Avoid Surprises During Pump Startup

Aug. 26, 2010
A well-thought-out approach can eliminate potential problems.

Everything went smoothly. We'd followed ISO-9001 standards to the letter. Even our as-built one-line schematics were perfect. Management was amazed. I was not.


To achieve this "miracle" we eliminated risk, one item at a time. We selected the right equipment, followed quality control checks, and carried out field inspections from construction through commissioning with dogged determination.

After placing the order for the pumps, I started to plan commissioning. We updated piping and instrumentation diagrams, then one-line diagrams, instrument details and all the termination drawings. With this first set of drawings done, we moved on the pressure-test planning, pipe spool details, test instruments, structural supports, sewer drains, tie-in lists, and finally distributed control system (DCS) programming. In no time, our Gantt chart was pretty beefy.

Here're some tips for success:

Upon delivery, inspect each pump to confirm it matches file information and specification. This may require disassembly. In most cases, put in seals or replace existing ones. Don't perform final alignment until the pump is installed. Confirm the quantity of spare parts and that each conforms to specifications. Inspect all pipe spool parts like check valves to ensure the removal of check stops.

Now, move on to the motor. Review the starter bucket and other components against the motor nameplate information; check the branch circuit loads for capacity. You'd be surprised how many times someone tries to run a 230-VAC motor with a 460-VAC starter. The heaters, contactors and overload relays all should be within specifications. Before pump installation, test the supply side of the starters for faults such as an unbalanced leg. Balance is important. Deviation of the current from the average of the three legs (L1, L2, L3) should be less than 2%; voltage to a 460-VAC starter should be within 440–480 VAC and at the correct frequency. Greater than a 1% difference in voltage measured between L1/L2, L1/L3 or L2/L3 will cause the motor to fail from overheating the rotor. Check to ground, too.

If everything is okay at this point, it's time to install the pump in the field. Before grouting the pump frame to its base, confirm that a suitable concrete coating is applied and that the base is level — if not, shims will be needed, and shims corrode. Verify drainage around the pump base.

Next, inspect the piping. Confirm the spools match the drawings. Here's a general checklist: 1) pipe is supported independently, not on the equipment flanges; 2) there are no abrupt tees or elbows that could promote water-hammer; 3) all arrows on check valves and other equipment point in the correct directions; 4) vent valves and sample valves are where they should be; 5) expansion is allowed at the pump inlet; 6) suitable reducers are installed on the pump inlet and outlet; 7) the seal plan is correct; 8) obstacles such as valve handles won't snag operators; 9) lifting lugs and bolts and temporary add-ons such as a suction strainer and items for pressure testing are in place; and 10) instruments are spaced correctly for steady flow. Follow pressure testing with a complete flushing of the piping around the pump. Ideally, use a flush pump such as an air-diaphragm unit, not the process pump; isolate it with pancakes.

Now that the pump has passed the mechanical testing, it's time for electrical and instrumentation. Meg and check the voltages between the motor's wiring box (peckerhead) and the starter. You'll want to eliminate any variations between: L1/L2, L1/L3, L2/L3 and L1 to ground, L2 to ground, and L3 to ground. Assuming you don't find any shorts or equipment failures, align the pump and motor and conduct the load test. Confirm lubrication for the pump and grease the motor.

Ensure instruments are in working order. Instrument testing is fairly straightforward. Begin with a communication test, checking continuity between the field and DCS. Confirm pump protection, such as pressure switches, without starting the pump. Start the pump manually.

Radial pumps start best with the discharge valve opened gradually; axial pumps are opposite. Make sure the pressure gauge is positioned on the pump discharge so that fully developed flow is measured. The pump should be on its system curve. Now, use it to calibrate control valves and flow transmitters, set timers and establish flow through recirculation lines.

Once the system is operating, perform any baseline work you'll want for the future. Here's some ideas to consider: 1) an infrared scan of the motor, starter and variable frequency drive, if present (for the motor, allow a day to run); 2) characterizing flow control valves; and 3) vibration testing.

Eliminating problems along the way will allow your startup to go smoothly.

Dirk Willard is a Chemical Processing Contributing Editor. You can e-mail him at [email protected].

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