Spiral-Wound Gaskets
(1) Applicable Scope of the Spiral-Wound Gasket
According to the petrochemical industry standard SH 3407-2013, spiral-wound gaskets are suitable for the following conditions:
Nominal pressure range: PN 1.0–25.0 MPa
Temperature range:
Stainless steel strips with special asbestos filler: –50 to 500 °C
Stainless steel strips with flexible graphite filler: –196 to 800 °C (≤ 600 °C for oxidizing media)
Stainless steel strips with PTFE filler: –196 to 200 °C
The chemical industry standard HG 20160-2009 specifies the following:
Nominal pressure range: PN 1.6–16.0 MPa
Temperature limits:
Stainless steel with asbestos filler: Max. 500 °C
Stainless steel with flexible graphite filler: Max. 650 °C (≤ 450 °C for oxidizing media)
Stainless steel with PTFE filler: Max. 200 °C
(2) Material Requirements
The hardness of the metal strip should be HV ≤ 150.
For austenitic stainless steel flange sealing, the chloride ion content in the non-metallic filler must be ≤ 100 ppm.
(3) Selection Based on Flange Type
Flat and convex flanges: Use spiral-wound gaskets with inner + outer rings or outer rings only.
Male-and-female flanges: Use spiral-wound gaskets with inner rings only.
(4) Pressure Suitability
Spiral-wound gaskets are generally recommended for medium- to high-pressure flanges. On low-pressure flanges, insufficient bolt force may compromise sealing performance. Expanded graphite spiral-wound gaskets are preferred for such applications.
(5) Inner Ring Material Requirements
The inner ring material should have equal or superior corrosion resistance compared to the metal strip.
Stainless steel must comply with GB/T 3280 or GB/T 4237.
Carbon steel (middle ring) should meet GB/T 11253 or GB/T 912, with surface treatments such as spraying or electroplating unless otherwise specified.
(6) Basic Type Specifications
Spiral-wound gaskets are primarily used for tongue-and-groove flanges.
Class 600, 900, 1500, 2500 gaskets and those with PTFE filler must include an inner ring.
Flexible Graphite Composite Gaskets
Max. working pressure: 6.3 MPa
Max. temperature:
Low-carbon steel core: 450 °C
Stainless steel core: 650 °C (450 °C for oxidizing media)
Compatible media:
Liquids: Water, oils, solvents, acids, liquid hydrocarbons, cryogenic liquefied gases.
Gases: Air, hydrogen, hydrocarbons, steam, flue gas, and highly permeable gases.
Advantages:
Low flange surface finish requirements.
Suitable for corrosive, low-pressure, high-temperature applications.
Ideal replacement for asbestos-rubber sheets in general-parameter scenarios.
Serrated Composite Gaskets
Operating range: –200 °C to +700 °C, vacuum to 25 MPa.
Features:
Maintains sealing under low compressive stress.
Suitable for DN10 pipe flanges to DN2500 vessel flanges.
Performs well in fluctuating temperature/pressure conditions.
Metal-Clad Gaskets
Max. temperature: 450 °C
Max. pressure: 6.4 MPa
Hardness limits (HB):
L2: <40
08 steel, tin-plated steel: <90
0Cr13: <183
0Cr19Ni9, 0Cr18Ni11Ti, 00Cr17Ni14Mo2: <187
Asbestos filler boards must not be spliced (must be specified in procurement orders).
Metal Gaskets
(1) Metal Ring Gaskets
Applications: High-pressure, high-temperature flanges.
Standards:
National/petrochemical standards: PN 2.0–42.0 MPa
Chemical industry standard: PN 2.5–16.0 MPa
JB/T 89-94: 6.3, 10, 16, 20 MPa
Material hardness: HB 30–40 lower than the flange sealing surface.
Surface finish: ≤ Ra 1.6 μm (no scratches, cracks, or defects).
Anti-corrosion: 10 or 08 steel gaskets must be oil-coated post-inspection.
(2) Metal Tooth Gaskets
Applications: Male-and-female or butt-weld flanges (PN 4.0–16.0 MPa).
Max. temperatures:
08/10/022Cr17Ni12Mo2: 450 °C
0Cr13: 540 °C
06Cr19Ni9: 600 °C
Dimensional tolerances:
Parallelism deviation: ≤ ±0.05 mm per 100 mm diameter.
Tooth surface roughness: Ra 1.6 μm.
Fabrication: Must be single-piece (no welding allowed).
