“A question that we receive often is, “Industrial machine parts can be made with many different materials such as steel, copper, or plastics.  Why carbon?”.”

The core responsibilities of a plant engineer/ facility manager are planning, specifying, installing, modifying, and maintaining industrial facilities, systems, and equipment in order to achieve maximum availability and minimize costs.  For many industries, pumps are a major class of machines that consume large amounts of budget, manpower, and time for trouble-free operation.  Therefore, when a pump needs replacement parts such as mechanical seals, most engineers choose the pump’s original equipment manufacturer (OEM) as the primary supplier for the parts.  This is a simple and logical choice as the OEM parts would ensure to deliver the three key aspects of product quality: Performance, Reliability and Durability.


Performance is the product’s primary function. For mechanical seals, the performance can be measured by the ability to create a good seal without leakage.


Reliability is the probability that a product will not fail within a specific time period. This is a key element for users who cannot accept product failure before the next planned maintenance period.


Durability measures the length of a product’s life. A longer life of the mechanical seal contributes to lower pump maintenance costs and higher availability.

Common problems:

  • An unexpected pump failure caused an urgent need for mechanical seals, but the OEM supplier cannot deliver in time.
  • Management mandates reduction of maintenance budget without impact on quality.
  • Recurring problem with a pump is causing major problems and modification is required.

Understanding the OEM supply chain

Some of the world leading pump manufacturers are Alfa Laval, Ebara, Grundfos, KSB, Sulzer, and Wilo. All pump manufacturers design, assembly, test, installation, and service of the pump as the complete assembly. Most pump manufacturers have in-house production of the pump casing, shaft, impeller, and other components, but do not produce mechanical seals. They purchase the mechanical seals from OEM mechanical seal manufacturers.

The world leading mechanical seal manufacturers are AESSEAL, Chesterton, EagleBurgmann, Flowserve, and John Crane. These major manufacturers have in-house production of the mechanical seal housing, springs, and other components, but do not produce carbon, silicon carbide, and tungsten carbide seal rings. They purchase the seal rings from OEM seal rings manufacturers.

A global leader of seal ring manufacturer is Schunk Carbon Technology. From its factory in Giessen, Germany, Schunk Carbon Technology designs, produces, and tests the highest quality carbon, silicon carbide, and composite seal rings for the world’s leading mechanical seal manufacturers. Schunk Carbon Technology also supplies carbon bearings and other components to the leading OEM pump manufacturers. To ensure seal ring product quality, Schunk has resources for materials development, performance and durability testing, and conformance to specifications.