8/3/2019 2004 11 Unapproved Procedure Change = Fire

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CCPAn AIChE Industry

Technology Alliance

CCPAn AIChE Industry

Technology Alliance

CENTER FOR

CHEMICAL PROCESS SAFETY

AIChE 2004. All rights reserved. Reproduction for non-commercial, educational purposes is encouraged. However, reproduction

for the purpose of resale by anyone other than CCPS is strictly prohibited. Contact us at ccps_beacon@aiche.org or 212-591-7319

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What Happened?What Happened?

Why did this Happen?Why did this Happen?

What you can doWhat you can do

PSID members see: Free SearchMOC and Free SearchVacuum Column

Thoroughly Evaluate ChangesKnow, Dont Guess the Consequences!

This small stripper was used to separate a lightsolvent from a heavier oil. Annually, the unitwas shut down for internal inspection and

cleaning. The practice had been to allow 24hours for cooling down before startingmaintenance work and opening the stripper.

This time, the shutdown team decided to shortenthe cool down period to 12 hours to reduce the

time the unit would be out of service.

The unit was shut down, allowed to cool for 12hours and then the stripper was opened. Almostimmediately, smoke began to come out of theopen manway. There were no visible flames andno one was injured, but it was obvious that

something had caught on fire.

A Long Standing Procedure was Changed

without Understanding ALL Consequences!

It was believed that the 24 hour cool down

period was to protect workers from hot

surfaces. No one understood that those

same hot surfaces might cause residual

solvent or oil to catch on fire.

Oxygen was introduced in to the vessel before

the temperature had dropped below the

autoignition point of some of the residual

materials. This completed the fire triangle by

adding oxygen to the fuel and heat already

present.

Unapproved Procedure Change = Fire

Understand the reason for each processingand maintenance preparation step.

Dont assumeKNOW!

Know how and when to use your facilitys

management of change (MOC) process. Ask to

be sure that all changes have been reviewed and

approved before taking action.

The process safety information should

contain autoignition temperatures if the process

operates above them. If your process does,

make sure you are well below those

temperatures before allowing air to enter.

Equipment containing chemicals must be

cooled below the autoignition temperature

before opening!

PProcessrocessSSafetyafetyBBeaconeaconhttp: //www.aiche.org/ccps/safetybeacon.htm

Messages for Manufacturing Personnel

November 2004Visit the CSB document on MOC at:

http://www.csb.gov/safety_publications/docs/moc082801.pdf

his edition is also available in German, French, Spanish, Portuguese and Chinese. Contact CCPS at ccps_beacon@aiche.org for informatio

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