CleanFLOW Valves

Measuring and specifying surface finish has, until recently, been left to a varying amount of speculation. The number of different standards being used by different equipment manufacturer has created a great deal of confusion and misunderstanding throughout the industry. With the advent of ASME/BPE the pharmaceutical and biotechnology industries finally have a standard that can be universally applied.

*Table SF-5 Acceptance criteria for interior surface finishes of valve bodies

Anomaly or Indication

Acceptance Criteria

Cluster of pits

None accepted.

Demarcation

If 5% of the total area when visually inspected and Ra Is met

Grit lines

If Ra is met.

Nicks (per tube length)

If depth < 0.010 in.

Oxides

Not accepted.

Pits

If dia < 0.020 in. and bottom is shiny.

Porosity

if dia < 0.010 in. and bottom is shiny.

Scratches

It length < 0.25 in., depth < 0.003 in., and Ra is met.

Surface cracks

None accepted.

Surface inclusion

If Ra is met and there is no liquid penetrant indication.

Surface residuals

None accepted.

Surface roughness (Ra)

See Table SF-6.

Water stains

If not deposits.

Weld dross

None accepted.

Table SF-6 Ra Readings for Valves
Mechanically Polished

Ra Average
[Note (1)] Ra Max

Surface
Designation µ-in µm µ-in µm

SVF1 15 0.375 20 0.5

SVF2 20 0.5 25 0.625

SVF3 25 0.625 30 0.75

Mechanically Polished and Electropolished

	Ra Average [Note (1)]		Ra Max
Surface Designation	µ-in	µm	µ-in	µm

SVF4	10	0.25	15	0.375
SVF5	15	0.375	20	0.5
SVF6	20	0.5	25	0.625

General Note:
All Ra readings are taken across the grain.

Note:
(1) The average Ra is derived from two readings taken at different locations. Other Ra readings are available if agreed upon between vendor and owner/user.
* Table SF-5-6 from ASME/BPE-1997

Conversion Chart
Standard Grit	Ra		RMS
Standard Grit	µ-in	µm	µ-in	µm
150g	27-32	.68-.80	30-35	.76-.89
180g	18-23	.46-.58	20-25	.51-.64
240g	14-18	.34-.46	15-20	.38-.51
320g	8-10	.21-.25	9-11	.23-.28

Grit: Measures the number of scratches per linear inch of abrasive pad. Higher numbers indicate a smoother finish.

RMS: Defined as Root Mean Square roughness, this method measures a sample for peaks and valleys. Lower numbers indicate a smoother finish.

Ra: Known as the Arithmetic Mean, this measurement represents the average value of all peaks and valleys. Lower numbers indicate a smooth finish.

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