Valves are particularly sensitive to corrosion as relatively small amounts of corrosion can lead to the inability to actuate them, seal and control flow which will eventually lead to an uncontrolled process or unexpected down time. The reason they are so sensitive is if you were to compare a valve versus a standard 2” pipe, a pipe could typically withstand several thousandths of an inch of corrosion without having much of an impact or even being noticed as having an effect on the process. However, if a valve were to corrode by a few thousandths of an inch, this valve would lose the ability shut off leak-free.
Although many valve coatings have been used historically, when dealing with extremely corrosive acids at elevated temperatures, the options are very limited. If PFA polymers or specialty alloys like Hastelloy C276 cannot withstand the pressures, temperatures or corrosive environments, like hydrochloric acid and sulfuric acid, then Ultra-Metal tantalum surfaces should be considered. The main advantages of a tantalum surface are as follows:
- Unmatched Corrosion Resistance – Tantalum’s corrosion resistance outperforms Hastelloy by many times.
- Availability – Many valve types and styles the Ultra-Metal tantalum surface could be applied to. This can be important as specialty metal option may take many months to procure.
- High Pressures – As tantalum is a metal, it could withstand high pressure where polymer liners cannot.
- Elevated Temperatures – Tantalum metal can work in environments up to 250C without issue (and higher in non-oxygenated atmospheres).
When considering specialty metals for corrosion sensitive equipment like valves there are always tradeoffs of typically price vs performance, however with the Ultra-Metal tantalum surfaces this tradeoff is minimized.
Consider the gain in corrosion performance, the costs and the benefit to your operation. You are likely to be surprised.