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Sealing series >> Half Metal Gaskets >> Metallic wrapping pad B

Metallic wrapping pad B

    The metal spirally-wound gasket adopts high-quality SUS304 or SUS316 ("V" or "W"shape) metal strips, other alloy materials and some flexible materials like graphite, asbestos, PTE and non-asbestos, which are overlapped and wound spirally with each other. The metal strips are fixed on the initial and terminal ends by means of spot welding. The metal spirally-wound gasket has the best resilien ce among the semi-metal hermetic gaskets. Its structural density can be made subject to different locking forces. Also the internal and external steel rings can be used to control its maximum compaction. It's not demanding for the surface precision of the flange sealing surface contacting the spirally-wound gasket. It's especially applicable for such occasions as uneven load, slack joint, periodical changes of temperature and pressure, impact or vibration. It's an ideal static seal element for flange connection in valves, pumps, heat exchangers, towers, manholes,handholes and so on.

Application scope of spirally-wound gasket
    Sealing of flange connection in pipelines, valves, pressure containers, condensers, heat exchangers, towers, manholes, handholes and so on in such industries as petroleum, chemical engineering, metallurgy, electricity, shipping and machinery.

Type of metallic wrapping pad
Type Section shape Code name Thickness(mm)
Basic wrapping pad   A 3.2 4.5
Wrapping pad with inner ring   B   4.5
Wrapping pad with outer ring   C   4.5
Wrapping pad with inner and outer rings   D   4.5

Structural material of metallic wrapping pad

Filling Steel band Inner ring Outer ring
Asbestos wrapping SUS 304 Carbon steel Carbon steel
Graphite wrapping SUS 316 SUS 304 SUS 304
Teflon wrapping SUS 316L SUS 316 SUS 316
    SUS 316L SUS 316L

Filling Temperature() Max operating pressure(kg/cm2)
Asbestos wrapping -200~550 250
Graphite wrapping -150~450 100
Teflon wrapping 240~260 100

The following table lists metallic materials for inner ring and wrapping:

Product name AISI Hardness(HB/HV) Temperature(C)
304 Stainless steel      304      130~180      -250~+550
316 Stainless steel 316 130~180 -100~+550
316L Stainless steel 316L 130~190 -100~+550
Outer ring is often made from carbon steel subject to anti-corrosive treatment.

Flange type and form of wrapping pad:
Flange type Spiral wound gasket form
Flat face flange(F.F) Wrapping pad with outer ring only
Wrapping pad with inner and outer rings
Raised face flange(R.F)  Wrapping pad with outer ring only
Wrapping pad with inner and outer rings
Male and female flange(M & F) Basic wrapping pad
Wrapping pad with inner ring only
Tongue and groove flange(T & F) Basic wrapping pad
Wrapping pad with inner ring only
Flat and groove flange(F & G) Basic wrapping pad
Wrapping pad with inner ring only

Wrapping pad thickness tolerance:
Item Thickness(mm) Tolerances(mm)
Gasket thickness 4.5, 3.2 +0.2
Ring thickness 3.0 0.24

Key technical parameter of metallic wrapping pad:
Wrapping pad coefficient m=2.5-4
Wrapping pad service pressure 25MPa
Wrapping pad service temperature -196-700(Oxidizing medium no higher than 600)
Wrapping pad minimum pretension specific pressure y=68MPa

The following table refers to tolerances for the diameter of wrapping pad (namely the nominal pipe diameters for the use of flange):
  DIM(mm) ANSI B16.5
Mss sp-44
API605 Tolerances
Inner ring diameter
Pad inner diameter
<=600 =24" 26" and =34" 0.5
600 and =800 24" and =34 36" and =60" 0.9
800 and =1600 34" and =60"   1.3
60"   1.6
Pad outer diameter =600 =24" =24"
600 and =160000 24" and =60"   1.8
1600 60"
Outer ring diameter     1/2" and =60" 0.9
=600 =24"   0-1.0
600 and =1000 24" and =34"   0-1.8
1000 and =1600 34" and =60"   0-2.2
Note: We also tailor products based on JIS, JPI or customer requirement

Ordering information: The following parameters should be specified during ordering for metallic wrapping pad
1. Type of metallic wrapping pad: A B C D
2. Flange standard: ASME B16.20
3. Pipe through diameter, pressure rating: 2"150Lbs
4. Material: inner ring SS316; metallic wrapping belt SS316; packing belt: graphite; outer ring; carbon steel

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