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ASTM A815 UNS S31803 BARRED TEE
A barred tee is a tee or other branch fitting used in pigged pipelines that has a bar welded internally to prevent the pig from travelling down a branch connection.
Barred Tee Design Considerations
The barred tee is used where there is a requirement for pigging. Therefore, many of its applications can be found in the pipeline or subsea environment.
The bar plates welded internally to the branch are designed to prevent the pig from changing direction or getting stuck at the branch outlet.
The design of the bar plates must be of sufficient quantity, thickness and spacing to allow the pig to pass smoothly through the main pipe, whilst not obstructing the flow through the branch. It is normal practice to ensure that the opening in the branch pipe after the guided bars is not more than 40% of the area of the main pipe.
The size of the bars in the branch must be small enough not to restrict the flow, but large enough to maintain the pressure of the flow.
To ensure smoothness, the bar plates must be ground to match the curve of the branch. All sharp edges, splashes and burrs must be removed. This smoothness is important to protect the pig’s sensor from damage.
Refer to Shell DEP 31.40.10.13-Gen Figure 4 above; the number of bar plates starts with two (2) and increases as the ID of the branch increases.
The bar plates will ideally be evenly spaced. For larger T-pieces (size 14 inches and above), there will be a bridge plate in the centre to support the stiffness of the bar when hit by the pig. The bar plate material is usually the same as the tee material for weldability. It is standard practice to avoid welding guide bars directly onto the high stress concentrated areas of the extrusion neck. Bar ends must be machined to fit the branch. Weld repairs to parent metal are prohibited.
ASTM A815 UNS S31803 BARRED TEE
What is ASTM A815?
It is standard specification for Wrought Ferritic, Ferritic/Austenitic, and Martensitic Stainless Steel Piping Fitting.
This specification covers two general classes, WP and CR. Class WP fittings are subdivided into four classes:
- WP-S, seamless products.
- WP-W, welded products.
- WP-WX, Pipe fittings which contain welds where all welds have been radiographed.
- WP-WU, fittings that contain welds where all welds have been ultrasonically tested.
UNS S31803 Tee Chemical Composition %
| C | Mn | P | S | Si | Ni | Cr | Mo | N |
| 0.03 | 2.00 | 0.03 | 0.02 | 1.00 | 4.5-6.5 | 21-23 | 2.5-3.5 | 0.08-0.20 |
UNS S31803 Tee Mechanical Properties
| Yield Strength MPa | Tensile Strength MPa | Elongation min % | HBmax |
| 66/450 | 90/620 | 20.0 | 290 |
The Difference Between A Tee And A Barred Tee
| Parameter | Tee | Barred Tee |
| Definition | Standard Pipe Fitting | A special type of piping component |
| Manufacturing | Generally by Extrusion or forging | Mostly Fabricated |
| Use | Used in both piping and pipeline engineering | used in pipeline engineering near the pig launcher/receiver |
| Design Code / Standard | ASME B 16.9/MSS SP 75 | Shell DEP 31.40.10.13-Gen or ISO 15590-2 |
| Production Quantity | Large scale in bulk | Select small quantities (custom made) |
| Cost | Cheaper | Costlier than normal Tee |
ASTM A815 UNS S31803 BARRED TEE
C&N guarantees high quality ASTM A815 Uns S31803 Duplex Steel Butt welded Tee, S31803 Duplex Pipe Fitting. At the same time, we are committed to providing our customers with dedicated and perfect service.
