Product innovation: DLC graphite rings by KLINGER Bartsch
DLC graphite rings stand up to extreme friction, pressure, and temperatures. DLC stands for diamond-like carbon. Product innovation by KLINGER Bartsch.
KINGER Bartsch is pleased to introduce new DLC graphite rings, with all of the benefits of graphite rings and none of the flaws. DLC graphite rings stand up to extreme friction, pressure, and temperatures, making them suitable for use in harsh environments with little or no need for maintenance.
New DLC coating: high temperature tolerance, low adhesion
KLINGER Bartsch has developed innovative new DLC coated graphite rings seals, designed to prevent seal adhesion without compromising temperature tolerance. Like the graphite rings KLINGER Bartsch is already known for, DLC graphite rings are effective at an enormous temperature range: starting from absolute zero at minus 273° to 450° C.
DLC, or diamond-like carbon, is a carbon coating that shares the high hardness and low friction properties of diamond. This non-reactive coating prevents valve or substrate adhesion to the ring seal without chemically altering the seal itself. DLC’s inert nature and impermeability to most gas and liquid make it ideal for use in industries requiring tight chemical tolerance.
„The new DLC coating is probably the first coating in the world that completely retains the excellent properties of graphite seals.“
Martin Einfeldt, Managing Director of KLINGER Bartsch
As with all KLINGER products, the DLC graphite ring has been proven out through rigorous lab testing. Fifteen-month-long product trials showed adhesion-free results under high pressure conditions. Minimal material left behind was easily wiped away, without need for cleaning solution or component disassembly.
BEFORE: DLC-coated graphite ring previous to fitting it into the stuffing box of the valve; the shimmer in rainbow colors demonstrates the DLC coating.
AFTER: DLC-coated graphite ring after disassembly - after sitting in the test valve for 15 months with a common surface pressure and without actuation.
DLC rings are compatible with a wide variety of media and industry conditions. Any application that currently uses KLINGER graphite rings can be substituted with DLC graphite rings, giving the system the same durability and environmental resistance without seal adhesion (known as the stick-slip effect).
The inside of a stuffing box you can see where the DLC graphite ring sat for over a year. There is no graphite stray material or debris.
The stick-slip effect
Non-coated ring seals can adhere to steel, particularly stainless steel. Because ring seals often sit immobile for long periods of time, particularly in valves for water and sewage applications, they undergo persistent compression against the valve outer ring and stem. When the valve needs to be activated, the ring seal sticks to the valve components, requiring significant force to unstick. This “breakaway torque” required to push the valve into motion can be close to the upper limit of force the valve stem is designed to handle, creating risk of damage and down time for repair. Stray material, or caking, left behind after the ring seal has been unstuck must be removed, both to protect valve components and to prevent downstream contamination of the system.
Most efforts to combat the seal stick-slip effect have drawbacks. The use of lubricant introduces more chemical components into a system, which is disallowed in applications such as oxygen and consumables. A variety of coatings are available for layering over graphite ring seals, such as PTFE, plastics, polymers, and tungsten or copper paste. These coatings drastically decrease the temperature tolerance of the graphite ring seals, sometimes by as much as one-third.
Smooth opening of the test valve after 9 months - proof that the new DLC-coated graphite rings don’t stick to the valve’s stuffing box or stem.
Easy to store, durable, compatible with many media: the many advantages of KLINGER’s DLC graphite rings
With KLINGER’s DLC graphite rings, a compromise between temperature tolerance and valve adhesion is no longer necessary. Customers with extreme temperature applications can now find a robust ring seal that won’t stick when low-maintenance systems require service. The DLC graphite rings are suitable for all types of valves, whether ball or butterfly valves, and compatible with a wide variety of media and industry conditions. Because DLC graphite rings resist adhesion despite long term immobility, storage conditions will be less critical for DLC than for graphite rings. Overall, the stability of DLC graphite rings will lead to a longer shelf life for stocking and warehousing assembled components and fewer customer service calls.