Friday, July 29, 2011

Heinz Bloch Failure Codes as a Simple Start to Failure Coding

I get quite a few request for these simple failure codes for use in Enterprise Asset Management Systems (EAMS) and Computerized Maintenance Management Systems (CMMS) so I thought I would post them up for easy retrieval.

Remember failure codes are only as good as the understanding the user has of each code, so make sure to create training for your team and test for understanding prior to implementation.

If you use these examples as a failure coding system then please understand this is a first step and as your organization matures with failure reporting you may chose to go to a more in-depth  failure code structure that is based off of the Failure Modes Effects Analysis (FMEA) that you complete. This will provide a new level of detail for reliability engineers and maintenance engineers to use in there quest to investigate,eliminate, and mitigate failures.

These definitions are drawn from the Heinz Bloch Machinery Failure Analysis and Troubleshooting book third edition. We have taken them and added examples. They can be a good first step on the way to Failure Reporting Analysis and Corrective Action System (FRACAS) within your EAM or  CMMS.

Faulty Design (FD)
Faulty design is when the equipment is not adequate for the intended service. Generally this results in conditions (i.e. temperature, force, pressure, vibration, etc.) which were not expected from the design and exceed the equipment capabilities.

“In excess of 95 percent of fluid handling problems were either designed in or the result of a process change that did not account for its effects on all equipment.” Charles M. Boyles, Editor, Pumping Technology Magazine

Material Defects (MatD)
A material defect is a flaw in the material itself, such as a casting defect, or a non-uniform material (i.e. metal, elastomer, etc.) which results in a material property (i.e. strength, hardness, elasticity, chemical resistance, etc.) different than those expected.

The material defect category should not be used when the wrong material is used in a particular service. This would be the result of a faulty design if the material was designed to be used or a fabrication error if the correct material was called for, but not used.

Fabrication or Processing Errors (FPE)
A fabrication / processing error indicates that the equipment and / or parts are not made correctly (as designed) during initial fabrication or are improperly re-conditioned during a repair. These errors can be identified by verifying whether the components adhere to the original design (i.e. proper dimensions, fits and clearances, proper material, correct component balance, etc.).

Assembly or Installation Defects (AID)
An assembly / installation defect generally means that the equipment and/or parts may have been made correctly, but were not put together or installed correctly. This would include the assembly or repair of the equipment as well as field installation, which may result from improper or inadequate procedures or techniques. Assembly problems may include items such as improper bearing installation / handling procedures, incorrect orientation of grease shields, improper torque sequences, etc. Field installation problems may include items such as shaft misalignment, inadequate grouting, piping strain, etc.

Off-design or Unintended Service Conditions (USC)
An off-design / unintended service condition usually means that the design was adequate for the original service, but changes to the service have now made the design inadequate for the new service conditions. This can occur when changes have been made intentionally to the operating (service) conditions creating an unintended effect on the equipment (condition the equipment was not designed for). Examples may include a throughput change that causes cavitation or a temperature change that affects a material strength.

This failure category can occur when plant capacity is increased without a sufficient review of the effect on equipment. “We have found that a large percentage, 27%, of chronic machine and system problems is the direct result of operating production systems outside their acceptable design range.” - Keith Mobley, President, Integrated Systems, Inc

Examples: Equipment damage due to external acts such as lightning and other acts of nature as well as damage due to mobile equipment operator carelessness and intentional management changes to the SOPs.

Maintenance Deficiencies (MD)
A maintenance deficiency indicates that the equipment is not maintained correctly after it is designed and installed. This may include not replenishing / changing lubricants, not changing filters when they plug, allowing contamination to go untended (i.e. water or dirt in oil), or using inadequate procedures to perform such tasks (i.e. not removing the drain plug when re-greasing bearings).

The maintenance deficiency category would not normally be used to classify a problem that results from an improper repair. That type of defect would normally be the result of either a fabrication / processing error or an assembly / installation defect.

Improper Operation (IO)
As the name implies, improper operation results when the equipment is not operated correctly. This usually occurs with unintended changes to the equipment operating conditions. Examples would include such things as running a pump dry, deadheading a pump for prolonged periods of time, operating in a critical frequency for prolonged periods, as well as improper operating procedures (i.e. not venting a seal chamber to remove gas prior to commissioning).

Improper operation is often associated with upset conditions in the system or transient type conditions such as start-up and shutdown.

Examples: Incorrect or poorly written SOPs

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