure
   Low Temperature
   High Level
   Wrong Composition
   Chemical Embrittlement
   Strong Oxidizers
   Static Electricity
Hazards of Utilities
   Common Cause Failure
   Process Contamination
   Electrical Power Failure
   Nitrogen
   Reverse Flow to a Utility Header
   Survivability of Utilities
Hazards of Water
   Water in Very Hot Liquid
   Water and Firefighting
Hazards of Steam
   Steaming Vessels during Turnaround
   Reboiler Leak
   Wet Steam in Turbines
Hazards of Ice
   Line Freezing
   Hydrates
Hazards of Compressed Gas
   Gas Cylinders
   Pigging
Hazards of Air
   Flammable Mixture
   Blowing a Line Clear
Hazards of External Events
   Flooding
   Earthquakes
Hazards of Equipment and Instruments
   Furnace Firing
   Fired Heater Burnout
   Multiple Uses of Equipment
   Distributed Control Systems
Hazards of Piping, Valves and Hoses
   Piping
      Pipe Class Transition
      Hydraulic Hammer
      Pig Launchers and Receivers
      Pressure in Relief Headers
      Flame Propagation through Drains
      Overload of Overhead Vacuum Lines
      Underground Piping
      Vents and Bleeders
   Hoses
      Hoses and Truck Pull-Away
      Hose Run Over
      Hose Failure
      Temporary Connection
   Valves
      Block Valves below Relief Valves
      Fail-Safe Control Valves
   Shared Relief Valve
   SDV Bypass