Tubesheet in Deep-hole Drilling

When it comes to deep-hole drilling in tubesheets, the tolerance requirements are typically more stringent due to the critical nature of the application. Deep-hole drilling refers to the process of creating deep, precise holes in thick materials like tubesheets.

The specific tolerance for deep-hole drilling in tubesheets can vary based on factors such as the material being drilled, the hole diameter, and the intended application. However, some general guidelines for tolerances in deep-hole drilling include:

Concentricity: Deep-hole drilling requires maintaining high concentricity between the drilled hole and the outer surface of the tubesheet. Typical concentricity tolerances for deep-hole drilling range from ±0.001 inches (±0.0254 mm) to ±0.005 inches (±0.127 mm), depending on the size and depth of the hole.

Straightness: The drilled hole should be as straight as possible. Straightness tolerances for deep-hole drilling can range from ±0.005 inches per foot (±0.41 mm/m) to ±0.020 inches per foot (±1.67 mm/m), again depending on the size and depth of the hole.

Surface finish: Deep-hole drilling should result in a smooth and uniform surface finish. The required surface finish will depend on the specific application but is often specified in terms of roughness average (Ra). Common Ra tolerances for deep-hole drilling range from 32 to 125 microinches (0.8 to 3.2 micrometers).

It's important to note that these tolerances are general guidelines and may vary based on the specific requirements of your project or industry standards. Consulting with an engineer or referring to relevant industry codes and specifications (such as ASME B&PV Code) is recommended to determine the precise tolerance requirements for deep-hole drilling in tubesheets.