Week 11 Challenge

Aim:-

To Model and Design a typical pipe rack bent in Oil Plant using STAAD Pro.

Given data:-

Height of Column = 9 m

Height of First tier = 6 m

Height of Second tier = 7.5 m

Height of Third tier = 9 m

Width of Pipe Rack = 7.5 m (C/C of Column in width of pipe rack)

Span of each Bay = 6 m

Number of bays = 7

Top tier of pipe rack has 3 number of cable trays each 150 mm wide

Second tier of pipe rack has 4 pipes, one of 24 " dia and one of 12 " dia, remaining two pipes are of dia 8"

First tier of pipe rack has 6 pipes, one of 18 " dia and remaining 5 pipes are of dia smaller than 8"

Procedure:-

Step 1:-

Following Loads are to be assigned:

1) Structural Dead Load:

Load due to weight of Structure excluding weight of pipe

2) Operating Dead Load:

Weight of pipe, fluid in it and insulation.

UDL of 1.9 kN/m² is assumed for pipe of dia 8".

Point load is considered at appropriate location for pipe larger than 8" dia pipes which will be reported by Piping Engineer.

3) Empty Dead Load:

Weight of empty pipe without fluid in it but including insulation, it is assumed as 60% of operating load.

4) Test Dead Load:

In case test medium in pipe is not known, water with density of 1000 Kg/m³ is considered as test medium so generally test load is same as operating dead load.

5) Cable Tray Load:

UDL of 1 kN/m is considered

Step 2:-

• Load Calculations for Dead load, Operating load and Empty Load.

Dead Load Calculation:

Lets assume Selfweight as 1.1 factor. Where 10% extra for connections.

Longitudinal members are assumed to ISMB 225.

Weight of ISMB 225 is 31.2 kg/m = 0.312 kN/m

Load due to Longitudinal member = 0.312 x 6 = 1.87 kN

Operating Load Calculation:

Weight of Pipe upto 8" = 1.9 kN/m²

Load acting on deck slab = 1.9 x 6 = 11.4 kN/m

Weight of Pipe 12" = 1.49 kN/m²

Load acting on deck slab = 1.49 x 6 = 8.94 kN/m

Weight of Pipe 18" = 2.66kN/m²

Load acting on deck slab = 2.66 x 6 = 15.96 kN/m

Weight of Pipe 24" = 4.06kN/m²

Load acting on deck slab = 4.06 x 6 = 24.36 kN/m

Empty Load Calculation:

Empty Load is taken as 60% of Operating load = 0.6 x 11.4 = 6.84 kN/m

Test Load Calculation:

Test Load is the load of pipe carrying water as Operating load = 11.4 kN/m

Cable Tray Load Calculation:

Cable Tray load = 1 x 6 = 6 kN/m

Step 3:-

• Open Staad Software, create a new file.
• In Geometry tab model a Pipe rack structure using Nodes, Beams command as shown below.

Step 4:-

• Select Properties Tab, click Section Database and Choose the sections required.
• Then assign the sections to the members.

Step 5:-

• Then Create a Fixed support and Fixed but support.
• Now assign the supports to the model.

Step 6:-

• Now add the Load cases and assign the load cases to the model as shoen below.

Step 7:-

• Now go to Analysis tab and select define commands.
• Then select Perform analysis and click ok.

• Output show 0 Errors and 0 Warnings.

Result:-

• Modelling and Designing of a typical pipe rack bent in oil plant was done successfully.