12% Chromium Sucker Rod & Coupling for Corrosive & Deviated Applications
- Focus on increasing Chromium content and improving grain structure to combat Sulfide Stress Cracking
- Superior cycle life performance
- Long operating life
- Reduce downtime, improve production
- Rely on chemical treatment
- Frequent rod failure / work-overs
- Interrupted production operation
- Coated product offerings lack durability and can be damaged
After years of research and development, engineers at Exceed have found a special Chromium Alloy Steel and developed EH9 steel grade. This new product not only can withstand extreme corrosion, it also delivers ultra-high tensile and fatigue performance, making it the rod of choice for the toughest wells.
Inside EH9’s special alloy, abundant (~12%) Chromium atoms diffuse much faster than that in conventional Carbon alloys. In corrosive environments, a chromium-rich passivation layer forms on the grain boundary, effectively stopping the corrosion process at the material surface while protecting the integrity of the micro-structure inside.
Significantly reducing Carbon content (<0.03%) also eliminates the carbon-chromium compound precipitation along grain boundaries. This also improves the material’s abrasion performance; not only protecting itself, but all other material it comes in contact with.
Small amounts of Mo, Ni, Al added to the material act as an anodic process blocker; while Cr, Cu, Si, Mn and other rare earth metals promote a cathodic process and surface activity. As a result, these further improve its corrosion performance against acidic mediums including CO2, H2S and HCl and electrochemical corrosion.
Figure 1. Chromium-rich passivation layer form on grain boundaries
Figure 2. EH9 – Grain Structure (400X)
Figure 3. EH9 rod shows no visible corrosion after 280 days of operation
Figure 4. EH9 coupling (after 280 days) vs. T-coupling (after 180 days)