what is the criteria for deciding that there is requirement of anchor block in an undergroung piping model.
In one of my system, a 24" line after coming out of equipment is going undergroung in same plane at a buried depth of 1m with bend radius 40D. now if I am using anchor block in this line, a huge load is coming on equipment nozzle. I can not change routing of underground piping and equipment location is also fixed. Plz suggest me any solution for this problem

Hello there,

Anchor block is required in most cases for U/G pipeline according to design practices. Clarify with your client.

You are right in saying that anchor blocks are often required, but on what basis? what is the design practice involved for providing an anchor block. Client only says that you have to use anchor block but the location of anchor block in a pipeline and its design has to be decided by a stress engineer.

As far as I know, you should isolate pipeline from surface facility. Let say, isolate B31.4 code from B31.3 code. Normally you put anchor block outside of fence to compensate large forces and moments.

Typically anchor / thrust blocks are required for buried piping where mechanical (ie: push on) joints are used. The blocks are located at all changes in directions, this is to stop the joints from opening up due to the internal pressure, think about what happens to a hose when you turn the tap on full bore.

If you have pipe of welded construction you probably don't need an anchor block at all. What you should do is model the piping system and run the buried model using known soil data from your civil group. Once you've done this you can then review the requirement for additional anchors in the buried section.

If you are not dealing with mechanical joints then think of your system as an aboveground system that has continuous restraints.

In a U/G pipeline, after specific length (Virtual Anchor Length) adjacent soil acts like an anchor and you don't need to model the rest of pipeline. If you should decide whether use anchor or not, after converting your model to soil model, add an anchor then run analysis. Run analysis again without anchor. Compare two results and make your decision.