Difference between Tee and a Barred Tee

Butt Weld Fitting Materials Butt Weld Tees Design and Engineering Equal Tees

Standard Tee or a Barred Tee are fittings used in piping and pipeline engineering design. Piping standard tees are coming in equal tee and reducing tee, however in piggable pipelines a Bar or Barred Tees are used at the Tee branch connections. This is also called sometimes as Pigged Tee.

Barred Tee or Bar Tee
Barred Tee or Bar Tee

Why is Barred Tee used in piggable pipelines?

Barred Tee name itself is indicating purpose. Meaning of barred is to prevent or stop from something being happened.

Piggable pipelines pig is being introduced inside the pipeline during pigging. However, to prevent the travelling of pig from main pipeline header to its branch pipes, barred tees are used.

A Barred Tee or Bar Tee Design

A Barred Tees are fabricated using Standard Tees, with bar plates welded at branch outlet of standard Tee. These bar plates will stop or prevent pig to travel inside branch header.

Some of the process considerations, shall be taken care while designing barred tees. Like flow or pressure drop considerations. Hence to maintain pressure drop requirements, bars size shall be small.

Pig Sensors are very sensitive to abrasive or burrs inside pipelines, and this may cause damage to pigs. Hence design of barred to bar plates, shall be smooth and should have precise edges.

Material selection for barred tee mostly considered, as same of parent pipe.

To avoid damage to barred tee bar plate, a connected plate will be installed at the middle of larger 14” and higher size tees, which will support the bar stiffness.

There are no separate international standards for bar tee design. Barred tees are designed from Standard Tees design standards, and also followed ASME B16.9 or MSS-SP 75.

Barred Tee Design

Standard practice is to avoid welding guide bars directly on the high-stress concentrated areas of the extrusion neck. Bar ends must be machined to fit the branch.

Summary:

Comparison summary of Standard Tee and Barred Tee or Bar Tee is as below,

  • Tee is a standard fitting, however a Barred Tee or Bar Tee is a special type of fittings.
  • Manufacturing method used for Tee is extrusion or forging, however a Bar Tee is mostly fabricated.
  • Application of standard Tee is in piping and pipeline; however, a Bar Tee is used in pipeline for piggable lines.
  • Standard fitting is designed based on ASME B16.9/MSS SP 75, however a Bar Tee or Barred Tee will be designed based on shell DEP’s or ISO 15590-2.
  • Cost wise standard Tee is cheaper than a Bar or Barred Tee.