Check the surface of the stainless steel bolt for visible defects, and do not allow defects such as bumps, napping, deformation, cracks, thread damage and loose fitting.
Use a magnifying glass, coloring flaw detection, or magnetic particle inspection to check for cracks in the transitions between the rounded corners of the stainless steel bolts and the threads.
Measuring stainless steel bolt length
The length of the stainless steel bolt was measured to find the permanent deformation of the stainless steel bolt. When the four-stroke diesel engine connecting rod stainless steel bolt elongation exceeds 2% of the original design length, it should be scrapped.
The elongation or necking of the stainless steel bolts is mostly caused by excessive force during installation, or the stainless steel bolts of the connecting rod are subjected to excessive tensile stress when the cylinder is pulled or bitten by the diesel engine. When installing stainless steel bolts, the stainless steel bolts are mistakenly tightened as much as possible, so that the nuts are excessively tightened, causing the stainless steel bolts to deform or break. For example, the 6135 diesel engine requires a torque of 180 to 200 N·m for tightening the connecting rod stainless steel bolt. If it is close to 400 N·m, the stainless steel bolt will be elongated or necked; if it reaches 450 N·m, the stainless steel bolt will break.