1、 National standard marking
The flange should be marked according to the nominal diameter, nominal pressure, sealing surface form code, steel pipe series code used (with metric pipe code "Series 2" and British pipe code not marked) and standard number.
Marking example: Raised face welded steel pipe flange with a nominal diameter of 80mm and a nominal pressure of 4.0MPa (25bar) (equipped with metric pipes)
Flange DN80-PN40 M (Series 2) GB/T9115.2-2000, raised face flat welded steel pipe flange with a nominal diameter of 100mm and a nominal pressure of 5.0MPa (25bar) (equipped with British pipes) DN100-PN50 RF GB/T9116.1-2000.
2、 Mechanical Department Standard Markings
Marking example: Raised face flat welded steel pipe flanges with a nominal diameter of 500mm and a nominal pressure of 1.6MPa, Series 2
Flange 500-16 JB/T81-94
Concave butt welded steel pipe flanges with a nominal diameter of 300mm and a nominal pressure of 6.4MPa, Series 1
Flange 300-64B (Series 1) JB/T82.2-94
(Note: The default outer diameter of pipes in the mechanical department standard is Series 2, and the classification of welding flanges is: A-type convex surface, B-type concave surface, C-type tenon surface, D-type groove surface)
3、 Standard marking of the Ministry of Chemical Industry
The flange should be marked according to the following regulations (this marking method is recommended)
a. Standard number: All types of pipe flanges are uniformly marked with the standard number of this standard: HG20592.
b. The flange type code shall be in accordance with the provisions of Table 5.0.1.
When threaded flanges use tapered pipe threads according to GB/T7306, they are marked as "Th (Rc)" or "Th (Rp)"
When using tapered pipe threads according to GB/T12716 for threaded flanges, it is marked as "Th (NPT)"
If the thread code is not marked on the threaded flange, it is Rp (GB/T7306.1).
c. Flange nominal diameter DN (mm) and applicable steel pipe outer diameter series:
Integral flange, flange cover, lined flange cover, threaded flange, and the markings applicable to the outer diameter series of steel pipes can be omitted;
Suitable for flanges of international standard series steel pipes (commonly known as British pipes), marked with "DN (A)"
Suitable for flanges of domestic series steel pipes (commonly known as metric pipes), marked as "DN (B)".
d. The nominal pressure of the flange is PN, MPa.
e. The form code of the sealing surface shall be in accordance with the provisions of Table 6.0.1. If the raised face flange is machined with a dense water line, it shall be marked as "RF (A)".
f. The wall thickness of the steel pipe should be provided by the user.
The wall thickness of the steel pipe should be marked on the neck welding flange and the loose sleeve flange of the welding ring.
g. Material grade.
h. Other. Adopt requirements or additional requirements that are inconsistent with the provisions of this standard series, such as the surface roughness of the sealing surface.
Product parameters
Raised face flat welded steel pipe flange with a nominal diameter of 1200mm and a nominal pressure of 0.6MPa, equipped with metric pipes, made of Q235A material
HG20592 flange PL1200 (B) -0.6 RF Q235A
Raised face necked flat welded steel pipe flange with a nominal diameter of 300mm and a nominal pressure of 2.5MPa, equipped with British pipes, made of 20 steel
HG20592 flange SO300 (A) -2.5 M 20
Nominal diameter 150mm, nominal pressure 16.0MPa, ring connection surface with British pipe, welded steel pipe flange with neck, material 16Mn, steel pipe wall thickness 10mm
HG20592 flange WN150 (A) -16.0 RJ S=10mm 16Mn
The nominal diameter is 200mm, the nominal pressure is 1.0MPa, and the raised face of the metric pipe is equipped with a welded ring loose sleeve steel pipe flange. The material is flange 20, welded ring 316, and the wall thickness of the steel pipe is 4mm
HG20592 flange PJ/SE200 (B) -1.0 RF S=4m 20/316