A material of construction for a particular fitting or part of a composite fitting like valve, steam traps etc. must be carefully chosen based on various factors like :

1. Fluid Nature : corrosiveness, toxicity, flammability, viscosity.
2. Service pressure and temperature.
3. Fluid nature : Corrosive, Food industry etc.
4. Fabrication method : Forging, casting and from plates.
5. Availability.
6. Environment (Desert, Temperate, Marine)
7. Price (Economy)

Lists of Piping Materials

Piping hardware generally includes Pipes, Fittings, Valves, Special Items like steam traps, strainers, filters etc. Here is a list of ASTM materials used for manufacturing of various piping parts.

Selection Criteria

1. Big bore flanged valves and components are mostly manufactured by Casting.
2. Small bore flanged valves, socket welded and threaded components are mostly forged.
3. Components like spectacle blind, Strainers etc. are made using plates.
4. Materials are selected based on their mechanical and metallurgical properties.
5. Mechanical properties: strength, ductility, hardness, brittleness, toughness
6. Metallurgical properties: Chemical composition, weldability.
7. Carbon increases strength of steel but decreases weldability.
8. Carbon steel used in piping has carbon content between 0.15% to 0.30%.

Various Categories of Steel

Based on the chemical compositions, Steel can be categorized into four basic groups:

1. Carbon Steel
2. Alloy Steel
3. Stainless Steel
4. Tool Steel