Common Materials and Selection Principles for Mechanical Seals
Mechanical seals are one of the precision mechanical basic components with relatively complex structures, and they are key parts in various types of pump equipment. For pumps and similar machinery, more than 50% of leakage problems are often caused by the mechanical seal.
Main material components of commonly used mechanical seals:
Common Materials for Mechanical Seals
Ambient and Condition | Rotating Seal Ring | Stationary Seal Ring |
Clean water, room temperature | 9Cr18 and 1Cr13 cobalt-chromium-tungsten surfacing, cast iron | Resin-impregnated graphite, bronze, phenolic plastics |
River water (containing sediment), room temperature | Tungsten carbide | Tungsten carbide |
Seawater, room temperature | Seawater, room temperature | Resin-impregnated graphite, tungsten carbide, cermet |
Superheated water 100 degrees | Tungsten carbide, 1Cr13, cobalt-chromium-tungsten surfacing, cast iron | Resin-impregnated graphite, tungsten carbide, cermet |
Gasoline, lubricating oil, liquid hydrocarbons, room temperature | Tungsten carbide, 1Cr13, cobalt-chromium-tungsten surfacing, cast iron | Resin-impregnated or tin-antimony alloy graphite, phenolic plastics |
Gasoline, lubricating oil, liquid hydrocarbons, 100 degrees Celsius | Tungsten carbide, 1Cr13, cobalt-chromium-tungsten overlay | Bronze or resin graphite impregnation |
Gasoline, lubricating oil, liquid hydrocarbons, containing particles | Tungsten carbide | Tungsten carbide |
Mechanical Seal Selection Method:
Depending on the operating conditions and the nature of the medium, mechanical seals are categorized into high-temperature resistant, low-temperature resistant, high-pressure resistant, corrosion-resistant, particle-resistant, and seals suitable for easily vaporized light hydrocarbon media, etc. Different structural types and materials of mechanical seals should be selected according to the specific application.
The main parameters for selection include:
- Seal chamber pressure (MPa)
- Fluid temperature (°C)
- Operating speed (m/s)
- Fluid characteristics
- Effective installation space for the seal
Basic Principles of Selection:
- Based on the seal chamber pressure, determine whether to use a balanced or unbalanced type, single-end face or double-end face structure, etc.
- Based on the operating speed, determine whether to use a rotating type or stationary type, hydrodynamic type or non-contact type.
- Based on the temperature and fluid properties, select the materials for the friction pair and auxiliary seals, and correctly choose the lubrication, flushing, heat preservation, cooling, and other mechanical seal circulation protection systems.
- Based on the effective installation space available, decide whether to use multiple springs, single spring, or wave spring, and whether to use an internally mounted or externally mounted design.