All Welded System (AWS) Diaphragm Seals: The Problem Solver

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Committed to constant improvement, WIKA Instrument, LP collaborated with diaphragm seal users in the process industry to identify problems they had with traditional diaphragm seals. WIKA’s findings resulted in the design of the All Welded System, whichsolves problems associated with traditional seals.

The problems and the solutions

Problem: Clamping bolts loosened in vibration and thermal cycling applications.

Solution: WIKA’s body construction welds together the upper and lower halves of the diaphragm body.  The clean welding design supports vibration and thermal cycling applications, and eliminating the traditional hardware of bolted seals also reduces the space requirements for the assembly.

Problem: O-Ring and/or gaskets were not always compatible with the process being used.  

Solution: The diaphragm is recessed and welded to the lower body of the AWS using a TIG weld technique. Eliminating O-Ring and gaskets eliminates process compatibility issues and enhances the instrument’s upper temperature limits while also maintaining material compatibility between the lower body and the diaphragm.

Problem: The thread contact between the gauge and seal changed in extreme temperature and vibration applications and during instrument installation and orientation.

Solution: The seal upper housing, designed to mate with the threads of the process gauge, is welded, enabling the thread contact to be fully resistant to thermal cycling, vibration, and incorrect installation. The back weld ensures that integrity is always maintained between the instrument and the seal. Plus, it eliminates the potential loss of system fill fluid through the threads, a particularly critical issue with this NPT connection. Because the gauge cannot be unthreaded from the diaphragm seal, the assembly qualifies as a dual-containment system.

More features of the AWS

  • The WIKA Model 23X.34 process gauge easily converts to liquid fill, making it resistant to resonant frequencies and vibration damage.Its pressure gauge housing is a safety case with blowout back.
  • The movement has a built-in 30% over-range protection with no loss of accuracy.
  • The 23X.34 design also includes a mechanical over and under stop safety mechanism.
  • This AWS design will safely work up to 300° F using a thermoplastic case.
  • The standard available bourdon tube and socket materials are Monel® and 316SS.

Additionally, WIKA’s AWS assembly is fully traceable. Order and material information is engraved on the gauge,

Contact WIKA for more information about the right AWS diaphragm seals and instrumentation for your plant’s requirements.

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