1. Location and Function

• Channel end covers (main sealing faces): Seal the two spiral channels (A/B sides).

• Manholes/handholes/flange nozzles: Auxiliary sealing points.

• Drain/vent nozzles: Small-diameter static seals.

Purpose: Maintain reliable sealing under differential pressure and thermal cycling, while allowing repeated assembly/disassembly.

2. Recommended Gasket Types

Preferred flange facings: Raised Face (RF), Male/Female (M/F), Tongue & Groove (T/G).
M/F or T/G offers better anti-blowout performance.

3. Materials and Pressure/Temperature Guidelines

• Metal winding/cores: SS304/316L common; avoid 304 in chloride/sulfur; 321/347 for high temp; Alloy 825/625 for severe media.

• Filler: Flexible graphite (general); PTFE/ePTFE for strong oxidizers/alkalis.

• Rings: Outer rings for centering and preventing over-compression; inner rings to prevent extrusion.

• Standards: ASME B16.20 (SWG/Kammprofile/RTJ gaskets), ASME B16.5/B16.47 (flange facings), tightening per ASME PCC-1.

4. Geometry and Compression (Typical)

• Compression range (SWG): 10–20%

• Recovery: ≥10%

• Seating stress (installation):

  • SWG with graphite: 30–60 MPa

  • Kammprofile: 20–40 MPa (check supplier data)

• Gasket width: ≥12–20 mm (depending on flange size)

• ID clearance: +2–3 mm over nozzle bore, to prevent edge erosion.

5. Bolt/Torque Calculation (General Steps)

1. Define required gasket stress σg and effective area Ag.

2. Seating load: Fg = σg × Ag.

3. Add pressure/operating load (using m, y factors if ASME method).

4. Bolt load per bolt: Fb = (Fg + Fwork) / N.

5. Torque: T ≈ K × Fb × db

   • K ≈ 0.16–0.22 (depends on lubrication)

   • db = bolt nominal diameter (m)

6. Tightening: 30% → 60% → 100%, in star pattern; re-tighten after thermal cycle.

6. Selection Guide by Service

• Coke oven gas (tar/naphthalene): SWG (graphite, SS316L windings) + inner ring, T/G or M/F face.

• Seawater/chloride cooling: SS316L/Ti + graphite or PTFE filler, bolts in 316/Duplex with anti-galling treatment.

• Vacuum service: Kammprofile preferred, maintains tightness at low pressure.

• Strong alkali/oxidizers: PTFE/ePTFE, with flange rigidity control.

7. QA/QC Requirements

• Docs: Material certificates (metal/filler), dimensional check records, T/P rating statements.

• Visual: No cracks, uniform winding, warpage <1 mm/300 mm.

• Dimensions: ID/OD/width/thickness per drawings.

• Marking: Grade, type, rating, batch number.

• Matching: Verify gasket type fits flange face (RF/MF/TG).

• Storage: Dry, flat, clean; graphite avoid oil; PTFE prevent creep deformation.

8. Installation and Maintenance

• Clean flange faces; remove oil/rust; flatness deviation ≤0.2 mm.

• Use same-batch gaskets; lubricate bolts/nuts.

• Tighten in multiple passes, cross/star sequence; record torque.

• Retorque after 24 h cold; recheck after hot run.

• Spare gaskets should be clearly labeled and stored properly.

9. Common Failures and Remedies

10. Example Procurement Data Sheet (Fields)

• Equipment tag/no.; design pressure/temp; flange facing (RF/MF/TG)

• Gasket type (SWG/Kammprofile/PTFE)

• Thickness and winding metal/filler materials

• ID/OD/width; with/without rings

• Standards (ASME B16.20, etc.); QA documents required

• Packaging and marking; quantities and spares