Electro Polishing
The uncompromising high quality of ASFLOW EP products is a result of years of experience and accumulated know-how in the electro-polishing process during which ASFLOW has optimized the following four critical elements:
- The temperature of the electrolyte solution.
- The amplitude of the cathodes and their location relevant to the product.
- The level of acidity of the solution.
- The amount of the time that the part is immersed in the solution.
NOTE :
The ASME BPE guidelines are very clear, for example, that flash electro-polishing, i.e., immersion of the part in the electrolyte solution for a very short period of time, is unacceptable.
Schematic Set-up of EP System
As a result, ASFLOW EP products stand out from competing products in the following ways:
- A thicker EP layer to minimize rouging
- Higher Chrome concentration for better corrosion resistance
- Guaranteed smoothness (Ra) in all internal surfaces to reduce Bio film
Removal of Contaminants
ASFLOW EP removes the contaminants that were introduced by the various production processes. The unique EP process achieves a level of contaminant removal that exceeds the ASME BPE standard.
Superior Corrosion Resistance
During the electro-polishing process naturally occurring chrome in the product’s base metal is “pulled” to the surface. The thicker the chrome layer that forms on the product surface, the more resistant it will be to corrosion over time. It will also decrease rouging.
The highly optimized ASFLOW EP process ensures a particularly thick chrome layer – one of the reasons why ASFLOW EP fittings dominate the bio-pharma sector.
Standards
- ASTM A-269 / A270-S2
- ASME BPE
Surface Finish
Surface finish specifications are the same for fittings & tubes.
Please refer to table SF-2.4-1
Table SF-2.4.1-1 Ra Readings for Metallic Process Contact Surfaces
|
Surface Designation |
Mechanically Polished [Note (1)] | |
|---|---|---|
| Rα Max. | ||
| μin. | μm | |
| SF0 | No finish requirement | No finish requirement |
| SF1 | 20 |
0.51 |
| SF2 | 25 | 0.64 |
| SF3 | 30 | 0.76 |
| Electropolished | ||
| Rα Max. | ||
| μin. | μm | |
| SF4 | 15 | 0.38 |
| SF5 | 20 | 0.51 |
| SF6 | 25 | 0.64 |
|
Surface Finish Code |
BPE Surface Designation |
Inside Surface |
Outside Surface |
||
|---|---|---|---|---|---|
|
Ra Maximum |
Surface Condition |
Surface Condition |
|||
|
μ-in. |
μm |
||||
|
PL |
SF1 |
20 |
0.51 |
Mechanically Polished* |
Mechanically Polished |
|
PM |
SF4 |
15 |
0.38 |
Mechanically Polished* & Electro-polished |
Mechanically Polished |
* Or any other finishing method that meets the Ra max.
ASFLOW EP Exceeds the ASME BPE Quality Requirements
The table below shows how ASFLOW EP exceeds the ASME BPE quality requirements.
|
Attribute |
ASME BPE Recommendation |
ASFLOW Electro-polishing |
|---|---|---|
|
EP layer Thickness |
15Å < |
20Å < |
|
Cr/Fe ratio |
1 < |
1.5 < |