When purchasing flanges, valves, etc., should casting or forging be chosen?

The mating flanges are only available in forged form, while valves are generally produced in bulk or, for larger diameters, in cast form, as this is cheaper; as long as the wall thickness meets the pressure requirements, it’s sufficient. For some applications that are non-standard or subject to high pressures, forgings are required.

Forged parts are considerably more expensive than cast ones, but they possess better mechanical properties. Manufacturers will produce cast parts as long as there is no specific requirement for forged ones. During forging, the metal undergoes plastic deformation, which helps to refine its grain structure. Forged parts are commonly used in the production of critical components; they are formed at high temperatures using methods such as extrusion or hammering, so that the metal in its plastic state takes on a specific shape and size, thereby changing its physical properties. Casting is a type of metal hot working process that requires the material to have good properties. It enables the production of parts with complex shapes, and is often used for the rough fabrication of components where high mechanical properties are not required. During this process, the metal is heated until it melts, and then poured into sand molds or dies; once cooled, it solidifies to form the desired object

The third floor explained it in quite detail. On the second floor, what was said isn’t wrong either. Just to add, flanges are also available in cast form, which are generally used in low and medium pressure applications. In fact, cast flanges are relatively rare, as they have significant defects, especially in terms of their microstructure. If castings are produced in bulk, the price will be lower; they are cast in one go, eliminating the need for complex machining. There are also reasons related to welding.

Floors 2, 3, and 4 are all described in great detail. It mainly depends on design and working pressure considerations, as well as the medium and cost factors. For flanges in general, forgings are used. If the pressure is not high, cast iron valves are usually chosen for applications such as water treatment.

The simplest way to distinguish it with the naked eye is to look at the letters on the valve body: if the letters are raised, it is cast; if they were engraved using a laser or a marking machine, it is forged; and if the letters are recessed, it is also forged.

Valves are generally cast, unless otherwise specified.

Small-sized valves are generally forged, while large-sized valves are cast. To tell the difference, check the material certificate and the indication of the valve body material. There’s no need to worry about any of this anymore, because you no longer have the right to make choices regarding the factory; the design team will specify the procurement requirements in the pipeline material list. Of course, I’m referring to proper and compliant methods.

Casting and forging are both carried out according to the customer’s requirements; even in the absence of specific requests, pressure ratings must still be specified. It’s not that high-pressure grades cannot be used for casting – large-diameter gate valves made of WCB can also be designed to be self-sealing at 2500 LB pressure. It’s just that ball valves don’t have such a high value. Generally, valves with a diameter of 2 inches or less are made as forgings, while those with a diameter greater than 2 inches are cast. That’s the usual practice, but if you have the money, it’s also possible to have a 3-inch valve made as a forging! As for the appearance of the valves, the castings are rough; this is attributed to problems with the molds. When sand molds or wax molds are opened, if their quality is poor, the resulting blanks will have many defects. But castings simply cannot achieve the same appearance as forgings no matter what. Forgings are also divided into die forging and free forging; die forging is the preferred method for mass-producing forgings. By then, if you see those two things more often, it will be easier for you to tell them apart