Last year US industry spent over $600 billion on plant and equipment maintenance. According to industry experts, at least 33% of such expenditures or $200 billion was wasted. Other industry statistics suggest that 72% of all failures of plant and equipment are outlined by infant mortality failure model. About 6% of equipment shows aging related wear out failure pattern (John Moubray: RCM II). This means that failures happen in the early stage of assets lifecycle, and interventions, instead the general believe, at the end of useful life of assets of age related failures. 

Could we align efforts to reverse these impressive statistics? Current requirements of the industry, requires efficiencies in every single aspect of your business. Engineering groups are not an exception. Assets care is the main responsibility of an engineering unit and with statistics shown, adequate commissioning practices are required to assure proper performance of equipment on early stage of lifecycle. As part of a system start up, commissioning has been a tool to identify if assets are performing as expected according to design criteria. Traditional Commissioning ensures that the finished facility operates as intended. It uses a programmed series of design and construction documentation and testing activities that verify the functional operation of the equipment. It typically checks operating parameters such as pressure, temperature, minimum and maximum airflow, lighting levels, electrical amperage and voltage, torque, fluid volumes, and other thermodynamic measures to confirm that the design intent has been met. Focus of such commissioning has been only aligned to process parameters and not equipment condition. CBM (Condition Based Maintenance) is a key element in trend setting organizations to assure equipment performance is not part of actual failure probability statistics. Thus adding CBM to enhance commissioning practices will provide not only assurance of assets delivering operational parameters, but how the asset is performing to achieve such parameters.

In rotating equipment, it is not unusual to discover equipment operation problems after a construction, overhaul of an asset or major renovation project. Some of those problems are caused by misapplied design, but most of them are caused by latent manufacturing defects, poor installation practices, and damage incurred during transportation and handling. As an example, recent experience with new construction at two NASA Centers and a major facility of another Federal Agency revealed 85 – 100% of the rotating equipment at the acceptance phase to be either misaligned, out-of- balance, or contained defective bearings. In most of the above cases, the faulty equipment would have passed the specified acceptance criteria. This same equipment would most likely experience premature failure during actual operation if the problem conditions were not corrected. Premature failures decrease system safety, reliability, and efficiency, and often disrupt ongoing critical operations. The costs associated with that premature failure not only could have been avoided with better acceptance criteria, but the costs of correcting the problem should be the responsibility of the contractor.

There is an exceptionally high cost associated with a bad design, either because the equipment is unable to properly satisfy function, equipment life is shortened, or because operations and maintenance cannot be properly performed. Ensuring a good equipment design can overcome many of these issues, as well as overcome premature failure to some extent. Recognize that this practice may cause costs to escalate. Those additional costs must be weighed in relation to the perceived value and benefits achieved. Preferred approach is to eliminate those premature failures and achieve those additional benefits without unnecessarily enhancing the design, and therefore keeping costs to a minimum.

            In summary, commissioning provides partial assurance of your systems performance and could be enhanced complementing typical operational parameters checklist with traditional CBM techniques like vibration analysis, thermography, shaft alignment check, motor current analysis, tribology, non destructive testing, to create a quantum leap of improvement to current commissioning practices.

 

By: George Santos Norat, BSEE, PE

12SEP2008

PdMtech, Inc