tailieunhanh - Machinery Component Maintenance and Repair Part 4

Tham khảo tài liệu 'machinery component maintenance and repair part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 110 Machinery Component Maintenance and Repair Figure 3-34. Baseplate core sample with zinc primer. Baseplate designs have become less rigid over time. Attention has been focused on the pump end of the baseplate to provide enough structural support to contend with nozzle load requirements. The motor end of the baseplate is generally not as rigid as shown in Figure 3-35. The process of shipping lifting storing and setting the baseplate can have a negative impact on the motor mounting surfaces. Although these surfaces may have initially been flat there often is work to be done when the baseplate reaches the field. Using the system of jack bolts and anchor bolts of Figure 3-36 the mounting surfaces can be reshaped during the leveling process but the Machinery Foundations and Grouting 111 Figure 3-35. Underside of American Petroleum Institute API baseplate. concepts of flatness and level have become confused. Flatness cannot be measured with a precision level and unfortunately this has become the practice of the day. A precision level measures slope in inches per foot and flatness is not a slope it is a displacement. In the field flatness should be measured with either a ground straightedge or bar and a feeler gauge as shown in Figure 3-37 not with a level. Once the mounting surfaces are determined to be flat then the baseplate can be properly leveled. This confusion has caused many baseplates to be installed with the mounting surfaces out of tolerances for both flatness and level. The other issue of mounting surface distortion comes from the grout itself. All epoxy grout systems have a slight shrinkage factor. While this shrinkage is very small typically 7in the tolerances for flatness and level of the mounting surfaces are also very small. The chemical reaction that occurs when an epoxy grout resin and hardener are mixed together results in a volume change that is referred to as shrinkage. 112 Machinery Component Maintenance and Repair Figure 3-36. Anchor bolt