In most cases, pump manufacturers are concerned about the effects of overheating equipment, but what do you need to know about horizontal pumps when the temperature dips below freezing? Even in warmer regions, it can be hard to predict the magnitude of a winter storm until it strikes. To help operators understand the effects of persistent winter conditions and avoid expensive repairs, we’ve developed this list of 6 steps to protect your horizontal pumping equipment in response to freezing events.
Please note: it’s recommended to keep horizontal pumping systems in operation during freezing conditions. Keeping the motor energized and pumps rotating will prevent the internal components from seizing. However, this is not always feasible. This list provides general tips for restarting operations after freezing has occurred.
Step 1. Thaw the Pump and Suction Housing
Even assuming the pump has been properly drained, there is still a likelihood that residual fluid in the pump has solidified into ice. It’s better to assume there is enough ice present to prevent rotation of the pump impellers and shaft than to cause internal damage on start-up.
To bring the idle pump to a temperature above freezing, you can use heat tracing devices such as thermal blankets, heat lamps, or heat tape.
DO NOT use a flame to heat the equipment – this is extremely dangerous.
Step 2. Check the Instrumentation
Instrumentation that is in contact with the process fluid (such as transmitters at the suction housing and the discharge locations), as well as the hydraulic lines connecting the instrumentation, may freeze in the timeframe where operations are suspended.
If these components are obstructed by ice in any way, it will prevent the proper monitoring of the pump’s overall operation. For the best results, remove the ice and bring these components up to a satisfactory operating temperature using the methods listed above.
Step 3. Warm Up the Motor
Motors are typically designed to operate in environments where ambient temperatures are -20C (-4F). Additionally, some motors may contain heating elements that will activate upon shutdown to minimize condensation from forming between the stator and the rotor.
Unless noted on the nameplate, industrial motors (common to those used on HPS equipment) should be able to operate in extreme cold environments. However, if there is any doubt, you can use any of the methods listed above to increase the general temperature state of the motor.
Once operational, the motors will generate ample heat to improve the efficiency characteristics of the unit.
Step 4. Ensure Internal Temperature of the Variable Speed Drive is Above Freezing (When Applicable)
If a variable speed drive controller is part of the horizontal pump configuration, it’s always good practice to ensure the internal temperature of the drive is above freezing before starting the unit.
If space heaters exist within the equipment, they can be used to warm the internal parts of the drive, or heat-tracing equipment can be used.
Step 5. Circulate Thrust Chamber Oil
Freezing temperatures can cause metals to contract, most notably affecting the narrow clearances between bearings in a horizontal pump thrust chamber. Therefore, it is critical to ensure that oil can properly lubricate the internal components before operating the equipment.
Thrust chambers that operate with an external cooler may contain an auxiliary heating element within the reservoir to prevent condensation from forming while the unit is not in operation. When the equipment is idle, this device should be energized to maintain the oil temperature at a constant level.
If the cooler’s auxiliary heater has been de-activated for a long-term duration (whereby the oil temperature is near that of freezing) it is recommended the operator engage the heating element to warm the oil. Due to the size of the cooler’s reservoir, this process may take several hours.
Once the oil is above 50F, the cooler’s oil should be circulated through the thrust chamber to ensure proper lubrication.
Step 6. Do Not Attempt to Lift Equipment
Unless the equipment is specifically designed to operate in extreme frigid conditions, the standard materials used to construct a horizontal pump and frame may not be able to withstand impact loads and/or thermal shock, specifically when subjected to below-freezing temperatures.
If the materials have not been rated for prolonged freezing conditions, a phenomenon known as “brittle fracture” may result and occur without warning. This can affect the integrity of lift hooks and other supporting components, so failing to take precautions in these conditions can have deadly consequences.
Always consult the manufacturer prior to lifting any HPS equipment (even at the designed lifting locations) especially when temperatures are below the freezing point.
Conclusion
Completing these steps prior to energizing your horizontal pumping system will help reduce the likelihood of failure and therefore avoid the need for repairs and unplanned downtime.
After start-up, we recommend monitoring the system to ensure it is running properly and check for leaks, high vibration, and head loss, as these issues may require additional maintenance.
More Than Just an Equipment Supplier
Valiant is committed to ensuring profitable performance over the life of your operations. From routine on-site maintenance to versatile equipment retro-fitting, optimization, and monitoring, we offer full lifecycle support for a range of surface pumping applications. In addition to designing systems to meet customers’ standard and high-spec requirements, Valiant configures all Aquarius horizontal pumps with a focus on long-term performance, durability, and ease of maintenance to reduce your cost of ownership and extend equipment run life.