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RE: Five why's = root cause analysis

Hi Michelle,


Boy, talk about a defeatist end statement.  Why ask why if you’re going to end the line of questioning with a statement that equates to “because that’s the way we’ve always done it and we’re not going to change.”  I would prefer to see:


ü      Why is this type of corrosion protection absolutely necessary? Because the parts are stored outdoors, exposed to weather.


So is the root cause corrosion protection or improper storage leading to corrosion?  Ferrous iron parts will rust if exposed to moisture and air.  Why do they have to be stored outdoors?  Moving the parts inside into a controlled environment might avoid the potential for corrosion.  Another benefit of indoor storage is that the parts will not be chilled down overnight, this sometimes leading to rejects in the morning (the cold metal may upset temperature control on the hot process baths).


One problem I have with the “5 why’s” concept is that it is too limiting to the problem at hand.  I believe it’s better to ask 10 why’s or 100 why’s until you have exhausted all potential options.  Why use solvent, why use oil, why use this particular oil product, why allow the parts to rust, why make the parts out of steel, why not buy the parts already painted or plated, etc., etc.  Just my 2 cents.


Mike Callahan, PE

Jacobs Engineering

1111 S. Arroyo Parkway

Pasadena CA, 91105

(626) 568-7005 office

(213) 359-9805 cell


-----Original Message-----
From: owner-p2tech@great-lakes.net [mailto:owner-p2tech@great-lakes.net] On Behalf Of michelle gaither
Sent: Sunday, March 01, 2009 1:05 PM
To: p2tech
Subject: Five why's = root cause analysis


I am looking for a good example of drilling down with 5 why's - relating to a chemical issue.


here is an example, but i don't like this example because we don't have a solution.  (a few alternatives/potential solutions to this one would be great - or a completely different example.


Thanks in advance for any suggestions.



Asking “why” five times is a simple way to identify the root cause of a waste, and that makes it easier to identify ways to reduce or eliminate the waste. Here is an example:


ü  Why is the solvent a waste? Because the solvent is contaminated with oil.


ü  Why is it contaminated with oil? Because the solvent was used to clean oil off the parts.


ü  Why are the parts oily? Because the manufacturer puts a coating of oil on them before shipping them to this facility.


ü  Why does the manufacturer put a coating on them? To prevent the parts from corroding after manufacture.


ü  Why is this type of corrosion protection absolutely necessary? There is no other way to protect the parts from corrosion.


In this example, the root cause of the solvent waste is corrosion protection. 


Source: Arizona Department of Environmental Quality, Pollution Prevention Analysis and Plan Guidance Manual, March 2006, www.azdeq.gov/environ/waste/p2/download/first.pdf.

Michelle Gaither | environmental engineer
1402 Third Ave, Suite 1420 | Seattle, WA 98101
T 206.352.2050 | F 206.352.2049| www.pprc.org

Pacific Northwest Pollution Prevention Resource Center
practical solutions for economic and environmental vitality


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