Pipe rack design - foundation loads

[Michel_Str]

Hi guys!
I am now involved in designing of industrial facility with a lot of piperacks. Eurocode standards.

Recently I got an 'interna client' standard saying that only 5% of live loads from piping (thermal, anchor etc) shall be taken to design foundations. With no word of explanatin about the background.

Are you familiar with this approach?
Hope to learn sth new

 

[HTURKAK]

Recently I got an 'interna client' standard saying that only 5% of live loads from piping

I could not figure out the 5% rule . Live loads from piping include the content weight .
By definition copy and paste from Process Industry Practice PIP STC01015 Structural Design Criteria

'Live loads are gravity loads produced by the use and occupancy of the building or structure. These include the weight of all movable
loads, such as personnel, tools, miscellaneous equipment, movable partitions, wheel loads, parts of dismantled equipment, stored
material, etc.'
I want to understand 5% rule is for ( horizontal ) friction load accumulation transferred to foundation . Copy and paste of the relevant clause;

'For pipe racks supporting multiple pipes, 10% of the total piping weight shall be used as an estimated horizontal friction load applied
only to local supporting beams. However, an estimated friction load equal to 5% of the total piping weight shall be accumulated and
carried into pipe rack struts, columns, braced anchor frames, and foundations.'

I will suggest you to look
- Process Industry Practice PIP STC01015 Structural Design Criteria,
- Design of Structural Steel Pipe Racks (RICHARD M. DRAKE and ROBERT J. WALTER ) You can get free copy . I have downloaded from AISC web site and attached for you.

 

[JoshPlumSE]

I could not figure out the 5% rule . Live loads from piping include the content weight .

I have a guess based on my time with heavy industrial projects and pipe racks. But, it is really just a guess:
a) My company often had a Hydrostatic Test Weight that was a short term load when they fill the pipes with water and pressure test the whole system.
b) These weights are way, way, way larger than the load that the piping system will ever see again. And, are never a long term load.

If the worst case "live load" for your structure were to be this type of hydrostatic test load, then it would make sense that you would would not include this weight in the majority of your design combinations. I still think you have to design for it... just with a lower safety factor and you don't include it with wind or seismic loads.

Note: We considered this load to be a temporary dead load, not a live load. But, this was US codes. Which, I should point out, also applies to the "Design of Structural Steel Pipe Racks".

 

[Ron247]

I have never had to design a pipe rack, but I would assume you still have to consider your actual project conditions. If the piping LL was sustained and long term, then I would assume you would include it in foundation design anyway.

 

[AskTooMuch]

Only 5% of pipe friction is used for the foundation at the braced bay. All pipe anchor should be included for foundation design.
The reasoning I was given is that pipe friction expands on opposite directions so they should cancel each other before going to the braced bay/foundation.

 

[HTURKAK]

Only 5% of pipe friction is used for the foundation at the braced bay. All pipe anchor should be included for foundation design.

TRUE..

pipe friction expands on opposite directions so they should cancel each other before going to the braced bay/foundation.

Not always true. Consider hot lines . The anchor forces developing shall be obtained from pipe stress analysis. I have been always provided anhor forces by pipe stress engineer. The 5% rule is for the friction forces developing at braced bay.

The OP should clarify the sentence ' ... 'interna client' standard saying that only 5% of live loads from piping (thermal, anchor etc) shall be taken to design foundations'

I searched the web for best practice and ask to AI. The following doc. (Steel Piperack Design ) suggested. There is a worked example for the newbies.
I have attached the same.

I will also suggest you to look Design of Structural Steel Pipe Racks (RICHARD M. DRAKE and ROBERT J. WALTER ) attached at my first post.