Are Large Amendments Needed for Our Rotating Equipment Specifications?

By Fred K. Geitner, P.Eng.

I heard the complaints of several technical managers of an EPC (Engineering, Procurement, Construction) company. They were complaining about the proliferation of voluminous technical specifications for rotating equipment: reams and reams of paper in addition to commonly used industry standards. They felt that there were frequent duplications and contradictions in such specifications, frustrating them or the vendors, and causing costly delays. While these specific complaints were directed towards rotating equipment specifications, especially for compressors, the same can often be said for other equipment specifications (e.g., pressure vessels, heat exchangers, storage tanks, etc.).

In an effort to capture the accumulated knowledge and experience of equipment end-users and manufacturers, the American Petroleum Institute (API) developed a series of engineering standards which, since the mid 1950s, have found widespread acceptance both in the United States and worldwide. The primary purpose of API standards for rotating equipment is to establish minimum mechanical requirements. This limitation in scope is consistent with API’s overall charter.

At first, not every purchaser understood that API standards required the purchaser to specify certain details and features. Experienced users of critical machinery had been doing just that. They were modifying, deleting, amplifying, and adding to API rotating equipment standards to reflect their particular operating or maintenance experience and preferences, and to ensure that the machine had the desired degree of reliability, maintainability, accessibility, inspectability and thus, availability for its specific application. They supplemented API standards with specification addenda or amendments according to Table 1. Note that the respective needs of both purchaser and manufacturer were, and still are, best served by supplementing a given API standard, rather than by rewriting it or incorporating sections from it into another complete technical specification. To do otherwise needlessly increases the number of pages that must be read by all parties and increases the possibility of errors.

Now it seems that this effort has gone too far. We would like to make the point that API rotating equipment standards have reached a mature level based on experience gained over many years. After all, we are looking at the Seventh Edition of, for example, API 617, Axial and Centrifugal Compressors and Expander-Compressors for Petroleum, Chemical and Gas Industry Services, and even the Tenth Edition of API 610. This begs the question: Is it really still necessary to expand these standards to sometimes double their size by amending them as described above?

As we look around, we find that larger end-user companies seem to get along with a minimum of amendments to the API standards. The only additions generally seem to be related to site safety, environmental impact, or reliability driven improvements. These are typically covered in a one or two page document. The rest of the technical specification basically just follows the API standard.

While I want to encourage readers to curtail the business of modifications and additions, I nevertheless realize that there is still a good deal to be accomplished by a knowledgeable and experienced specifying engineer. Two points need to be mentioned:

So what are we trying to say? I recommend that technical management start looking at specification volumes with the objective of reducing them to the point where an awareness exists that every single modification (see Table 1) of an existing industrial standard should require some cost-benefit driven justification. All specification packages should comply with the essential elements of good specifications, namely:



Figure 1 - Typical API-Type Compressor Lube Oil Reservoir