Carbon steel flanges are produced majorly included 3 techniques: casting, forging, cutting from steel plate and rolling from steel stripes.

Casting flange production process

The casting flange is made of iron filings.  After the iron filings is melted, the molten iron liquid is poured into the mold to form the desired shape, the flange shape is always round like a bread.  When the metal liquid has hardened, the flange mold opened and the casting is removed, then machined to the desired dimension flanges and sealing surface finish and then drilling the hole.

The flanges made by casting method has the advantage of high production efficiency and low production cost, they are very suitable for medium and low pressure pipelines.  However, the casting flange also have the obvious manufacturing defects, such as blowholes, cracks and have not very smooth internal organization streamline, it is not be suggested used on the high pressure projects.

Forging flange production process

The forging flange is made of steel billet, round bar or slabs.  Firstly, heating the metal in the heating furnace and then compressing the material with a power hammers, cooling and forming into semi-finish flanges after forging. The final step is machine and drilling them into the appropriate specification and dimensions according to the request of the customers.  

The forging process method are mainly consist free forging and die forging. 

Free forging productivity is low, the processing allowance is large, but the tool is simple, universal, so it is widely used to forge the shape of a simple single piece, small batch production of forgings. Free forging equipment includes air hammers, steam-air hammers and water presses, which are suitable for the production of small, medium and large forgings respectively. 

Die forging is highly productive, simple to operate and easy to mechanise and automate. High dimensional accuracy, small machining allowance and more reasonable fibre distribution of the forgings can further improve the service life of the parts.

Forging flanges generally have lower carbon content than the casting flanges and are not easy to rust. They have smooth streamline, uniform internal organization, and better mechanical performance than casting flanges. There are no defects, such as blowholes and cracks existing in the forging flanges. Furthermore, the raw material we used for our customer’s orders are are brand-new and purchased from qualified steel vendors or companies, we wish to establish long term business relationship with every valuable customer but not one-shot deal.

Cutting and rolling flange production process

Cutting process refers to producing flanges by directly cutting a round plate with the inner diameter, outer diameter and thickness which can be further processed later from the middle plate, and then processing the bolt hole and waterline. The maximum diameter of such flanges is limited by the width of the middle plate. 
rolling process refers to producing flanges by cutting stripes from the middle plate and then rolling them into round shape. This process is mainly used for the production of large flange. After the rolling process, weld and then flatten the round shape, and finally process the serrated spiral finish and bolt hole.

               Raw Material in stock                         Cutting Raw material by sawing machine                          Heating in Furnace

                     Compressing                                                               Forging                                                      Heat Treatment

                             Machining                                                      Drilling Holes                                     Removing the burr on the holes

          Final Inspection before shipment                                     Marking                                          Loading at yard of Tianjin Port