How Rust can Affect a Solenoid Valve?

rusted-solenoid-valve

The “wetted” components of a solenoid valve are those that come in contact with fluid or gas media flowing through the valve.  Depending on the exact valve type, the most prevalent wetted components are usually the valve body, bonnet construction, gaskets, pistons, disks, plungers, and springs.

Checking Wetted Components of Solenoid Valve

It is prudent to check the compatibility of wetted components for the particular fluids and gases that will be flowing through the valve.  Failure to do so could result in component lockup due to rust, disintegrated o-rings and gaskets that inhibit operation or allow external leakage, shortened life of the critical sealing interface where the disk meets the valve orifice, cracked springs, etc.   

Stainless steel components that are not passivated to remove surface iron can exhibit small amounts of discoloration due to rust.  In most cases, this is an aesthetic issue.  The coloration will eventually wash away from the internals.  Exterior surfaces can be wipe down to remove.

How the valve can get contaminated

If rust on stainless steel is heavy or is pitting, there is an obviously an issue beyond surface iron.  The stainless steel may have been contaminated by foreign material during machining, polishing, and grinding processes.  For example, if a grind wheel was used on AISI 1020 steel, and then soon afterward on 430 stainless steel plungers without first cleaning or dressing that wheel.  The carbon steel can become embedded in the 430 stainless and create a surprising amount of damaging rust when positioned in resting water inside a solenoid valve.  Manufacturers must be cognizant of marine valve manufacturers and internal processes used to create such parts.

Rust in the form of iron oxide is a problem for solenoid valve if:

  • It breaks away and clogs small pilot orifices
  • Causes component lockup
  • Aesthetics are critical
  • Trace amounts of iron oxide cannot be picked up by the working fluid or gas

When selecting a solenoid, always review the compatibility of the wetted components and working fluid.