Alloy 600 ASTM/UNSP N06600 Barred Tee OD 10 " WT 3mm
 

 
 
 hollow tube or shel

Barred Tee

A barred tee is a tee or any fitting with a branch used in pipelines that is pigged and has a restriction bar welded internally preventing the pig from traveling down a branch connection.

Barred tee is a pipe fitting that is used in a pig launcher or receiver system in a piping system to ensure the pig could pass the branch ely
 

Design considerations for barred tee

• The barred tee will be used when there is a requirement for pigging. Thus, many of its applications can be found in the pipeline or in the subsea field.
• The bar plates that welded internally at the branch are to avoid the pig from changing direction or getting stuck at the branch outlet.
• The design of the bar plates must be in sufficient quantity, thickness and adequately spaced to ensure the smoothness for the pig to run through the main pipe, and at the same time not affecting the flow that was meant to flow through the branch. Normal practice is to ensure that the opening in the branch pipeline after guided bars is not more than 40% of the main pipeline area.
• The size of the bars in the branch connection has to be small enough not to restrict the flow but large enough to sustain the pressure of the flow.
• To ensure the smoothness, the bar plates have to be a grind to suit the branch curvature. Any sharp edges, spatters and burs are required to be removed. This smoothness of the pigging process is important to protect the sensor of the pig from damage.
• Refer to Shell DEP 31.40.10.13-Gen Figure 4 above; the quantity of the bar plates start with two (2) pieces and increase as the ID of the branch increase.
• The bar plates ideally will be equally spaced.
• For larger tee (size 14 inches and above), there will be a bridge plate in the middle to support the bar stiffness when getting hit by the pig.
• The material of the bar plates commonly used the same as the tee material for weldability.
• Standard practice is to avoid welding of guide bars directly on the high-stress concentrated areas of the extrusion neck. Bar ends must be machined to fit the branch.
• Weld Repairs on Parent metal is prohibited

 
   
 
    Corrosion resistance
Alloy 600 has corrosion resistance to various corrosive media. The composition of chromium makes the alloy have better corrosion resistance than nickel 99.2 (alloy 200) and nickel 99.2 (alloy 201, low carbon) under oxidation conditions. At the same time, the high nickel content makes the alloy have good corrosion resistance under reducing conditions and alkaline solution, and can effectively prevent chloride iron stress corrosion cracking. Alloy 600 has good corrosion resistance in organic acids such as acetic acid, acetic acid, formic acid and stearic acid, and medium corrosion resistance in inorganic acids. High purity water used in primary and secondary recycling in nuclear reactors has excellent corrosion resistance. The outstanding performance of 600 is that it can resist the corrosion of dry chlorine and hydrogen chloride, and the application temperature is 650 ℃. At high temperature, the alloys as annealed and solution treated have good anti-oxidation spalling properties and high strength in air.

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