Surface Roughness Conversion Chart of Stainless Steel Tube By yaang.com

Stainless Steel Tube's Surface roughness —also known as surface profile Ra—is a measurement of surface finish -- it is topography at a scale that might be considered "texture" on the surface. Surface roughness is a quantitative calculation of the relative roughness of a linear profile or area, expressed as a single numeric parameter (Ra).
Stainless Steel Tube's Surface roughness is the measure if the finer surface irregularities in the surface texture. These are the result of the manufacturing process employed to create the surface. Stainless Steel Tube's Surface roughness Ra is rated as the arithmetic average deviation of the surface valleys and peaks expressed in micro inches or micro meters. ISO standard use the term CLA (Center Line Average). Both are interpreted identical.

Ra micro-meters	Ra micro-inches	RMS	CLA (N)	Rt	N	Cut-Off Length
						in.	mm
0.025	1	1.1	1	0.3	1	0.003	0.08
0.05	2	2.2	2	0.5	2	0.01	0.25
0.1	4	4.4	4	0.8	3	0.01	0.25
0.2	8	8.8	8	1.2	4	0.01	0.25
0.4	16	17.6	16	2.0	5	0.01	0.25
0.8	32	32.5	32	4.0	6	0.03	0.8
1.6	63	64.3	63	8.0	7	0.03	0.8
3.2	125	137.5	125	13	8	0.1	2.5
6.3	250	275	250	25	9	0.1	2.5
12.5	500	550	500	50	10	0.1	2.5
25.0	1000	1100	1000	100	11	0.3	8.0
50.0	2000	2200	2000	200	12	0.3	8.0

Conversions (math):

CLA (micro inches) = Multiply Ra(µm) x 40

RMS * (acceptable 1.1 - 1.7 factor) = Multi

ply CLA x 1.1

Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)