Lap joints are a type of joint used in engineering and fabrication where two overlapping plates or pieces of material are joined together. The joint is created by overlapping the plates and then fastening them together with bolts, screws, or welding.


The thickness of the plates being joined is an important factor to consider when deciding whether to use a lap joint. Different thickness ranges are suitable for different joint types.

- Option a) Less than 3 mm: Lap joints are commonly employed on plates with a thickness less than 3 mm. This is because lap joints are relatively simple to construct and provide sufficient strength for thin plates. The overlapping of the plates distributes the load across a larger area, reducing stress concentrations and increasing the joint's strength.

- Option b) 5 to 10 mm: Lap joints can be used on plates with a thickness of 5 to 10 mm, but other joint types may be more suitable for thicker plates. As the thickness increases, lap joints may not provide enough strength and rigidity, and other joint types such as butt joints or T-joints may be preferred.

- Option c) 125 mm: Lap joints are not typically used on plates with a thickness of 125 mm. This thickness is considered quite large, and lap joints may not be able to provide the required strength and stability for such thick plates. Other joint types, such as butt joints or fillet welds, are more commonly used for thicker plates.

- Option d) Above 25 mm: Lap joints are also not commonly employed on plates with a thickness above 25 mm. As the plate thickness increases, lap joints become less effective in providing the required strength and load-bearing capacity. Thicker plates often require more robust joint designs, such as butt joints or T-joints, to ensure structural integrity.

In conclusion, lap joints are commonly used on plates with a thickness less than 3 mm. For thicker plates, other joint types may be more suitable to provide the required strength and rigidity.