about REDOX
System Cleanliness I
System Cleanliness II
System Cleanliness III
System Cleanliness IV
Safe Working Pressure Using ASME
A106 Grade C Pipe
Contacting REDOX


To easily understand standards simply look for the operative words. In every standard these words provide clarity of action. Examples of these are: shall, will, and properly. The base standard for piping a hydraulic system is ASTM D4174 Section It states "All pipe and tubing shall be properly cleaned and preserved". The words"shall be properly" require that the cleaning and preservation not only be appropriate and adequate but that it will also enhance every other phase of fabrication and system operation. Additionally, this also includes the selection and procurement of pipes and tubes that demonstrate good bending, welding and the capability to withstand without rupture the pressures seen by the system.

Steel wants to attract electrons to become stable. That is what the +2 means next to the Fe on the periodic chart. This is called reduction. REDOX uses a reduction process that provides the extra electrons to stabilize the pipe in the cleaning process. Pickling removes the scale by stripping away electrons. This process is called oxidation. As seen in Figure 1 this process is only marginal at removing scale. Additionally, oxidation activates the metal and makes it very susceptible to rust. See Figure 2.

about REDOX

Figure 1. Electron Microscope - Scale

about REDOX

Figure 2. Pickled Pipe - Rust


The preservation of REDOX pipes uses a vapor space inhibiting (VSI) oil as called out in ASTM D4174. This oil is hydrophobic which means it will lift water out of the grain of the metal as well as providing a continuous rust protection through emission of rust inhibiting vapors on the I.D. of the pipe.

Pickled and oiled pipe uses a heavy AW46 type oil that is hydrophilic which means that it will absorb water and be a source of rust on the I.D of the pipe. Additionally, this oil has none of the rust fighting vapors of a VSI oil. The traces of water left in the grain of the metal will form electrolytes with the chemical residues from the neutralization phase of pickling. The trace iron chloride (dissolved scale) in the rinse reacts with the sodium nitrite in the neutralization tank to form NaCl, ordinary table salt. This leads to system killing rust.

By adhering to these standard, REDOX is able to lower the cost of fabrication greater than the total price of the pipe including shipping, while simultaneously providing more uptime profit for the user of the system. A few of the many benefits of using pipe that meets these standards are:

  • Corrosion free pipe
  • Scale resistant welding
  • Faster flushing
  • Easier to paint
  • Better laminar flow
  • Better bending
  • Easier handling
  • Better welds
  • Higher operating pressure capability
  • Reduced energy consumption
  • Lower maintenance cost
  • More uptime
  • All phases of piping will be explored through this series of articles. This knowledge will allow you to not only build better systems but also to communicate effectively to win more jobs.

    If you have questions...feel free to contact us. REDOX has for thirty five years consistently delivered high quality products by following standards.

    For more information call 800.421.3369 or email


    REDOX, Inc.
    7800 7th Ave. S
    Seattle, WA 98108 USA
    (800) 421-3369

    © 2011 REDOX, Inc.