Ford’s Missing AND Gate

Ford’s Missing AND Gate
Credit Reuters

Update to the Update

Antonov An-124 used by Ford
Antonov An-124 

Ford management has made a huge effort to get around the problem created by having just the one supplier of a critical component. And they were successful. They even used the enormous Antonov An-124 freight carrier to fix the problem as quickly as possible. In process safety terms, it could be said that their emergency response program functioned well. Nevertheless, it does appear as if the incident will affect their second quarter earnings.

It is also interesting to note that the Ford Motor Company had another ‘AND Gate’ problem. They have announced that they plan on substantially reducing their focus on cars in North America. So the loss of F-150 production becomes even more serious. Their business plan takes out one more “safeguard”.


Update

BSEE Safety Alert AND GateThe Bureau of Safety and Environmental Enforcement (BSEE) has just issued  a Safety Alert (Floating Production Platform Evacuated Amid Power Outage). Most of this Alert is to do with the failure of electrical systems. But it is interesting to note, once again, the AND Gate problem crops up. Form the report,

 

Additionally, the ventilation in the battery room was not working properly, which prevented exchange of air volumes and contributed to the continuing perception of a fire and explosion risk. Closed dampeners, plugged filters, and failure of motor controllers contributed to the ventilation deficiencies.


Starting this week (May 10th 2018) the Ford Motor company will suffer severe setbacks in the production of its very profitable line of F-150 pickup trucks due to a fire at one of the supplier plants. Evidently Ford has just the one supplier for this critical component.

What does this have to do with Process Safety? Well, any system that has no redundancy is very vulnerable to the failure of the single item. Which is why we have redundant safety systems. For example, high pressure in a vessel can be addressed by the following events and responses.

  • IF the pressure in the vessel rises
  • AND IF the instruments do not control the pressure rise

  • AND IF the operator does not take corrective action

  • AND If the safety instrumented system does not take over

  • AND IF the pressure safety relief valve does not open

  • THEN the vessel will explode

In Fault Tree parlance, this is an AND Gate. And it is AND Gates that lie at the heart of process safety systems. The following sketch shows the AND Gate for the above items.

Vessel High Pressure AND Gate

(Strictly speaking, the ‘Pressure Rises’ is the initiating event with a frequency value, whereas the other items are safeguards with dimensionless probability values. So there should be two AND Gates — one for ‘Pressure Rises’ and the other for the output of the AND Gate of the safeguards.)

As a rule of thumb, the best way of improving safety is to add redundancy, rather than upgrading the availability of existing safety systems.

This serious interruption to F-150 may also point up some of the risks to do with Just in Time (JIT) management. If Ford had maintained a larger inventory of components the cutbacks in production would not have been so immediate.

In other Ford news, the company has decided to exit the sedan business in the United States and to concentrate on F-150 truck production. There’s another missing AND Gate. The company has concentrated its attention on one product line and made that product line dependent on one supplier.

Too many eggs in one basket
Credit Bing

Copyright © Ian Sutton. 2018. All Rights Reserved.