Anchor Load Calculations and Guide Spacing Requirements

If you do not guide, then your joints will not last. When guided incorrectly, the joints can overextend, leading to significant damage. This means the joint will need to be replaced. Avoid this by watching the video below by Metraflex. Jim Clauss goes into detail about how to properly calculate Anchor Load Calculations and Guide Spacing Requirements so that everything will go smoothly and last for its appropriate lifetime. 

Here are a few of our takeaways:

1. There are three major loads that make up your anchor load:
   
   Pressure Thrust
    - This is often the largest of the loads, but it is also the most often overlooked.
    - Find this by calculating the area of the “mean” diameter of the bellows.
   
   Deflection Load (Spring Load)
   - The force is take to bend the corrugated stainless steel bellows. 
   - Find this by finding the spring rate of your joint and multiplying it by its full movement.
   
   Friction Resistance
   - The force it takes to overcome the friction of any hangers and guides in the piping system.
   - Multiply the total weight of the pipe and the fluid inside by 0.3.
   
   
2. Metraflex put these to the test by calculating an achor load for 6” Sch. 40 carbon steel with a Metragator:
   1. For example, a 6” 150 lb. Metragator with 4” axial movement has an effective area of 58.9 IN² and a spring rate of 269 lbs./inch.
      • To find the pressure thrust we multiply 58.9 times the test pressure of 150 PSI to find 8,835 lbs.
      • To find the spring rate we multiply 269 x 4 (movement of the compensator) to find 1,076 lbs.
      • To find the frictional resistance we multiply the weight of carbon steel pipe of the weight full of water (31.49) lbs. per foot) by length 250 feet times .3 to find 2,361.75 lbs.
      • Add those three answers together and you get 12,272.75 lbs.
        
3. When determining guide space requirements, there is a universal guide from the Expansion Joint Manufacturers Association called the Concentric Pipe Guiding Spacing that should be used.
   • If it is a curved pipe, then the guide for the straight pipes does not apply, there are more loads.
   • If you need a quick answer, cut your guide spacing in half.
   • The guide also does not apply to risers.
     
     
   
   4. DO NOT test your system without having all the guides and anchors properly installed.
   • It does happen, so be sure everything is properly installed before testing.
     
     

If you have any questions about Metraflex products or applications for projects, you should contact your local manufacturer’s rep.