There are industry standards. Different refrigerants have different wall thickness standards for copper tubes.
The thickness of R4 10a refrigerant is 0.75, and 19.05 is generally 0.75 or 0.8mm, so the air-conditioning copper tube must be able to withstand certain pressure. The copper tube of air conditioner is 0.8 mm thick, light in weight, good in thermal conductivity and high in low temperature strength. Commonly used in refrigeration equipment. Air conditioning refrigeration copper tube has the characteristics of firmness and corrosion resistance.