## Sunday, October 14, 2012

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### Pressure Design Straight Pipe (Run Pipe)

• STRAIGHT PIPE THICKNESS UNDER INTERNAL PRESSURE (tm) , mm.
Formula used are:

tm =[(PDo)/2(SE+PY)]+A  and   tm =(Pd+2SEA+2YPA)/2(SE+PY-P)

where:

 P Internal Design Gauge Pressure, N/mm2. Doh Outside Diameter of Pipe, mm. S Stress Value for Material, N/mm2. E Quality Factor For Longitudinal Weld Joints in Pipes. Y Coefficient for Materials. d Inside Diameter of Pipe, mm. A sum of mechanical, corrosion, erosion allowance,mm.

### Reinforcement of welded branch connections

Formula used are:
• d1 = [Dob - 2(Tb - A)]/sin α
• d2=  greater of d1 or (Tb - A) + (Th - A) + d1/2
• L4 = lesser of  2.5(Th - A), mm or 2.5(Tb - A) + tr, mm.
where:

h subscript referring to run or header.
b subscript referring to branch.

 Th
nominal thickness of run or header.

 Tb
nominal thickness of branch.
d1 effective length removed from pipe at branch, mm.
d2 "half width" of reinforcement zone, mm.
L4 height of reinforcement zone outside of run pipe, mm.
Tb branch pipe thickness, mm.
Th run pipe thickness, mm.
tr minimum thickness of reinforcing pad, mm.
tmh pressure design thickness of run pipe, mm.
tmb pressure design thickness of branch pipe, mm.
α smaller angle between axis of branch and run.
Dob outside diameter of branch pipe, mm.
Doh outside diameter of run pipe, mm.
• A7 = (tmh - A)d1(2 - sinα), mm2
• A1 + A2 + A3 + A4 + A5 >= A7
where:

 A1 Area resulting from excess thickness in the run pipe wall, mm2. A2 Area resulting from excess thickness in the branch pipe wall, mm2. A3 Area provided by deposited weld metal beyond the outside diameter of the run & branch, mm2. A4 Area provided by a reinforcing ring, pad or integral reinforcement, mm2. A5 Area provided by a saddle on right angle connection, mm2. Dr Outside diameter of reinforcement ring, mm. Sr Stress value for reinforcement ring material, N/mm2. ha Height of the fillet weld between run pipe & reinforcement ring, mm. hb Height of the fillet weld between branch pipe & reinforcement ring, mm.

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