The high-pressure flange sealing surface of the high-pressure hydrogenation unit usually adopts RJ surface, and the gasket used is a metal ring gasket, which is divided into elliptical metal ring gasket (elliptical gasket) and octagonal metal ring gasket (octagonal gasket) according to the cross-sectional shape. Shanghai Xidi Pipe Fitting Co., Ltd. specializes in the production and sales of RJ high-pressure flange sealing metal ring gaskets, made of stainless steel and special steel, with reliable sealing, high temperature resistance, high pressure resistance, corrosion resistance, etc., suitable for connecting pipelines and equipment under various harsh working conditions.

On the conical surface of the groove, the octagonal pad is in surface contact (inclined surface), while the elliptical pad is in line contact (a line on a curved surface), both of which belong to metal elastic line contact sealing.

1、 Standard for metal ring gasket

The standards corresponding to metal ring gaskets for steel flanges include PN series (GB/T 9128.1-2023 Metal ring gaskets for steel pipe flanges Part 1: PN series) and Class system (GB/T 9128.2-2023 Metal ring gaskets for steel pipe flanges Part 2: Class series). The relevant requirements and marking methods are as follows:

1. Requirement:

(1) Metal ring pads should not be spliced together. The sealing surface of the metal ring gasket should not be welded.

(2) The sealing surface of the metal ring gasket should not have scratches, dents, cracks, or dents.

(3) The hardness of the metal ring gasket is generally lower than that of the flange to ensure a tight connection. Among them, the hardness of the octagonal pad should be selected as Brinell hardness, and the hardness of the elliptical pad should be selected as Rockwell hardness.

(4) Metal ring pads should be placed horizontally during storage and transportation.

2. Tag Example

(1) PN series: Octagonal gasket, nominal diameter DN100, nominal pressure PN63, metal ring gasket made of 316 material, marked as GRO GB/T 9128.1 DN 100 PN 63 316;

(2) Class series: Elliptical pad, nominal diameter DN100, nominal pressure class 150, ring number R36, metal ring pad made of 06Cr17Ni12Mo2 material, marked as:

GRV GB/T 9128.2 R36 316 or

GRV GB/T 9128.2 100-150 316。

Among them, the Class series has ring numbers.

2、 Installation requirements for metal ring gasket

In Article 8.1.4 of GB 50517-2010 Code for Acceptance of Construction Quality of Metal Pipeline Engineering in Petrochemical Industry (2023) and Article 7.2.3 of SH/T 3501-2021 Code for Construction and Acceptance of Steel Pipeline Engineering for Toxic and Combustible Media in Petrochemical Industry, the requirements are as follows:

Before assembling flange connections sealed with metal ring gaskets, a contact line inspection should be conducted between the sealing surface of the flange ring groove and the metal ring gasket. After the metal ring gasket rotates 45 ° on the sealing surface, check that there is no interruption in the contact wire, otherwise it should be ground and repaired.

Note: The sealing surface of the metal ring gasket should not have scratches, dents, cracks, or pits. The sealing surface of the metal ring gasket should not be welded, and PTFE tape should not be wrapped around the metal ring gasket.