Proper commissioning of an ISG vertical pipeline centrifugal pump directly determines its long-term operational stability, reduces unexpected downtime, and prevents premature wear on critical internal components. Every step must follow established field practices, with careful attention to system conditions before, during, and after initial startup.

Pre-start system inspection

Before any power is applied, the entire connected piping system should be fully reviewed to eliminate hidden installation errors that could cause immediate damage. Confirm that the pump body flow arrow aligns exactly with the direction of medium movement in the pipeline, as reversed installation will break the designed hydraulic balance and reduce output pressure significantly. Check that all independent pipe supports are securely fastened, so no additional structural stress transfers to the pump flanges or distorts the pump casing.
Manually rotate the pump shaft by hand to verify the rotor assembly turns smoothly, with no scraping, binding, or unusual resistance that suggests misaligned internal parts. Clear all welding slag, rust particles, and construction debris from the upstream piping, and confirm the inlet filter is properly seated to block solid contaminants from entering the impeller chamber. Verify that all flange bolts are tightened diagonally with even force, and that no sealing gaskets are misaligned or protruding into the flow path.

Prime and vent the pump chamber

ISG vertical pipeline centrifugal pumps are not self-priming, so complete venting before startup is essential to avoid air binding that stops the pump from building consistent pressure. Open the inlet gate valve fully, and leave the discharge gate valve in a nearly closed position to reduce initial motor load. Slowly pour the conveyed medium into the pump chamber through the dedicated vent plug opening, allowing trapped air to escape steadily from the highest point of the pump casing.
Continue adding medium until a continuous, bubble-free stream flows out from the vent opening, then tighten the vent plug securely. Do not rush this process, as even a small pocket of remaining air can trigger cavitation during operation, creating noise, vibration, and repeated damage to the mechanical seal faces. For systems with long suction lines, repeat the venting process at the highest points of the inlet piping to ensure no isolated air pockets remain trapped upstream.

Motor direction verification and initial startup

Never run the motor continuously before confirming correct rotation, as prolonged reverse operation will unbalance the impeller, wear down the seal assembly, and place abnormal axial load on the motor bearings. Perform a short, controlled jog of the motor, then observe the shaft rotation direction from the top of the motor housing to confirm it matches the specified clockwise orientation. If rotation is incorrect, adjust any two phases of the power supply connection before proceeding.
After confirming correct rotation, start the motor with the discharge valve still nearly closed, then gradually open the outlet gate valve to bring the system up to the designed operating flow point. Watch the pressure gauge reading on the discharge side to ensure it stabilizes at the expected working pressure, rather than fluctuating sharply or dropping below the system’s required NPSH value. During the first 30 minutes of continuous operation, monitor motor current, surface temperature, and overall vibration level to confirm all readings stay within the normal operating range. Check all flange connections and seal points for signs of slow leakage, and make minor adjustments to valve positions if the system flow or pressure does not match design specifications.