Applications for high-temperature pumping with multistage water pumps can be found in virtually every sector of the economy. The maximum demand for vertical pumps is in over-allowed temperature. Acquiring the necessary skills to manage is necessary to ensure a reliable operation. Pumping occurs at high temperatures for a variety of reasons, including the following:
- The liquid must be heated for it to transform from a solid or semi-solid state into a fluid state so that it can be moved, handled, or placed with greater ease.
- A method that involves the application of heat as a catalyst in order to either begin or continue a chemical reaction.
- A fluid designed specifically for the purpose of transferring thermal energy from one heat source to another.
In each of these situations, the pumps are susceptible to the effects of dimensional changes brought about by the thermal expansion of the pump components as a direct result of the movement of hot liquid through the pump. These changes can cause the pumps to become out of alignment or cause other problems. In the process of sealing the pump shaft in high temperature pumping applications, the mechanical seal is exposed to axial movement, which is typically caused by changes in dimensions. It is possible for the pump shaft to grow axially into the seal chamber if the temperature at which the pump is running is different from the temperature at which the pump casing is heating up, as well as if the rates of thermal expansion and heating are different. 
The following factors might contribute to shaft overgrowth, depending on where the shaft is located within the room-temperature sealant chamber:
- When the pump is heated to start, different heating rates are applied to the shaft depending on how the pump body is being heated.
- According the fact that the pump casing and shaft are made of different building materials, there are differences in the thermal expansion rates of both components (which cause the shaft to grow during heating and temperature).
The axial growth of the shaft will be more proportionate to the distance that the packing is from the thrust bearing. These impacts are minimal since the designs of single-stage pumps use shafts that are significantly shorter than other pump designs. These effects, however, become more pronounced as the length of the column grows and new layers are added. These effects are seen most strongly in multistage pumps with bearings located between stages. The thrust bearing for an inter-bearing pump is typically situated at the end of the non-driven pump in its typical configuration. As a direct consequence of this, the drive-side seal chamber generally goes through the most expansion of the axle shaft. The location of the pump installation on the baseplate (with the feet installed on the center line), the design of the pump, and the presence of piping that causes thermal stress on the pump's suction and discharge are three additional elements that may affect the thermal growth of a shaft. 
Pump makers build pumps to allow less axial movement that could arise from heat expansion. Despite this, it is constantly present. The difficulty that comes with employing a mechanical seal is that the design of the seal assembly needs to be able to accept this displacement without impacting the sealing function. Knowing the size and direction of the displacement is essential in order to overcome this issue (within the house). Either very tight or very loose). In most cases, this is established through measurements taken in the field or through analytical procedures carried out by the pump manufacturer at the particular temperature at which the pump would be operating. In addition, many multistage pumps incorporate angular contact thrust bearings, which can have an axial play of up to 0.01 cm (0.025 in). This allows the pumps to operate more smoothly (0.65 mm [mm]). In most cases, the thrust bearing clearances need to be increased when working with pumps that have certain spring pressure compensating mechanisms. In order for pump and seal engineers to have a comprehensive understanding of the axial position of the shaft while it is operating, bearing clearances and expected shaft motion during start-up should be discussed between the two groups. In general, a mechanical seal in the manner of a high-temperature cartridge may withstand axial displacement of up to 0.040 in. (1 mm) in each direction from the seal mounting point when the temperature is at room temperature. 
After the displacement has been calculated, it can be matched up with the functional capacities of the mechanical seal. A face seal cartridge assembly can be designed as a displacement compensation solution for circumstances in which the amount of displacement approaches or surpasses the seal limits. These kinds of situations can arise in a variety of settings. This is accomplished by regulating the position of the rotating assembly of the mechanical seal on the shaft while it is at room temperature. This is done so that when the pump reaches its operating temperature, the thermal expansion of the shaft will move the seal to the position that it is intended to be in while it is in use. When performed in this manner, the mechanical seal has the capacity to withstand axial displacement in one direction of up to 0.080 inches (2.0 mm) in usual circumstances. The internal clearances in the mechanical seal assembly and, more critically, the axial movement capability of the seal are what determine the limits to the amount of axial growth that can be accommodated by this method. There are limits to the number of axial growth that can be accommodated. As a point solution for situations in which applications require a greater axial stroke than is possible with typical mechanical seal designs, makers of mechanical seals have the capability of creating customized long-stroke designs. These solutions are adaptable to accommodate shaft axial displacements that are more than 0.5 millimeters (0.2 inches) (5 mm). Following the installation and commissioning procedures outlined by the equipment manufacturer is the best way to ensure that a pump designed to operate at high temperatures functions correctly. 
The following is a synopsis of two of the most important procedures involved in getting a high-temperature pump ready for initial operation. It is crucial to remember that the requirements that need to be taken into consideration are far more extensive than those that are listed in this outline. Alignment checks: After being lubricated, properly aligned shafts contribute more than anything else to extending the life of bearings, seals, and rotors than any other factor. They ensure a reduction in vibrations, a reduction in bearing loads, a reduction in power loss, and a reduction in wear. Checks of the alignment of the drive joints need to be performed whenever:
- Variations in the temperature of the process
- line changes
- Either the pump or the engine have been completely refurbished.
The procedure of alignment verification consists of two steps:
- Initial Alignment Check (Cold) - Carried out prior to operation when both the pump and the driver are at their normal operating temperature.
- Final Alignment Check (Warm): Carried out when both the pump and the driver have reached their normal operating temperature. After the system has had some time to warm up or after a brief period of operation, you can perform this step.
Refer to API RP 686: Acceptable Techniques for Machinery Installation and Installation Design, published by the American Petroleum Institute (API), for additional information on recommended pump installation practices.