Although an inexpensive, replicated part may look the same as an original part and may fit into the valve being repaired, it does not meet the original valve manufacturer’s design specifications. This article describes the problems with non-OEM parts, and explains why parts from the original valve manufacturer are far superior.
Non-OEMs supply valve parts to the process industry at prices up to 30 to 40 percent less than the list price from the original manufacturer, and claim to meet or even exceed the quality of the original parts. But, they don’t meet specs in many cases, which can cause serious problems. Karl Lanes, senior director of global parts at Emerson, explains the situation in his article The Dangers of Non-OEM Valve Parts in Valve World magazine:
A valve that does not meet the original valve manufacturer’s design specifications can cause leaks and prevent a valve from controlling properly, and often does not last as long as the OEM alternative would. It can also fail completely, preventing the valve from operating, and causing an entire process to be shut down at a cost of hundreds of thousands of dollars per day.
Why is it so hard to duplicate a valve part? Karl explains:
To duplicate a part, a non-OEM machine shop must first measure it to estimate all the proper dimensions. In most cases, the non-OEM machine shop may measure only one part. That part may be used, worn or damaged, especially if it was removed from a valve under repair.
The worn part is likely to be significantly out of spec. But even if the measurements are accurate and correctly identify the part’s dimensions, this does not represent the part’s complete design specifications. Even if they measure a brand-new part, they can still produce a substandard replicate part. Karl points out that this can cause widespread problems:
When a non-OEM produces a substandard part, it might just adversely affect a single valve produced for one customer. But if the non-OEM continues to use the same measurements to supply similar parts to multiple customers, it could be distributing substandard parts widely.
Emerson is often called upon to evaluate failed parts from non-OEM suppliers. After evaluating dozens of substandard parts, our engineers made a statistical analysis on the reengineering process of measuring a machined part’s dimensions. The analysis determined that when a machinist tries to measure an OEM part to duplicate it, it’s almost impossible to replicate each dimension of the OEM part, since the machinist has no idea which side of the tolerance that specific part’s dimension was machined to originally. Karl explains the difficulty this poses to non-OEMs:
The engineering team calculated that it would take measurements from 35 unique and new OEM parts of the same part number to determine the actual manufacturing tolerances. It’s highly unlikely that the non-OEM replicator would purchase 35 OEM parts just to sell one part, let alone duplicate that investment for literally thousands of valve parts.
Is a 30-40% cost savings worth the risk of using substandard parts? Not if it leads to excess maintenance, poor performance or outright valve failure:
A complete failure is rare but can happen when a replicator does not have the product expertise to understand design limitations. This can lead to a dangerous plant situation, causing a plant to shut down, or causing a more serious incident