Problems existing in the construction of on-site pump foundations

The pump foundations on site mainly have the following issues: 1. The depth of the holes for the foundation anchor bolts is insufficient. The installation requirements for pumps stipulate that the elevation should be within ±5 mm of the specified value. To meet this elevation requirement, the anchor bolts must be at least 10 mm above the bottom of the hole. The solution is to raise the elevation appropriately as long as it still satisfies the pump’s suction requirements and the needs of the process piping; if an excessive increase is necessary, then the holes for the anchor bolts must be drilled deeper until the required depth is achieved； 2. Location of the anchor bolt holes: The installation requirements for the pump specify that the coordinate position must not exceed 20 mm. While ensuring that the pump is installed in the correct position, the distance between any point on the anchor bolt and the wall of the hole must be at least 15 mm; if this distance is less than 10 mm, the anchor bolt holes need to be enlarged ； 3. The base elevation is too low. Under normal circumstances, the thickness of the grouting layer, that is, the height at which the shims are installed, should not exceed 70 mm. If the base is too low, it is necessary to use the grouting method when installing the shims; if the elevation is too low, a second grouting layer must be applied, usually using high-strength grouting material. Before applying this material, the surface of the base must be roughened and cleaned to prevent cracks from forming in the future ； 4. If the foundation elevation is too high, generally the thickness of the grouting layer should be no less than 30 mm, and the installation height of the shims should be at least 25 mm. In cases where the foundation is too high and the shim installation height is less than 25 mm when the required installation elevation is to be met, the surface of the foundation must be chiseled until the shim height requirement is satisfied ； 5. Damage to the foundation due to physical factors: Given the complex construction conditions on site, it is common for large equipment or pipes to cause damage to the foundation. Such damage is usually limited in scope, and it can be repaired by setting up formwork during the secondary grouting of the pump ； 6. Settlement of the foundation: Since the ground surface beneath the equipment was not prepared during the initial construction phase, rainwater may cause localized settlement or tilting of the equipment foundations. In such cases, it is necessary to continue monitoring for further settlement. If it is confirmed that the foundation is no longer settling, leveling can be achieved through secondary grouting; if settlement continues, the area around the foundation should be excavated and the bottom of the foundation filled with grouting material ； 7. The base surface should be roughened; for pump installation, the surface that is to undergo secondary grouting must have a rough texture, with the depth of these rough spots being no less than 10 mm. There should be 3 to 5 such spots per square decimeter, and the surface must be free of oil stains or loose layers ； 8. Defects in the basic appearance such as cracks, honeycombing, voids, and exposed rebar. 9. Debris such as gravel and soil, as well as standing water, in the anchor bolt holes must be removed completely ； 10. The relative position and geometric dimensions of the pump foundation must conform to the design specifications. Hehe, that’s about all I know. I hope it’s useful to you!

What was said upstairs is already very comprehensive and professional; I would like to add two more points: 1. Attention should be paid to the bearing capacity of the ground at the location where the foundation is constructed, as this affects the depth of excavation for the foundation pit, the size of the foundation pad, as well as the methods used for constructing the foundation； 2. The setting out for foundation construction must be accurate to avoid misalignment of the pump, which would make piping work more difficult.

One end of the pump foundation that was newly installed in our company has sunk by 5 mm. We’re not sure if this will affect its performance; it’s a large-scale pump with a power rating of 1000 Kw