An SS (Stainless Steel) inner ring, commonly found in spiral wound gaskets, is a metal ring used to prevent buckling of the spiral winding and to protect the gasket from erosion and debris buildup. It acts as an additional compression stop, minimizing the chance of gasket material being drawn into the pipe and causing issues like "bird's nests". The inner ring also helps reduce turbulent flow, which can lead to flange erosion. 

Here's a more detailed explanation:

• Function:

  The inner ring is primarily a structural element that prevents the spiral wound gasket's windings from buckling inward, especially under high pressure or temperature. 

• Prevention of "Bird's Nests":

  When a gasket buckles, pieces can be sucked into the pipe and travel through the system, potentially wrapping around pumps or other equipment. The inner ring helps prevent this by acting as a physical barrier. 

• Turbulence Reduction and Erosion Protection:

  By filling the annular space between the pipe bore and the gasket's inner diameter, the inner ring minimizes turbulent flow and protects the flange bore from erosion. 

• Compression Stop:

  The inner ring also acts as an additional compression stop, preventing excessive compression of the gasket during installation or operation. 

• Material:

  Inner rings are typically made of the same stainless steel material as the gasket's windings, such as 316SS, to ensure compatibility and strength.