chemical plant design 3

[QUEENCHEM]

Dear all, we are doing design of industrial chem plants and we would like to know your opinion about conceptual design of pipe-racks and structure: is it better to employ steel or concrete (pls. consider fire proofing as mandatory)?

 

[Montemayor]

QUINNCHEM:

I've used both. Since this is only conceptual, consider the following:

1. Concrete's fire resistance is countered by its inherently weak tensile strength -it practically has none. You have to employ it reinforced with rebar. Otherwise, any lateral force or blow would bring the pipe racks down on your head.

2. Since you have to add steel, isn't this approaching the same thing as H-beams coated with concrete for fire resistance? ---except that the reinforced concrete requires more labor and time. Plus, you can't weld or retrofit onto the concrete design; what you build is pretty well what you have to stay with.

3. When you say "beter" what exactly do you mean? Better is not an engineering term unless it is qualified. Do you mean economically? Safety wise? Operational wise? More practical? If your you or your relatives own a concrete plant, I guess that would be "better" also - right?

As I've said, I've employed concrete pipe supports - in overseas installations where labor was relatively cheap. I inherited them in existing plants and I found them to be deficient in design and lacking in flexibility. I've never proposed them in plants I've designed.

 

[SmartEngineer]

From past experience, the project I was working with had contacted consultant civil department to advice either concrete or steel pipe racks is better for the project cost and schedule.
You should consider the following factors in your selection:
- Cost as the market is currently hot and the steel is much expensive than concrete
- Schedule of the project,
- Overall cost, i.e labor, materials, logistics...etc

I have seen both applications in some plants and there are different reasons of their selection.

Hope this would help
Cheers

 

[QUEENCHEM]

Dear all,

many thanks thanks for your helpful suggestions 1nd point of view!
I just would like to specify some issues:
- acc. to european law for safety we are obliged to apply fireproofing if the piping laying on the pipe-rack are in service with flammable material
- of course we are interested to offer the most economical convenient solution to our client, which has anyhow to guarantee the technical requirements of good engineering practice
- the project schedule is year 2007 (prefabrication and erection)

I will appreciate any further opinion about this theme.

Have a nice day!