Flange sealing surface: convex, male and female surface?

What the original poster is referring to are probably male flanges and female flanges, right? The convex surface was used in the old standards, but it has now been replaced by a convex profile; for details, refer to GB/T 9113.1-2000 on flat and convex profile integral steel pipe flanges

I don’t have GB/T 9113.1-2000; I just want to know in what types of invoices they are used respectively

A convex flange, also known as a bulged flange, has identical sealing surfaces on both flanges, along with a protrusion of 2-3 mm; it is generally used for pressures below 64 kg/cm2； Raised and recessed face flanges: one sealing surface is raised while the other is recessed; these two surfaces are used together and are generally employed in high-pressure applications.

A raised face (RF) surface is a smooth plane that can also have fine grooves machined into it. The sealing surface has a simple structure, is easy to machine, and facilitates the application of anti-corrosion linings. However, this type of sealing face gasket has a large contact area, and it tends to be pushed to the sides during pre-tightening, making it difficult to compress properly ； The MFM sealing surface is composed of a convex surface and a concave surface; a gasket is placed on the concave surface to prevent it from being pushed out, making it suitable for applications with high pressure and stringent sealing requirements. The tenon-groove surface (TG) sealing surface is composed of a tenon and a groove; the gasket is placed in the groove and will not be displaced. The gasket can be narrower, so the bolt force required to compress it is correspondingly smaller. Even in areas with high pressure, the bolt size does not have to be excessive. Therefore, it achieves a better sealing effect than both of the aforementioned sealing surfaces. The disadvantage of the sealing surface is that its structure and manufacturing are relatively complex, and it is difficult to replace the gasket packed in the groove. Furthermore, the tenon surface is prone to damage, so care should be taken during disassembly, assembly, or transportation. The tenon-and-socket sealing surface is suitable for flammable, explosive, toxic media as well as high-pressure applications. When the pressure is not high, it can achieve good sealing even with a larger diameter. Full-face (FF) and ring joint (RJ) full-face sealing are suitable for applications with lower pressures (PN1.6 MPa); ring joint connections are primarily used on necked weld flanges and integral flanges, with a pressure range of (6.3 MPa to PN25.0 MPa). (Figures (d) and (e)) For the sealing of high-pressure vessels and high-pressure pipelines with other types of sealing surfaces, conical sealing surfaces or trapezoidal groove sealing surfaces can be used; these work in conjunction with spherical metal gaskets (lens gaskets) and metal gaskets with oval or octagonal cross-sections, respectively. Sealing surfaces can be used in applications with high pressure, but they require high dimensional accuracy and surface finish, making them difficult to manufacture. Flange standard number, pressure class of the sealing surface PN, MPa; flange type and form of the sealing surface: Flange, standard number, sealing surface, pressure class PN, MPa. Flange type and seal surface configuration: Flange standard number, seal surface pressure class PN in MPa. Common flange type codes for valves: Plate type – flat welding PLHG20593, JB/T81-94, GB/T9119-2000; Raised face RF – 0.25 to 2.5. Flat welding flanges with raised faces are commonly used and can be paired with various low- and medium-pressure valve types such as gate valves, globe valves, ball valves, etc. Full flat face FF – 0.25 to 1.6; Welded neck flat welding SOHG20594, GB/T9116-2000; Raised face RF – 0.6 to 4.0. Welded neck flanges with raised faces are a structure that has been introduced in recent years and are widely used in petrochemical plants. Ribbed face MFM – 1.0 to 4.0; Tenon groove face TG – 1.0 to 4.0; Full flat face FF – 0.6 to 1.6; Welded neck butt welding WNHG20595, JB/T82-94, GH/T9115-2000; Raised face RF – 1.0 to 25.0. Valves with PN4.0–PN10.0 MPa usually use pipe flanges with raised faces, such as Z41H-40, J41H-64, H44H-100, etc. For pressures above 160 MPa, ring-type joint surfaces are used, such as J41H-160. Butt welding flanges can also be used with butterfly valves and check valves that employ clamp-type connections. Rough-faced MFM1.0～16.0, tenon-faced TG1.0～16.0, ring-connected RJ6.3～25.0, fully flat FF1.0～1.6; integral flange IFHG20596, JB/T79-94, GB/T9113-2000. Raised face RF0.6～25.0: For integral flanges on valves, those with PN≤2.5 generally have a raised face, those with PN≥4.0 have a rough face, and those with PN≥16.0 use a ring-connected design; however, some manufacturers use a ring-connected design for PN10.0 MPa valves and a rough face for PN16.0 MPa valves. Note that ammonia valves with PN2.5 MPa use a rough face (FM) and require pipe flanges with a raised face. Rough-faced MFM1.0～16.0, tenon-faced TG1.0～16.0, ring-connected RJ0.6～25.0, fully flat FF1.0～1.6; socket weld SWHG20597, GB/T9114-2000. Raised face RF1.0～10.0: This is the structural design commonly used in petroleum processing units introduced in recent years. The ribbed surface MFM1.0～10.0, the tenon groove surface TG1.0～10.0, and threads as well as flanges of type ThHG20598 and GB/T9114-2000 are commonly used in engineering construction; they are easy to install as welding is not required, and they are suitable for diameters ranging from DN10 to DN150. The raised surface RF0.6～4.0 is also frequently used in such applications. Full-flat FF0.6～1.6 butt-welded ring loose sleeve PJ/SEHG20599, JB/T84-94, GB/T9120-2000; raised-face RF0.6～4.0 suitable for pipeline systems exposed to corrosive media. Sewel welding: Ring loose sleeve PJ/RJHG20600, JB/T83-94, GB/T9121-2000; raised surface RF0.6～1.6, uneven surface MFM1.0～1.6, tenon groove surface TG1.0～1.6; flange cover BLHG20601, JB/T84-94, GB/T9123-2000; raised surface RF0.25～25.0 – used for pipe ends or as end caps. Concave-convex surface: MFM 1.0–16.0; Tenon groove surface: TG 1.0–16.0; Ring joint surface: RJ 6.3–25.0; Fully flat surface: FF 0.25–1.6; Liner flange cover: BL (S) HG20602; Convex surface: RF 0.6–4.0. This design was developed to save expensive heavy metal materials such as stainless steel. Convex surface: M 1.0–4.0; Tenon surface: T 1.0–4.0. Standard American design with butt welding: SOHG20616; Standard American convex surface: RF 2.0–26.0; Valves meeting PN2.5–5.0 standards, equipped with standard American fittings. Butt welding with flange: WNHG20617; Standard American convex surface: RF 2.0–42.0. Convex surfaces are used for pressures generally up to PN≤11.0 MPa, while ring joint surfaces are used for pressures of PN≥15.0 MPa. Ring connection surface RJ2.0～11.0

In the field of instrumentation, convex surfaces are used in most cases; concave-convex surfaces are used in some instances, while RJ surfaces are used when the pressure exceeds 11.0 MPa.

A convex flange, also known as a bulged flange, has identical sealing surfaces on both flanges, along with a protrusion of 2-3 mm; it is generally used for pressures below 64 kg/cm2； Raised and recessed face flanges: one sealing surface is raised while the other is recessed; these two surfaces are used together and are generally employed in high-pressure applications. It’s just that raised and recessed face flanges have very strict requirements regarding gaskets during installation :)

So, for the valve sealing surface that corresponds to the tenon-and-socket face flange, is it a tenon surface or a socket surface?

We use RF butt welding; there is no contact with gas: L

I agree with the view from the 5th floor, but nowadays RF flanges are being used