Defining Your Pump System Requirements: Criteria for General Scope Document

For those of you just tuning in, this is the third in a series of articles regarding preparation of a pump system specification, specifically the general scope document (GSD) that the end user should prepare for submitting to the engineering, procurement and construction (EPC) firm when requesting a proposal. RELATED: Podcast with William Livoti on common reasons why pump systems are poorly designed From my experience, I have found the end users with a very solid, clearly defined GSD have the most reliable, efficient pumping systems. On the flip side, the end users who leave the entire specification process in the hands of a “third party” have the most problematic systems. “You won’t get anything you don’t ask for.” Let me explain the above quote. If you want to get what you want, you need to ask. Otherwise the engineering firm will not know what you want, and you will wind up with the lowest first cost system that meets whatever criteria you shared with the engineering design firm. To that end, in my last article on preparation of the GSD (Pumps & Systems, April 2018), we addressed planned improvements and future expansion. This included:

• developing a team—all parties that have a vested interest in the system
• identifying who has system specification responsibility—the stakeholders. Engineering, maintenance, operations, production, purchasing and reliability have interests and concerns relative to the project, and they are all valid.

In this article, we will begin addressing the pump, motor, variable speed control and piping. Again, let me remind you we are defining the design criteria, not the overall system specification. However, the GSD defines the end users’ goals, expectations and owner’s acceptance criteria (OAC). Beginning with the pump, the team members determine what they expect (as the equipment owners) from the pump relative to pump configuration, reliability/mean time between repair (MTBR), efficiency, maintenance, cost (spare parts), service, process control, load range, vibration and decibels, to name a few. I have performed many pump system assessments over the years and just as many root cause failure analysis studies. In more than a few instances, I have found the pump was incorrectly specified. When I begin asking questions regarding system design and specifications I typically receive the following response: “We left the selection up to the engineering design firm.” My next question: “Did you provide the engineering firm any type of criteria for the pumping system?” After some discussion, the answer is no. Developing pump criteria is an art form that requires three things: clear communication, high involvement (from the team) and a strong working knowledge of pumps. In other words, it requires a combination of being articulate, highly involved and knowledgeable. The engineering firm often pushes back on some portions of the scope document, and the pump is typically at the top of the list. When developing pump criteria, you can refer to several pump standards, including Hydraulic Institute (HI) and American Petroleum Institute (API), with the API Standard being the more detailed. I often use API Standards when specifying pumps for one simple reason: they have “teeth” that provide optimum reliability. The rub comes when you refer to API for, say, a boiler feed pump or perhaps a water pump in a chemical plant. It is not uncommon for the engineering design firm to object by stating this is not an API application. Your response should be, “I’m using the API Standard for your benefit and mine.” The standard is readily available and clearly defined, which makes it easy for the engineering firm. The tight standard ensures you, the end user, a well-designed, robust pump for your plant. API has an excellent installation specification (API 686) that can be referenced in the GSD. We will address installation in the OAC portion of the GSD. In my next column, I will provide a data sheet specific to pump selection. Until next time, remember clarity is power.