Tag: videos
High Temperature Pipe Supports (Hot Shoes) Product Video
Hold-Down Pipe Clamps Product Video
Function of PT&P’s Bulletproof Protection Shield (Critical Defense Product)
Function of a Constant Spring
PT&P’s Polyurethane Foam Machine
How to Inspect a Hydraulic Snubber
How to Remove Travel Stops from a Constant Spring Hanger
How to Install a D-Type Variable Spring Support
Solution for Removing Travel Stops in Variable Cans at Heavy Loads
For spring cans carrying a load of 40, 000lb or greater, we recommend you use jacking bolts to remove the travel stops.
- Set the load column to put as much pressure on the coil as you can.
- Loosen both jacking bolts.
- Remove travel stops with pliers.
Spring Loading Procedure for Standard Variable Springs
Function of a Variable Spring Hanger
DESCRIPTION OF A VARIABLE SUPPORT HANGER
Variable support hangers are used to support components and structures (e.g. pipes, vessels, etc.) that experience vertical movement. Unlike constant support hangers, the variable support hangers are used where the supporting components have the capability to withstand load variations of up to 25%.
The vertical movement is accommodated by a compression spring coil (or stack of coils in series) which is pre-compressed to an initial load setting. During operation, the supported component will travel through its specified movement and the coil(s) will be compressed/decompressed to the final load setting. This difference, or variation, in loads between the initial setting and the final setting gives rise to the term “variable” spring support.
A maximum variability factor of 25% has been established by MSS to limit the load differential which may be prescribed in a variable spring support. The variability is a ratio of the change in load compared to the final load. When prescribing variable spring supports, attention must be given to the spring rate and the desired amount of travel to insure the variability factor remains below 25%.
The movement of a variable spring hanger rod supporting a load is animated in the video clip. The initial load position is designated as “cold position” in the animation. As the load moves upward, the spring is decompressed to the final load position designated as “hot position”. The load difference (variation) is produced by the coil’s change in compression multiplied by the spring rate. The change in compression of the coil causes a direct change in the supported load as seen at the hanger rod.
How to Remove Travel Stops from a Variable Spring Hanger
Function of a Constant Spring Hanger
DESCRIPTION OF A CONSTANT SUPPORT HANGER
Constant support hangers are used to support structures and components (e.g. pipes, vessels, etc.) that experience vertical movement. The constant hangers provide support at critical locations of a structure such that the temperature dependent deformation of the structure does not produce any excess stress in the structural system.
Theoretically, a constant support provides a constant force on the structure so that it does not experience any extra resisting forces from the support. However, in reality, complete constant load reaction is not possible. That is why the MSS standard allows a maximum tolerance of 6% of the constant load throughout the entire travel range.
Constant resistance to a moving load is achieved by balancing the moment of the moving structure by the moment produced by the force of a compressing/decompressing spring about a common pivot point.
The movement of the constant hanger rod, supporting a load, is animated in the video clip. As the hanger rod connected to the cam moves down (or up) on the left hand side, the spring on the right hand side is compressed (or decompressed) by the spring rod.
Here, the moment of the external load acting downward along the hanger rod varies as the supporting pipe moves (down or up). The variations of the moment (due to changing moment arm length) of the moving external constant force is balanced by compressing (or decompressing) the spring with the lever arm about the same pivot point.
In designing a constant support hanger, minimum variation of the load is optimized via selecting the proper arm lengths of the external force and the spring force, and the spring constant for a given total displacement of the external load.
Variable Spring Supports Product Video
PTFE Slide Plate Inspection and Maintenance
Follow these steps when inspecting and maintaining PTFE slide plates.
1. Inspect welds between backing plate and bottom of the saddle
2. Inspect adhesion of the PTFE slide plate
3. Inspect welds of the base plate of the bottom slide plate between the structural steel
4. Make sure you have a clean surface between the upper and lower slide plates