THMG276 – It Depends…Part 3

In this series of shows we will be tackling something that is typically an Operations concern. Behavior modeling and exploring how it questions the age-old answer, “It Depends?!?”

Plus a question from the ol’ mailbag

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A.          Breach

1.    When a container is stressed beyond its limits of recovery, it opens or breaches and releases its contents

a.     Different container types breach in different ways based on a variety of factors (including internal pressure)

b.     The type and extent of breach depends upon the type of container and the stress applied

2.     First responders should try to predict they type of damage that may result from the stress that is being or has been applied

3.     The nature of a breach is a major factor in planning offensive product control operations

4.     Types of breaches include

a.     Disintegration — Occurs in containers that are made of a brittle material (or that have been made more brittle by some form of stress)

i.       The container suffers a general loss of integrity
ii.      Examples of disintegration include a glass bottle shattering or an exploding grenade

b.    Runaway cracking — Breaks the container into two or more relatively large pieces (fragmentation) or large tears

i.       A crack develops in a container and continues to grow rapidly
ii.      Runaway cracking often occurs in closed containers, such as drums, tank cars, or cylinders
iii.    Runaway linear cracking is commonly associated with BLEVEs

c.     Attachments (closures) open or break — May fail, open, or break off when subjected to stress, leading to a total failure of a container

i.       When evaluating an attachment (such as a pressure-relief device, discharge valve, or other related equipment) that failed, first responders should consider the entire system and the effect of failure at a given point

d.    Puncture — Occurs when foreign objects penetrate through a container, such as forklifts puncturing drums and couplers puncturing a rail tank car

e.  Split or tear — Containers may also breach through a split, such as a welded seam on a tank or when a drum fails

i.       Mechanical or thermal stressors may cause splits or tears, such as when a seam on a bag of fertilizer rips

B.          Release

1.    When a container fails, its contents, energy, and the container itself (whole or in pieces) may release

a.     If a cylinder of pressurized, chlorine gas suffers an attachment failure at the valve due to mechanical stress, the product (a toxic, corrosive oxidizer) releases along with a substantial amount of energy (because of stored pressure), which rapidly accelerates the valve and/or cylinder in the opposite direction from the release

b.     Depending on the situation, this release can occur quickly or over an extended time period

c.      Generally, large amounts of stored chemical/mechanical energy result in a more rapid release, presenting a greater risk to first responders

2.    Releases are classified according to how fast they occur

a.    Detonation — Instantaneous and explosive release of stored chemical energy of a hazardous material

i.       The duration of a detonation can be measured in hundredths or thousandths of a second
ii.      An explosion is an example of a detonation
iii.    This release could result in
(a)      Fragmentation
(b)      Disintegration
(c)       Shattering of the container
(d)      Extreme overpressure
(e)      Considerable heat release

b.    Violent rupture — Immediate release of chemical or mechanical energy caused by runaway cracks

i.       Violent ruptures occur within a timeframe of one second or less
ii.      These releases result in ballistic behavior of the container and its contents and/or localized projection of container pieces/parts and hazardous material
iii.    A BLEVE is an example of a violent rupture

c.      Rapid relief — Fast release of a pressurized hazardous material through properly operating safety devices

i.     This action may occur in a period of several seconds to several minutes
ii.      Damaged valves, damaged piping, damaged attachments, or holes in the container can result in rapid relief

d.    Spill/leak — Slow release of a hazardous material under atmospheric or head pressure through holes, rips, tears, or usual openings/attachments

i.Spills and leaks can occur in a period lasting from several minutes to several days

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