Spring loading systems for valves  

Due to their material structure, stuffing box packings show signs of settling. This is due to small air inclusions in the starting material, outgassing of impurities and the fact that the successive rings from the gland to the packing ring in contact with the medium are not compressed uniformly. These settling phenomena can be largely compensated by additional springing. 

Requirements for a re-equipment

• Equipment according to required specification (TA-Luft, FDA, BAM, ...)
• Service life according to specification and number of shaft movements
• Spring columns designed for packing type

Solutions

• Calculation of optimum / permissible preload forces
• Calculation of the required installation forces at operation
• Adjustment of the sealing pressure for operating under consideration of the installation technology
• Use of additional spring loading systems in case of settling phenomena

Design limits

• Design pressure: up to > 1100 bar
• Design temperature: up to approx. 750°C
• Packing diameter: without limitation
• Packing width: up to approx.30 mm
• Bolt size: up to approx. M36

Rotating Live Loading  

With permanently rotating shafts, the problem is not so much leakage as the risk of destruction of the packing by friction if the sealing force is set too high. Due to the constant shaft movement, more severe settling phenomena occur than with static equipment. 

Requirements for a re-equipment

• Equipment according to required specification (FDA, BAM, ...)
• Service life according to specification
• Spring columns designed for packing type

Solution

• Calculation of optimum / permissible preload forces
• Adjustment of operating sealing pressure
• Consideration of installation technology
• Use of adapted spring columns in case of settling phenomena

Design limits

• Design pressure: up to approx. 10 bar (Increase on request)
• Design temperature: up to approx. 200°C (Increase on request)
• Packing diameter: without restriction
• Packing width: up to approx.40 mm
• Bolt size: up to approx. M36

The concept of the spring columns  

The spring columns used are the conclusion of a development into which many experiences with the conversion of valves or shaft sealings in general have been incorporated. The most important features are:

• Installation of the spring loaded system without replacing the bolts
• Springs in a housing and thus protected against dirt and mechanical damage
• All body materials made of stainless steel 1.43xx (Grade 304 or Grade 316)
• Body materials optionally available in 1.4571 (Grade 316Ti
• Retrofit kits for metric threads M8 to M36 (in store up to M24)
• Retrofit kits for UNC threads from 5/16" to 1" (in store up to 3/4")
• Standardized sizes for spring column forces in different deflection force levels

The photo shows 2 possible variants of the spindle suspension. 

The PE variant (left side) is primarily used for valves. The springs are enclosed and the spring force is adjusted by bracing the cup and cover together until the maintenance gap at the bottom = "0". If the maintenance gap opens, the spring column can be re-adjusted to its operating force by retightening the nut. 

The PL version (right side) is primarily used for spring-loading slow-running shafts (sterilizers, conveyors). The adjustment of the operating force is less precise here and takes place when the shaft is started up. On the other hand, it is possible to generate significantly longer spring deflections in order to achieve a slower unloading of the spring columns. 

Data sheets of all standardized spring columns are available on request.