Tag: Gaskets

1. Identify Application Requirements

• • Service Conditions: Determine the operating temperature, pressure, and medium (e.g., gas, liquid, corrosive chemicals) the gasket will be exposed to.

• • Flange Type: Identify the flange design (e.g., raised face, flat face, ring-type joint) per standards like ASME B16.5 or B16.47.

• • Piping or Vessel Code: Confirm the applicable ASME code (e.g., ASME B31.3 for process piping or ASME Section VIII for pressure vessels).

2. Select Gasket Material

• • Compatibility: Choose a material compatible with the process fluid to avoid degradation (e.g., rubber, PTFE, graphite, or metallic materials like stainless steel).

• • Temperature and Pressure Limits: Ensure the material can withstand the maximum temperature and pressure of the system. ASME standards provide guidance on material performance under these conditions.

• • Corrosion Resistance: Consider the environment and potential galvanic corrosion between the gasket and flange materials.

3. Determine Gasket Type

• • Non-Metallic Gaskets (ASME B16.21): Soft gaskets (e.g., rubber, PTFE, compressed fiber) for low-pressure, non-critical applications.

• • Metallic Gaskets (ASME B16.20): Spiral-wound, ring-type joint (RTJ), or solid metal gaskets for high-pressure, high-temperature, or critical services.

• • Semi-Metallic Gaskets: Combination of metal and filler (e.g., spiral-wound with graphite) for versatility in moderate to severe conditions.

4. Size and Dimensions

• • Match the gasket dimensions to the flange size, adhering to ASME B16.20 (metallic gaskets) or B16.21 (non-metallic gaskets). This includes inner diameter (ID), outer diameter (OD), and thickness.

• • Ensure proper fit to avoid overhang or insufficient coverage of the sealing surface.

5. Evaluate Gasket Performance Factors

• • Seating Stress: Calculate the minimum and maximum seating stress required to achieve a seal, using ASME Section VIII, Division 1, Appendix 2. This involves gasket factors “m” (maintenance factor) and “y” (yield factor).
    • • m: Ensures the gasket maintains a seal under operating pressure.
    • • y: Ensures sufficient initial compression during bolt tightening.

• • Bolt Load: Confirm the bolt load is adequate to compress the gasket without exceeding flange or gasket limits.

6. Consider Design and Installation

• Flange Surface Finish: Verify the flange surface roughness aligns with gasket type (e.g., smoother finish for soft gaskets, specific serrations for spiral-wound).