Technical Information – Spiral Wound Gaskets

Structure

A spiral-wound gasket is made of alternate plies of V-preformed hoop and soft filler that are tightly and spirally wound together. The metal winding around the entire inside and outside circumferences of the gasket is spot welded. Normal practice is to reinforce the inside and outside diameters with several plies of the metal winding without a filler being introduced. According to the need of the mating flange, the gasket is provided with an outer ring, an inner ring or both outer and inner rings.

The outer ring serves as a compression stop, anti-blowout device, which properly centers the gasket on the flange. The inner ring acts as a compression stop and is used to fill the annular space between the flange bore and the gasket inside diameter to minimize turbulence of process fluids and erosion of flange faces.

 

spiral_gasket_dia1

 

On rare occasions, applications for spiral-wound gaskets arise where it is necessary to utilize a spiral-wound outer and/or inner ring. The spiral-wound outer or inner rings are used primarily as reinforcement and are chosen instead of a solid metal ring, because of lower costs or because of limited space when the use of a solid metal ring would be prohibited due to the difficulty in fabrication or usage.

 

spiral_gasket_dia2

 

Features & Benefits

1. No skilled assembling works are necessary because the gasket can seal perfectly if it is compressed tospgasket
the recommended thickness (for instance a 4.5mm thick gasket may be compressed to the thickness ranging from 3.2 to 3.4mm). If the gasket has an attached outer ring, the ring serves as a guide for compression.

2. By changing the material of hoop or filler or by attaching ribs or rings, the gasket’s application range may be increased not only on pipe flanges but also on the joints of other industrial machinery including automobiles.

3. There is no worrying about leakage under cryogenic temperature services.

4. The gasket withstands high-temperature and high-pressure services. There is no decrease in its sealability found even if operating conditions should suddenly change. It would neither cause any leakage nor would it get damaged if exposed to heat or pressure cycle additional heat stress.

5. The total cost of the machinery and equipment can be reduced because no accurate finish of gasket seating face is necessitated, for example the roughness 25S as specified by JIS is acceptable.

6. The cost of gasket replacement can be reduced because the gasket hardly coheres to the mating face thus making it easy to clean.