BUTT WELD PIPE TEE AND CROSS
Steel tees are used to branch a pipeline at 90 degrees, crosses to make a double branch at 90 degrees each. In this article, we define pipe tees (equal and reducing) and crosses, which are butt weld fittings manufactured to ASME B16.9 (carbon and alloy steel) and MSS SP 43 (stainless steel and nickel-alloys), and provide details as types, dimensions, material grades.
BUTT WELD TEES
There are two main types of tees for pipes, equal and reducing:
EQUAL TEE (STRAIGHT TEE)
Equal tees, otherwise called straight tees, are butt weld fittings used to branch pipelines, or any other pipework, at 90 degrees.
These tees are defined “equal” as they feature the exact same outside diameter on for the run and branch sides (they connect pipes of the same diameter). To order an equal tee, it is sufficient to provide the nominal diameter, the schedule and the material grade of the fitting (sizes should match, of course, the dimension of the connecting pipes).
Equal tees are available in sizes from half an inch to 48 inches and above and are available both in seamless and welded execution (seamless up to 24 inches, welded for higher sizes).
Butt weld tees are manufactured according to ASTM B16.9 (carbon and alloy) and MSS SP 43 (stainless steel and nickel alloy). For more information about the materials for steel tees, you can read this article.
Reducing tees feature a smaller bore size for the branched pipe (generally of 2/3 sizes lower) compared to the bore size of the run pipe. If the required bore size reduction is bigger than 2 or 3 sizes, a reinforced branch connection (example a Weldolet) is recommended instead of a connection made with a reducing tee.
The standard dimensions and tolerances of straight and reducing tees are defined by the ASME B16.19 specification (carbon and alloy steel) and by the MSS SP 43 spec (for stainless steel and nickel alloys tees).
Barred tees are special types of straight tees used for pigged pipelines. They feature a welded restriction on the branch pipe side that prevents the pig from flowing from the run pipe into the branched pipe. The barred restriction that restricts the passage of the pig is welded on the internal side of the fitting (and looks like a cage). Barred tees are available only for the straight type (as a pig could not pass to the branched pipe if the bore size of the branched pipe is smaller).
PIPE TEE MANUFACTURING PROCESS
PIPE TEE DIMENSIONS AND MATERIALS
The dimensions and weights of butt weld steel tees are shown in this article.
The typical material grades for (butt weld) equal and reducing tees are explained in this article.
HOW TO ORDER PIPE TEES
To order a tee, the following parameters have to be provided to the manufacturer:
- Type of tee (equal tee/reducing tee)
- Run and branched pipe nominal size (d1 x d2 x d3, where d1 x d2 = inlets of the run pipe, d3 = tee outlet to the branched pipe)
- Schedule (wall thickness)
- Material grade (ASTM A234, A403, etc)
- Number of units
BUTT WELD CROSSES
Butt weld crossed are used when a double branch at 90 degrees is needed, i.e. in very rare cases. Crosses are seldom available from stock and, have, therefore, to be manufactured to order. Their dimensions are set by ASME B16.9/MSS SP43.
There are no specific limitations in terms of available sizes and schedules for butt weld crosses.