Key Points for Selecting Seamless Tubing

The seamless tubing is a widely used component for pipe connections, especially in systems requiring high pressure resistance and sealing. Selecting the right seamless tubing requires consideration of multiple factors, including surface finish, material, hardness, and wall thickness. Here is a brief seamless tubing selection guide for your reference.

Surface Cleanliness

The surface cleanliness has a significant impact on the flow efficiency and corrosion resistance of pipelines. A smooth inner surface can reduce frictional resistance during fluid flow, lower energy consumption, and prevent the accumulation of contaminants.

Table 1: Comparison of Surface Cleanliness of Pipes of Different Materials
Product/Cleanliness Level	General Fluids μm (μin.)		Sanitary Grade μm (uin.)		Pure Grade μm (uin.)
Product/Cleanliness Level	Outer Surface	Inner Surface	Outer Surface	Inner Surface	Outer Surface	Inner Surface
AP Tubing	Ra ≤ 0.8 (32)	Clean	–	–	–	–
BA Tubing	–	–	Ra ≤ 0.6 (25)	Ra ≤ 0.6 (25)	Ra ≤ 0.6 (25)	Ra ≤ 0.38 (15)
Seamless Coil	Ra ≤ 0.6 (25)	Ra ≤ 0.6 (25)	Ra ≤ 0.6 (25)	Ra ≤ 0.6 (25)	Ra ≤ 0.6 (25)	Ra ≤ 0.38 (15)

Material

Stainless Steel. It is suitable for most environments, especially those requiring good corrosion resistance.
Carbon Steel. It is suitable for environments not involving strong corrosive media.
Copper. With good thermal conductivity, electrical conductivity, corrosion resistance, and ductility, it is mainly used for hot water supply and transportation of some chemicals
Aluminum. It features lightweight, good corrosion resistance and thermal conductivity.
Alloy Materials. It is suitable for extreme environments, such as high temperature, high pressure, or highly corrosive media.

Outer Hardness

Hardness directly affects the wear resistance and mechanical strength of the pipeline. Choosing materials with moderate hardness helps to avoid brittle fracture in high-pressure environments.

Hardness of stainless steel tubing: 90 HRB (200 HV) or less
Hardness of carbon steel tubing: 72 HRB (130 HV) or less
Maximum hardness of alloy 400 tubing: 75 HRB
Maximum hardness of alloy C276 tubing: 100 HRB
Maximum hardness of alloy 20 tubing: 95 HRB
Maximum hardness of alloy 600 tubing: 92 HRB (198 HV)
Hardness of SAF 2507 super duplex steel tubing: 32 HRC or less
Maximum hardness of alloy 825 tubing: 201 HV
Maximum hardness of alloy 625 tubing: 25 HRC (266 HV)

Wall Thickness

Wall thickness is an important factor for designing pipes to withstand internal and external pressures. Pipes of different materials have different wall thicknesses and can withstand different working pressures. For more details, please check the seamless tubing catalogue.

When selecting seamless tubing, it is necessary to consider these factors comprehensively to ensure a safe, reliable, and cost-effective pipeline system. If you encounter any problems in choosing seamless tubing, please feel free to contact us.