HG 20628-1997 Polytetrafluoroethylene coated gaskets for steel pipe flanges (American system) HG20628-1997 standard download decompression password: www.bzxz.net

Polytetrafluoroethylene coated gaskets for steel pipe flanges (American system)
HG20628-97
1. Subject content and scope of application
This standard specifies the type, size and technical requirements of polytetrafluoroethylene coated gaskets for steel pipe flanges (American system). This standard is applicable to polytetrafluoroethylene coated gaskets for raised face steel pipe flanges with a common tensile strength HN of 2.0MPa (Clas150) 5.0MPa (Cla8%300) and a working temperature of ≤150℃t as specified in HG20615. Note: If there is experience in use, it can be used up to 200℃. 429
GB3985
GB7136
GB/T13404||tt ||HG20615
《Asbestos Rubber Sheet》
Reference Standards
《General-purpose molded polytetrafluoroethylene resin》《Polytetrafluoroethylene coated gasket for pipe flange》《Types and parameters of steel pipe flanges (American system)》Gasket types and sizes
3.0.I The types of heat exchangers are divided into machined wing type, machined rectangle type and folded type according to the processing method, which are represented by PMF type, PMS type and PFT type respectively, as shown in Figure 3.0.1 3..2 Heat exchanger size
PMF type gasket size is specified in Table 3.0.2-1 PMS type gasket size is specified in Table 3.0.2-2. PFT type full sheet size F is specified in Table 3.0.2-3. 431
a. Machined wing type (PMF)
b. Machined square type (PMS)
C. Folded package type (PFT)
Gasket type
Figure 3.0.1 No.
Nominal diameter
Table 3.0.2-1
Coating layer
PMF type gasket size
Nominal pressure PN,MPa(Class)
(Class 150)
(Clagg 300)
Gasket outer diameter DA
Note, embedded inner diameter I: ·Medium/determined according to the whole piece type and embedded layer material properties. Table 3. 0. 2 ~ 2 wwW.bzxz.Net
Nominal diameter
Covering layer
PMS type gasket size
Covering layer
Nominal pressurePNMPaClags)
(Class E0)
(Class 300)
Gasket outer diameter D4
Note: The inner diameter D of the embedded layer is determined according to the whole piece type and the properties of the embedded layer material. 52.5
Nominal diameter
Capsule 3. 023
PFT type gasket size
Coating layer
Nominal pressure JPN, MPa(Clas）
(cla5s 150)
(Clas 3n)
Gasket outer diameter D
Note: The inner diameter D of the embedded material shall be determined by the manufacturer according to the gasket type and the performance points of the embedded material. 434
Technical requirements
The raw materials of the polytetrafluoroethylene coating layer shall comply with the provisions of GB7136PTFESM031 for grade 1. 4 1
4.0.2 The embedded layer is asbestos rubber sheet, and its technical performance indicators shall comply with the provisions of XB350 or XB450 in GB3985. If the purchaser has special requirements, other suitable materials may also be used, but they should be indicated when ordering. 4.0.3 The limit deviations of the inner diameter D: and the outer diameters D, and D, of the gasket shall be in accordance with the provisions of Table 4.0.3. The limit deviation of the coating thickness is ±0.05mm, and the limit deviation of the total thickness of the gasket is ±0.10mm. The surface of the coating should be flat, smooth, without warping and deformation, with uniform thickness and no defects such as holes and clips. 4.04
The compression rate, elasticity, stress relaxation rate and sealing leakage rate of the gasket shall comply with the provisions of GB/T13404. 4.05
4.0.3 Limit deviation of gasket inner diameter D, and outer diameter Ds, D, Nominal diameter
Limit deviation
Limit deviation
Extreme deviation
5 Marking and packaging
5.0.1 Gaskets shall be packaged according to type, specification and material, and a product quality inspection certificate shall be attached upon delivery. Gaskets shall be labeled with the inner diameter specified in 5.0.2. 5.0.2 Marking example
Machine-processed wing-type polytetrafluoroethylene gasket for raised-face steel pipe flange with nominal diameter of 100mm and nominal pressure of 5.0MFa (Class 300) is marked as:
HG 20628
PTFE coated gasket
Folded polytetrafluoroethylene gasket for raised-face steel pipe cover with nominal diameter of 500mm and nominal pressure of 2.MPa (Class 150), the embedded layer material is rubber sheet, and it is marked as: HIG 20628
PTFE coated gasket (rubber sheet)
Additional instructions: Proposer, editor and main drafter of this standard Proposer: Chemical Process Piping Design Technology Center Station, Ministry of Chemical Industry Equipment Design Technology Center Station, Ministry of Chemical Industry
Editor; Equipment Design Technology Center Station, Ministry of Chemical Industry Main drafters: Ying Daoyan Yu Jun
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