Spring Can Pipe Support

[harith07]

Hi,
What does cold setting and hot setting on Spring Can pipe support means? If I have a cold and hot setting on a Spring Can pipe support on an isometric showing the same setting reading, does that mean there will be no movement on the pipe even during operation(hot).
Thanks.

 

[C2it]

Recalling the obvious, spring supports are designed to support pipe which will move up or down with (usually) thermal expansion in the pipe.

The hot setting is the load the spring is designed to carry when at operating height (the real deadweight load). The cold setting is the load it would be installed at. The difference is the colt to hot travel multiplied by the spring rate. So if the operating movement cold to hot is up, then the cold load will be larger than the hot load.

If the two values are the same it would suggest that the spring is a constant force type. These use a coil spring in compression, but with cunning lever arms which cancel out the spring rate effect. Check out for instance,

http://www.cp-ltd.co.uk

for common designs, or google Lisega for a different approach to constant springs.

 

[ApC2Kp]

harith07,

If there is no deflection (or very small deflection) of piping, the spring can pipe support might be located at a neutral point in the piping system, that is, a specific position in which the piping rotates or bends around the point. A fixed support could be used there in place of a spring.

If the stresses and loads are OK, then leave the support at that location - many times the available structural steel dictates the location of supports. If the spring can is small (low cost), then it could be left in the design. A large spring can could be replaced with a rigid support to save cost and eliminate a future maintenance item.

If there is significant deflection at the support point of the piping, then like c2it has stated, the spring can could be a constant force type. These are usually required for a deflection greater than 2 inch (50 mm), and have a variance of less than 5% over their travel range. These are costly, and if installed in a corrosive plant environment, will not last long before the mechanism binds up from rust and dirt. The constant type spring supports would serve better in a clean power plant turbine building.