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Raw Material
The material of choice in the biotech and biopharmaceutical markets is 316L stainless steel because of its good weldability and inherent corrosion resistance. However, 316L may contain impurities in the form of trapped gases and non-metallic inclusiions. To prevent this from becoming a problem for our customer, we select only specific grades of 316L and purchase materials to our own specifications.

Cardinal UHP also produces high purity copper tubing and fittings as well as other materials such as 314SS, Hastelloy, AL6XN and Monel.
Prior to placing any material in production we test representative samples to determine their wall thickness, ovality, weldability and compatibility with our electropolishing process and desired RA finish.


Mechanical Polishing
Mechanical polishing uses abrasive materials to reduce surface irregularities. Although it smoothes the surface, sometimes mechanical polishing is not enough.

All fittings are chemically passivated after fabrication and mechanical polishing to restore the passive layer of the original base material. Depending upon the specification, fittings are also electropolished to further reduce surface roughness and improve corrosion resistance.


Electropolishing creates a smooth clean surface that enhances corrosion resistance and reduces bioburden in microscopic crevices. With our innovative and proprietary ALC-300 process, Cardinal UHP has greatly increased our ablility to deliver quality electropolished components for dependable performance.

The Cardinal UHP electropolishing system creates a leveling action so effective that the finished surface often has only one tenth the surface area of a mechanically or chemically polished surface. During the electropolishing process the wall thickness is carefully monitored, ensuring excellent weldability with all automatic welding equipment.

Our ALC-300 controller uses statistical process control to bring the electropolishing process into the twenty-first century. Every vital parameter is monitored and regulated with this innovative computer controlled system. Since process parameters are stored in a database, the ulimate in material tracking is available.

Cleaning for bioPURE products is done with 18 meg ohm RO/DI water produced to the same standards used to clean integrated circuits. Cardinal's RO/DI system is monitored to the following purity:

  • Bacteria: Less than 6 colonies/100ml
  • TOC: Less than 25 ppb
  • Biltration: 0.1 micron absolute

Drying and purging is done with UHP nitrogen procured to the following, minimum purity specification:

  • Moisture: Less than 1 ppm
  • Oxygen: Less than 2 ppm
  • Total hydrocarbons: Less than 1 ppm 


Passivation dissolves free iron particles present following forming, macing, and electropolishing processes. This is accomplished by bathing the material in a heated solution of nitric acid. If these particles are allowed to remain trhy can attach themselves to the base material, eventually oxidizing and contamination your system.

When used in conjunction with our proven electopolishing process, passivation improves upon the original corrosion resitance of the alloy. Material performance is dramatically improved by the formation of a thick chromium enriched oxide layer.


Research and Development
As part of our extensive ongoing research and development programs Cardinal UHP has funded metallurgy research at the University of Missouri’s Center for Materials Research. Surface treatment studies have focused on developing increased standardization in the electropolishing process in order to achieve a more predictable and consistent finished product. Two areas that have been targeted to date are the variables involved in the process and the effect that raw materials have on the final product.The knowledge gained through our R&D efforts led to the creation of the first ALC-300 digitally controlled electropolish process monitoring equipment. This equipment is capable of producing consistent quality products without variance from operator to operator. Through our research, we have come to understand that many inconsistencies in the final product are directly attributed to variation in the microchemistry and grain size of the raw material. This is why we take special care to procure only materials providing optimal conditions for electropolishing.Today we have improved on the industrial specifications for raw stainless steel alloy, establishing our own proprietary standards for material procurement. Our continuing investigation of the effects of process variables allows Cardinal UHP to transform the art of electropolishing into a controlled science.


Quality Assurance
Cardinal UHP tubing and fittings are manufactured to meet or exceed ASME UHP standards. Cardinal UHP was the first company in the high purity tubing and fitting industry to be registered to international ISO 9001 standards. Our unyielding commitment to quality is evident in every step of our manufacturing process. From the start of procurement we specify stringent material standards. When raw materials arrive at our loading dock they are quarantined until wall thickness, ovality, smoothness, surface morphology, and chemical composition have been verified to insure it will meet our rigorous electropolishing procedures.All measuring instruments and analytical equipment are calibrated and traceable to NIST standards. Finally, every employee is empowered to declare piping and fittings unfit for sale if deviations from our standards are discovered.

Fittings and tubing are not only inspected visually, but stylus measurement devices and mass spectrometer helium leakdetectors are utilized. Additionally, the following quality assurance options are available:

  • Scanning Electron Microscope (SEM) photographs
  • Auger Electron Spectroscopy (AES) tests
  • Electron Spectroscopy Chemical Analysis (ESCA) tests
  • Testing for presence of moisture utilizing a Meeco Aquamatic Plus moisture analyzer
  • Scanning Tunneling Microscope (STM) surface analysis tests
  • Testing for presence of particles down to 0.01 micron utilizing a MET1CNC particle counter
  • Certification for oxygen and medical gas
  • Image processing (video probe and/or boroscoping capabilities)


Packaging is provided to protect the OD as well as the ID of the products. Protective caps and bagging is done to ensure the product arrives at your site in the same excellent condition it left our factory. Tubing can be ordered with ends faced, ready for welding.