Carbon Steel Flange Types and Specifications

Carbon Steel Flange and end flange connectors are basically made of carbon steel. Common standards include ASTM A694, ASTM A105N (SA105N), MSS SP-44, DIN 2533. Accompanying pressure ratings are from class 150 to 2500.

Carbon steel is a steel with carbon content up to 2.1% by weight. Where in AISI defines: 

• No alloy element (minimum content) required, as of Cr, Mo, Ni, Ti, Va and etc.
• Specified minimum of Cu shall not exceed 0.04%.
• Maximum Mn 1.65%, Si 0.06%.

As carbon element content increases, the steel will become harder and stronger after heat treatment. On the contrary, it become less ductile. Where if without heat treatment, higher carbon will reduce weldability.

Carbon steel may include alloy steels in case it is not used as stainless steel.

Refers to Mild Steel or Low Carbon Steel Pipe Flanges

Carbon steel pipe flanges usually adopt mild steel or low carbon steel, as it includes small percentage of carbon, strong and tough but not readily tempered. Which with lower cost and material could be used for many applications.

• Low carbon steel: C content at 0.005% to 0.3%.
• Medium carbon steel: 0.3 to 0.8% of Carbon.
• High carbon steel: 0.8-2.0% of carbon.
• Ultra high carbon steel: 1.25% to 2.0% of C.

ASTM A105N (SA105N) Carbon Steel Pipe Flanges

ASTM  A105 steel grade is a typical common material (mild carbon steel) for forged carbon steel flange, it used in a lot of places for ambient and higher-temperature service in pressure systems. This material is durable, cost lower, and difficult to break. In case used in a stainless steel piping system it shall be adapted with a lap joint end ring.

Chemical composition of A105 carbon steel pipe flanges