fire water arrangement

RefreshingEng,
I'm sorry but I think your question is not clear. I do not know what you are trying to do. Please give more information. Even a sketch would help.

RefreshingEng,
I am posting the additional information you supplied to me so others can see it and also respond.

"I apologize for my poor English. Let me try to be clearer. It is a tank
farm with six tanks in a dike. Each tank must be cooled by its two-inch
pipe sprinkler system at the top. Instead of routing each tube with its own
support, the designer used the shell of the neighbor tank to get to another
tank. I think this arrangement is inadequate, because the protection of a
tank depends on the integrity of the other, but others do not agree with
me. I could not find any reference to the situation on the recommendations
of NFPA or FM. Could you help me? Thanks in advance.
Minoro"

Okay now I understand your situation.

My recommendation is as follows.
1.) DO NOT support the firewater lines to one tank on another tank.
2.) DO NOT run firewater lines above ground inside any dike area except for the riser right at the tank going to the actual spray header.
3.) The firewater lateral to each tank shall originate at a firewater main line outside the dike area and run independently, underground from the main header to the tank.
4.) Each lateral shall have it's own activation valve outside the dike area, a minimum distance from the main header. Do not group the activation valves all in one spot.

Something to consider:
Give some thought to adding a connection just downstream of each activation valve for an auxiliary connection for Pumper Truck tie-in of Foam Truck tie-in. This connection is just a TEE with a riser pipe in the underground line after the activation valve. This branch rises up to about 1 meter above grade then has an elbow and a capped-off fire hose connection. If pressure in the main is lost then a pumper truck can supply water or foam to the tank you want to save.