Task or Environmental Conditions » LTA task planning

12Failure To Isolate Compressed Air Line



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Brief Description of Incident/Accident & Description of Consequences/Outcomes:

In an Underground coal mine two parallel pipe branches comprising a 100mm compressed air line and a 100 mm pump line had been installed. The task was to install pipe closures to join these pipe branches to the main line. Tee pieces had been installed into the main lines to receive each of the branches. All the pipes were suspended from the roof by chains. Connected to each Tee section in sequence were a 100 mm butterfly valve, 25 mm valve and a end cap. Both these lines were 100 mm galvanised pipes with Victaulic clamps of the quick release lever type. The pump line closure had been installed and preparations were being made to install the air line closure. The 100mm butterfly valve on the air line had been closed and the end of the tee section bled of pressure through the 25mm valve. A miner was attempting to remove the end cap by releasing the quick release clamp. The end cap was ejected from the end of the pipe under pressure striking the miner in the face causing severe injuries.

Identified Root Causes:

Pipe arrangement: As determined to be the case immediately before the accident The investigation determined that the tee section of the 100 mm compressed air line was pressurised prior to releasing the end cap and concluded that the 100 mm isolation valve had been inadvertently reopened before the attempt was made to remove the end cap.

Energy Type(s) Involved:

Stored Energy in Compressed Air Lines

Equipment Type(s):

Compressed Air Reticulation System Equipment

Root & Contributing Cause(s):

LTA pressure control

Stated or Potential Consequence(s):

Potential Fatality

Preventative/Recommended/Accepted Steps of Risk Mitigation, Points of Interest:

Mine isolation procedures should be reviewed to determine adequate isolation of compressed air and release of stored energy similar to electrical isolation procedures.

Personal danger tags and/ or locks should be applied to the isolating valve.

Pipe installations should provide adequate means to bleed pressure once isolation is effected, the fitting of a bleed valve to end caps is considered a good measure.

A standard work procedure should detail the standard for installation and layout of pipes.

The marking and identifying of pipes and valves should be in accordance with relevant Australian Standards.

Valves should be clearly distinguished where the potential for confusion between valves is recognised as a hazard.

Organisation:

Queensland Government Department of Employment, Economic Development and Innovation (DEEDI)


Results

Here are the results.


Information

Reference Type:

Safety Alert #1

Mine Type:

Any Mine Type

Energy:

Potential & Kinetik - Pressure

Equipment:

Published:

2000

Region:

Australia, Queensland



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