Comparison Of Flange Face Finish As Per B16-5 5t53g

Flange Face Finish (Surface Finish) is refer to ANSI B16.5

There are 2 unit systems that usually used for Flange Face Finish : a) RMS = Root Mean Square b) AARH = Aritmetic Average Roughness Height There are some equation we can use to measure Flange Face Finish : a) RMS = 1.11 x Microinches (Ra)…………… (equation 1) b) AARH = Ra x 0.0254…………………………… (equation 2) c) Ra = AARH / 0.0254……………………………. (equation 3) Note : Ra = Microinches AARH = Micrometers There are some requirement that usually used for Flange Face Finish : a) Stock Finish : < 63 AARH b) Smooth Finish : 3.2 – 6.3 AARH

Example : Condition Valve standard for flange face finish is 125 – 250 Ra. Customer request for smooth finish (3.2 – 6.3 AARH).

Solution We can use equation 2 to check whether Valve standard can comply customer requirement or not. AARH = Ra x 0.0254

AARH = Ra x 0.0254

AARH = 125 x 0.0254

AARH = 250 x 0.0254

AARH = 3.175

AARH = 6.35

AARH = 3.2

AARH = 6.3

From this equation we can find the result that 125 – 250 Ra is equal with 3.2 – 6.3 AARH, which means Valve standard is comply with customer requirement.