Weldolet or Pipe To Pipe

Questions like yours (relating to pipe Branches) have come up before, in fact many, many times before.

Below is my answer to a previous related question:

Branch Selection Tables

The question:

How can one know whether stub-in/stub-on or fitting connection is required or not for branch connection? In fitting type whether one should go with Tee or o'let?

My answer:

First:

When you ask this question are you a Designer doing piping layout?

Or, are you a Piping Material Engineer (PME) developing the piping line class specifications?

It makes a difference who (functionally) is asking the question.

Functionally if you are the piping designer doing piping layout then you use the information supplied on the "Branch Selection Tables" provided by the PME in the Line Class specs. See Attachment "B" for a Sample Branch Selection Table.

Functionally if you are the PME developing the "Branch Selection Table" for the Line Class Specs than it is a different role and my answer is different and longer.

As the PME developing the "Branch Selection Table" you need to know:

· The commodity

· The pressure (Design & Operating)

· The temperature (Design & Operating)

· Corrosion allowance

· Along with all the other data used to select the line class base material

Then you make "If – Then" judgment calls based on good engineering practice and economics.

For example, assume a Header size of 8", 10" or 12" (200mm, 250mm or 300mm):

· If – the commodity is Cooling Water at low temperature and low pressure and the branch is size to size – Then you should use a TEE

· If – the commodity is Cooling Water at low temperature and low pressure and the branch is size to one size smaller – Then you should use a Reducing TEE

· If – the commodity is Cooling Water at low temperature and low pressure and the branch is size to two or more sizes smaller – Then you should use a Stub-In (or Stub-On)

· If – the commodity is Hydrocarbon at very high temperature and high pressure and the branch is size to size – Then you should use a TEE

· If – the commodity is Hydrocarbon at very high temperature and high pressure and the branch is size to one size smaller – Then you should use a Reducing TEE

· If – the commodity is Hydrocarbon at very high temperature and high pressure and the branch is size to two or more sizes smaller – Then you should use a Weld-O-Let

Each and every branch situation expected on the job should be considered and the proper calculations run (based on the applicable project design Code example: ASME B 31.1, B 31.3, etc.) to verify and document the basis of the selection.