Underground fire water pipeline for acid polluted soil

[panteo]

Our underground fire water pipeline is built some 27years ago on the site of three nitric acid plants. Due to acid spillage caused by leaky process pipeline over many years, the soil on the site is found to be heavily polluted by acid.
Many leak points found on the fire water pipeline these days. At present we are considering two options.
1)Replacing the pipeline with acid resistant material
2)Installing the pipeline above ground.

Regarding the later option, it caused controversy among coworkers that the fire water pipelines could be damaged by strong flame in the event of severe fire or explosion.
In this regard, please advise me on the options we are considering.

Many thanks in advance.

 

[abcmex]

One possible material is FRP. Check your local code to see if this is acceptable.
RGS

 

[quark]

In my view 27 years is a big and sufficient gap for a pipeline change. As abcmex suggested, you should check the local codes. Though I have experience with underground piping, I saw lot of above ground installations which I prefer as an engineer.

Indian code says the hydrant mains should be located 5meters away from the work areas along with stand posts but risers can be taken in. This way you can reduce damage to the hydrant system.

Regards,

 

[panteo]

I heard that some companies replaced the old steel underground piping with polyethylene pipe in the recent years. Also, the polyethylene pipe can withstand some 10bar and the price of 10inch(250A) PE pipe is some 28USD per one meter. Is PE pipe strong enough to the shock, like water hammer? If PE pipe is good for the firewater pipe, I'm considering to install a surge suppressor tank at both ends to prevent water hammer.

 

[kenvlach]

I suggest 304L stainless.

Believe you are in Korea, so it would be a good idea (& may be required by code) to bury the lines below maximum frost depth.

 

[abcmex]

In an acid polluted soil I would consider twice before to use 304L. Additionally stagnant water (like firefighting) make the application not easy :-(
You may even need to coat inside and outside if you use an metallic material. That is why some user (where acceptable by code) skip the hassle and use FRP or Plastic pipe.
RGS

 

[kenvlach]

If soil is heavily contaminated with other chemicals, especially halides (salts), FRP piping may be a better choice than SS.
However, considering that the existing piping has lasted 27 years and that the mean soil temperature is probably ~10^oC (alleviates SCC problems), w/o further evidence, I would still choose 304L.

panteo,
Any further description or analyses of the soil and/or firefighting water?