The Quality Series QRW-20 and QTW-20 are designed so that they can be welded directly on to a pressure vessel. Weld pad gauges are used where regular gauges and valve construction in impractical, due to space constraints, solid matter in the suspension and thermal stresses on the gauge glass from the associated piping. Included are applications involving high vibration, highly viscous liquids or liquids with considerable amounts of solids.

Quality Weld Pad Gauges are available in both reflex and transparent applications. These gauges are designed to take pressure within the gauge itself. These gauges are not designed to replace the tank strength lost due to slotting the pressure vessel. It is therefore impossible to give a pressure rating to the weld pad gauge.

  • Flat glass liquid level gages designed to become an integral part of the vessel.
  • For direct mounting to vessel wall.

Standard Welding Pad Gages

Design and Installation:Standard Quality weld pad gauges follow other Quality flat glass gauges in general design and materials, except for the method of attaching to the tank or vessel.  The chamber of the welding pad gage consists of a bar stock pad, which is welded to the tank after cutting a slot in the tank wall equal in dimension to the vision slot of the gage. Alternately, for maximum vessel strength without further reinforcement, two holes may be drilled in the tank wall with diameters equal to the width of the vision slot of the gage located at the top and the bottom of the visible range.   For best results the tank wall behind a reflex gauge should provide a dark background. The holes, in lieu of of the slot method, can be used with a transparent type when there's sufficient visual contrast between the tank wall in the liquid to permit liquid level interface observation.

Pressure loads:

Where it is necessary to slot the tank because of the nature of the liquid or there is need to observe the color or interface of the liquid, the following facts must be considered:

Standard and welding pad gages will withstand a loading due to the pressure within the gage itself, but they are not designed to replace the tank strength lost with tank wall is cut. The gage manufacturer has no control over the loading in which the pressure vessel will impose on the pad. It is therefore impossible to rate welding pad gages. The tank fabricator must provide suitable tank wall reinforcement to prevent the pad from being distorted during welding or while under hot operating condition.

Materials and construction:

Quality weld pad gauges are engineered and built to Quality’s highest standards, using materials found by test to be the best for the particular application. The welding pad than in may be made of any material desired to withstand corrosive or other conditions.

To prevent distortion and during welding, welding pad gages may be furnished with a cold rolled steel space or to replace glass and gaskets.

Isolable Welding Pad Gages

Quality Isolable Welding Pad gages with control valves follow the general design of standard Quality welding pad gages but offer the additional advantages of integral valves.

Because the gauge can be isolated from the vessel by the valves, gaskets or glass can be replaced without lowering the level of liquid below the gage inlet or relieving pressure from the vessel.

Isolable gages are installed by matching valve inlets with holes drilled in the vessel in making a 100 percent for fillet Weld between the vessel wall and valve inlets. The gauge chamber is tack welded to the vessel.


Series QRW & QTW Gauge and Support Files

Series QRW & QTW Model


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