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发表于 2024-5-29 13:45:28
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3.4 Example E3.3 - Determine the M D M T for a Nozzle-to-Shel l Welded Assembly
Determine if impact testing is required for the proposed nozzle assembly comprised of a shell and integrally
reinforced nozzle. The shell is cylindrical with all Category A joints made up of Type 1 butt welds which have
been 100% radiographically examined. The nozzle parameters used in the design procedure is shown in Figure
E3.3.1.
Vessel Data:
• Material = SA - 5 1 6, Grade 70, Normalized
• Design Conditions = 356 psi @ 300° F
• Inside Diameter = 1 50 in
• Nominal Thickness = 1 . 8 125 in
• PWHT = Yes
• MDMT = -20°F
• Weld Joint Efficiency = 1 .0
• Corrosion Allowance = 0. 1 25 in
• Allowable Stress at Ambient Temperature = 20000 psi
• Allowable Stress at Design Temperature = 20000 psi
Nozzle:
• Material = SA - 1 05
• Outside Diameter = 25.5 in
• Thickness = 4.75 in
• Allowable Stress at Ambient Temperature = 20000 psi
• Allowable Stress at Design Temperature = 20000 psi
The nozzle is inserted through the shell, i.e., set-in type nozzle.
In accordance with paragraph UCS-66(a)(1 )(-a)(-4 ), the procedure that is used to establish the governing
thickness, tg , is shown below.
Paragraph UCS-66(a)(1 )(-a)(-4): for welded assemblies comprised of more than two components (e.g., nozzle-to
shell joint with reinforcing pad), the governing thickness and permissible minimum design metal temperature of
each of the individual welded joints of the assembly shall be determined, and the warmest of the minimum design
metal temperatures shall be used as the permissible minimum design metal temperature of the welded assembly.
See Figure UCS-66.3 Sketch (g) and Figure E3.3.1 of this example.
a) STEP 1 - The appropriate impact test exemption curve for the cylindrical shell material specification
SA - 5 1 6, Grade 70, Normalized from the Notes of Figure UCS-66, was found to be Curve D. Similarly,
the appropriate impact test exemption curve for the integrally reinforced nozzle material specification
SA - 1 05 from the Notes of Figure UCS-66, was found to be Curve B.
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