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Thread Seals

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Fastener and Fitting Seals


Thread seals have been designed to seal the threads of machine screws, studs, and similar items. They are made in one piece, the rubber sealing element being molded into the metal retainer. They utilize the principle of controlled confinement of the elastomer, permitting metal-to-metal contact of faying surfaces.

Most fluid systems have fasteners that must be sealed. Parker’s fastener seal designs found in the Stat-O-Seals® and Thread Seals® feature an elastomeric sealing element molded in place within a metal retainer (washer). Although resembling a simple o-ring groove concept, the mold in place fastener seal offers numerous advantages. Ideal for sealing small and miniature sizes, the Parker Lock-OSeal ® is a two-piece combination seal comprising a separately molded o-ring fitted within a surrounding metal washer. Other speciality fastener seals are also available.


  • Intended to seal the shank of a bolt immediately under the head
  • 600 Series: Intended for sealing standard series fasteners
  • NAS1523 Series: Applications that require conformance to NAS1523
  • 610 Series: Intended for sealing metric fasteners from 5mm to 22mm

Thread Seals

  • Intended for sealing directly on the fastener threads
  • 750 Series: Intended for sealing most UNC and UNF threads


  • 800 Series: Intended to seal the shank of a bolt immediately under the head
  • Ideal for sealing small and miniature sizes
  • Special material combinations not available as a 600 Series Stat-O-Seal

Specialty Products

  • Fastener seal kits
  • 250 Lock-O-Seals for sealing straight tube fittings and banjo style fittings
  • Food, beverage and FDA related applications
  • Custom designed fastener and fitting seals


  • How the Stat-O-Seal Works
  • Stat-O-Seal Features
  • 600 Series Stat-O-Seal
  • NAS 1523 Series Stat-O-Seal
  • 610 Series Stat-O-Seal
  • High Pressure Considerations
  • Stat-O-Seal Recommended Fastening Torque

Thred Seals®

  • Applications
  • ThredSeal Features
  • Key Benefits
  • Design Requirements
  • Maximum Pressure Recommendation
  • Installation Notes
  • Special Considerations for Adjusting Screws
  • 750 Series ThredSeal


  • 800 Series Lock-O-Seal

Part Number Conversion List

Specialty Products

Fastener and Fitting Seals