Specification of Carbon Steel Pipe
KNOW CARBON STEEL STEEL PIPES
In the industrial world, the use of pipes is very dominant. Among other things as a transportation system for various industrial products. Therefore the choice of material is very important considering the fluid to be flowed has different characteristics so that the media (pipe) will adjust.
A. Carbon Steel (Carbon Steel)
Steel is classified according to the chemical composition contained in it. Steel pipes and fittings are an alloy of iron (Fe) and carbon (C), and contain carbon less than 1.7%. Steel classification in three groups, namely: Carbon steel, low alloy steel and high alloy steel.
Carbon steel consists of iron, carbon less than 1.7%, manganese less than 1.65%, amount of silicon (Si), aluminum (Al), and contaminant limits such as sulfur (S), oxygen (O), nitrogen (N ), and there is no minimum limit specified for elements such as Al, Cr, Co, Ni, Mo, Ni [ASM, ASTM A 941].
Carbon steel is the most common pipe material in the power plant, chemical, process, hydrocarbon and industrial pipes industries. The specifications of carbon steel pipes commonly used in steam operation, water or air include ASTM A106 and ASTM A53. The common carbon steel for pipeline applications is the API 5L pipe. Mild steel is carbon steel with a carbon content of less than 0.30%. Medium carbon steel has 0.30% to 0.60% carbon. High carbon steel has carbon above 0.6%.
B. Alloy Steel (Alloy Steel)
Alloy steel is steel that contains a number of alloying elements,
such as 0.3% chromium (Cr), nickel 0.3% (Ni), molybdenum 0.08% (Mo), etc.
[ASTM A 941]. Low alloy steel is alloy steel containing less than the minimum percentage of alloy defined.
Alloy steel is commonly used in high temperature and high pressure operations such as in power plants, heat exchangers and furnace tubes, as well as chemical reactors. Examples of low alloy steels include 0.5Cr-0.5Mo (ASTM A P2 335), LCR-0.5Mo (ASTM A 335 P12), 1.5Cr-0.5Mo (ASTM PLL 335), 2Cr-MOL (ASTM A 335 P3B), 2.25 Cr-MOL (ASTM A 335 P22), 3Cr-MOL (ASTM A 335 P21). Medium alloy steel contains between 3% and 10% Cr, such as 4 to 9Cr - 0.5 for IMO (ASTM A 335 P5 to P9).
Each alloy element provides functions that are specific to improving the properties of its material properties:
- Carbon (C): increases strength (yield and ultimate) and violence.
- Manganese (Mn): as a deoxidizer and desulfurizer in alloy steel. Captures sulfur impurities, removes the fragile properties of iron sulfide, increases strength in the hot-work process. If the level of Mn / C> 3%, it will increase the toughness / toughness. Levels above 0.8% tend to give hardness to steel.
- Silicon (Si): as a deoxidizer that captures dissolved oxygen and avoids porosity. Increase castability.
- Chromium (Cr): increases resistance to abrasion and wear. Above 11.5% Cr will form a stable oxide layer. Cr also increases resistance to high temperatures.
- Molybdenum (Mo): increases the yield properties and strength against high temperatures.
- Nickel (Ni): causes a significant increase in toughness brittle and fatigue stress. Levels above 7% cause the atomic structure to become austenite at room temperature.
- Aluminum (Al): improves the deoxidation process when combined with Silicon.
- Copper (Cu): increases corrosion resistance.
- Vanadium (V): purifies steel ore, improves its mechanical properties. Increases resistance to hydrogenation at high temperatures.
The most common impurities in steel are sulfur and phosphorus. Sulfur (S) & Phosphorus (P) are impurities that form fragility, which will form iron-sulfide. Phosphorus (P)
