Product Description Electro polishing (EP), also known as electrochemical polishing, anodic polishing, or electrolytic polishing is an electrochemical treatment performed on the metal surface to remove the impurities and microscopic imperfections. The process leaves a shiny, smooth, ultra-clean surface finish. A pure water washing EP 316L tube is an electro polished TP316L (Ni ≥ 12%) tube that undergoes an additional multi-stage rinsing process with 18 MΩ·cm ultra-pure (deionized) water immediately after electro polishing and passivation. This pure water washing step thoroughly removes residual electrolyte, dissolved metallic ions and chemical traces left on the tube surface by the EP process. It is essential because any residual ionic contamination can later leach into high-purity process fluids, initiate pitting or rouging in stainless steel systems, and compromise water-for-injection (WFI), purified water (PW) and other sanitary fluid quality in pharmaceutical and ultra-pure water applications. Why Pure Water Washing Matters

Electro polishing uses acid-based electrolytes. Without thorough pure water washing, residues would remain on the surface. Pure water washing provides:
✓  Removes residual electrolyte and acid traces after electro polishing
✓  Eliminates dissolved metallic ions (Fe, Cr, Ni) from the surface
✓  Prevents ionic contamination of high-purity process fluids
✓  Reduces the risk of pitting corrosion and rouging in service
✓  Improves the stability and passivity of the Cr-enriched surface layer
✓  Meets the cleanliness expectations of pharmaceutical PW / WFI systems

Application

Pure water washing EP 316L tubes are the preferred choice for sanitary and high-purity fluid systems where fluid purity must never be compromised:
Pharmaceutical & Biotechnology (PW / WFI Systems)
Ultra-Pure Water (UPW) Systems
Food & Beverage Processing
Medical Equipment
Semiconductor Industry High Purity Pipeline
Laboratory Pure Fluid Pipeline
Precision Instruments
Hydrogen Industry Chain (LP/MP/HP/UHP)

Product Detail

Parameter	Value
Product Name	Pure Water Washing Electro Polishing Tube (Pure Water Washing EP
Material	TP316L (Ni ≥ 12%）
Outside Diameter	1/4" ~ 1" (6.35mm ~ 25.4mm)
Wall Thickness	0.035" ~ 0.083" (0.89mm ~ 2.11mm)
EP Lines	10
Daily Output	2,000 m
Inner Roughness	Ra ≤ 0.2µm
Outer Roughness	Ra ≤ 0.6µm

Material Grade

Grade	UNS	ASTM	EN
304L	S30403	304L	1.4307
316L	S31603	316L	1.4404
2205	S31803	S31803	1.4462
Hastelloy C-22	N06022	N06022	2.4602

* TP316L (Ni ≥ 12%) is the primary material for EP tubes.

Production Standard

Standard	Description
ASTM A269	Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for General Service
ASTM A270	Seamless and Welded Austenitic Stainless Steel Sanitary Tubing
ASTM B912	Standard Specification for Passivation of Stainless Steels Using Electropolishing

Process

Surface Preparation (Acid Cleaning) → Electro Polishing → Surface Passivation → Pure Water Treatment → Hot Nitrogen Drying → Clean Room Packaging
EP tube is derived from BA (bright annealing) pipe through electrochemical polishing, following ASTM B912 standard. In this product line, the pure water treatment step is performed as a multi-stage 18 MΩ·cm ultra-pure water rinse to guarantee the complete removal of ionic residues.

Dimension Tolerance

Outside Diameter (OD)	Tolerance OD (mm)	Tolerance WT (%)
1/4" ~ 1"	±0.1	±10

Nominal Length: 6 meters / each, or customized.
If higher outside diameter tolerance is required, welcome to contact us.

Roughness

EP Roughness:
✓  Inner: Ra ≤ 0.2 µm
✓  Outer: Ra ≤ 0.6 µm
Lower roughness (e.g. Ra ≤ 0.13 µm inner) is available upon request.

Specification / Size Sheet

Standard length is 6 meters. Custom lengths are available upon request.

Outside Diameter (OD)		Wall Thickness (WT)		Unit Weight
Inch	mm	Inch	mm	kg/m
1/4	6.35	0.035	0.89	0.12
		0.049	1.24	0.16
3/8	9.53	0.035	0.89	0.19
		0.049	1.24	0.26
		0.065	1.65	0.33
1/2	12.7	0.035	0.89	0.26
		0.049	1.24	0.36
		0.065	1.65	0.46
3/4	19.05	0.049	1.24	0.55
		0.065	1.65	0.72
		0.083	2.11	0.90
		0.095	2.41	1.01
		0.105	2.67	1.10
1	25.4	0.065	1.65	0.98
		0.083	2.11	1.23

Final Inspection

OD & WT, Length, Straightness, inner & outer surface roughness and endoscopy.
Chemical Composition
Spectrum analysis.
Mechanical Test
Tensile, Yield, Elongation (%), Hardness (HRB)
NDT (Non-Destructive Testing)
ET (Eddy Current testing).
PMI (Positive Material Identification)
Direct-reading spectrometer.
Marking and Color Coding
Marking and color coding available if required.
Optional Tests (Upon Customer Request)
According to customer requirements, the following additional tests can be performed on the sample(s):
✓  Chromium-iron ratio (Cr/Fe) and chromium oxide / iron oxide ratio
✓  Surface adsorption contamination
✓  Oxide layer thickness
✓  Surface defects
✓  Surface contamination
✓  Surface roughness
✓  Pitting temperature (CPT) test

Packing

EP tubing is ultrasonically cleaned then purged and dried with ultra high purity hot nitrogen before packing in the cleanroom. Each tube is end capped and bagged in double polyethylene bags to ensure the product's cleanliness. Finally the tubes are placed in wooden boxes for maximum protection during shipment.
1. Ultrasonic Cleaning — Tubes are ultrasonically cleaned to remove any residual particles.
2. Nitrogen Purge & Dry — Purged and dried with ultra high purity hot nitrogen.
3. Cleanroom Packaging — End capped, double-bagged in polyethylene, placed in wooden boxes.