06-12-2012, 03:45 PM
Prevention of Over - Pressurization
[attachment=42798]
What is Over-Pressurization?
The increase of pressure inside a piece of equipment beyond its ability to hold that pressure.
Vessels and tanks
Cylinders and bottles
Compressors and pumps
Piping and tubing
Hoses and flex joints
Instruments and valves
Over-Pressurization Hazards
Ruptured process vessels, cylinders, piping
Whipping hoses
Flying debris and shrapnel
Serious injury
Death
Over-Pressurization Kills
Incident 1: Liquid trapped in the ball of a ball valve expanded, causing the valve to come apart. Worker dies when contents of CO2 storage tank released in his direction.
Incident 2: A chlorine cylinder ruptures during fill procedure, killing worker in the same room.
Causes of Over-Pressurization
Faulty process control
Process upsets
Trapped liquefied gases
In a pipe or hose between two closed valves
In a ball or gate valve not designed to relieve internal pressure
Faulty Process Control
Improperly calibrated control devices (temperature, pressure, flow, level…)
Malfunctioning control sensing device such as:
Isolation valves closed
Inlet ports blocked
Devices damaged
Trapped Liquefied Gases
Expand as they warm and vaporize
Pressure rises can exceed most process valves, piping and hoses pressure ratings
If no vapour in the trapped space, hydraulic loading can occur - leads to extremely high pressures in a very short time
[attachment=42798]
What is Over-Pressurization?
The increase of pressure inside a piece of equipment beyond its ability to hold that pressure.
Vessels and tanks
Cylinders and bottles
Compressors and pumps
Piping and tubing
Hoses and flex joints
Instruments and valves
Over-Pressurization Hazards
Ruptured process vessels, cylinders, piping
Whipping hoses
Flying debris and shrapnel
Serious injury
Death
Over-Pressurization Kills
Incident 1: Liquid trapped in the ball of a ball valve expanded, causing the valve to come apart. Worker dies when contents of CO2 storage tank released in his direction.
Incident 2: A chlorine cylinder ruptures during fill procedure, killing worker in the same room.
Causes of Over-Pressurization
Faulty process control
Process upsets
Trapped liquefied gases
In a pipe or hose between two closed valves
In a ball or gate valve not designed to relieve internal pressure
Faulty Process Control
Improperly calibrated control devices (temperature, pressure, flow, level…)
Malfunctioning control sensing device such as:
Isolation valves closed
Inlet ports blocked
Devices damaged
Trapped Liquefied Gases
Expand as they warm and vaporize
Pressure rises can exceed most process valves, piping and hoses pressure ratings
If no vapour in the trapped space, hydraulic loading can occur - leads to extremely high pressures in a very short time