Can steel pipe be buried on NFPA?

[DavidCR]

We are planing some modifications to an existing power plant private fire mains, aprox. half of the system will be exposed and half buried.

We have plenty of steel pipe (ASTM A53B, A106B), good welders, etc. and we want to bury it using protective coatings (like Tek-rap´s). We can perform stress analisys with earthquake, etc.

In NFPA 24 (NFPA 7-1.1, 99 Edition) and others, I´ve seen that buried steel pipe is not allowed. Does somebody know why?

We have more problems installing PVC or iron pipes since we have to contract the designs and labor to others.

Any comment on using buried steel pipe for fire applications will be appreciated.

Thanks in advance.

 

[kenvlach]

My strong hunch is regulators that like inspecting visible piping, i.e., don't like buried pipe which could corrode undetected.

 

[Slowzuki]

Steel pipe corrodes very quickly underground so is not reliable enough for fire protection. Wraps and such have not been acceptted yet as acceptable forms of protection most likely due to the care needed during installation.

Some powerplants here run the pipe in tunnels on site to get around this.

Otherwise it is high pressure concrete, plastic or ductile iron!

 

[humanfactoreng123]

You can use stainless steel, but not steel without
cathodic protection due to the corresive effect of
the earth. Here is a typical fire hydrant equipment
description:

Century and B-50-B Fire Hydrants
(ULC Listed, FM Approved, meets AWWA C502)

High Pressure Hydrants
Where service line pressures exceed the 150 psi (10 bar) working pressure limit of AWWA type hydrants, a Canada Valve High Pressure hydrant may be utilized. This hydrant has a rated working pressure of 250 psi (17 bar).

Salt Water Service Hydrants
For salt water service or other corrosive conditions, hydrants can be supplied with stainless steel and special alloy bronze components.

Non-Draining Hydrants
Where water table conditions would prevent proper drainage of the hydrant barrel, hydrants without drain ports can be supplied. This arrangement prevents entry of ground water into the hydrant barrel, however, hydrant barrel should be pumped out after each use. Note that standard hydrants can be easily converted to non-drainage type after installation.

Hydrants with Special Outlet Configuration
For all models of hydrant, the standard outlet configurations is two male hose outlets (2-1/2&quot or two male hose (2-1/2&quot and one male pumper (4-1/2&quot outlet. For special applications, other arrangements (three hose outlets, female threaded outlets, etc.) can be provided.

"Storz" Type Pumper Outlet
For quick connection of "Storz" type hose connector directly to a hydrant, a "Storz" type outlet can be provided. The fire hydrant "Storz" type outlet is manufactured from a bronze alloy for corrosion resistance, and utilizes a metal sealing face rather than a rubber gasket.

Monitor Hydrants
To facilitate mounting a monitor nozzle, B-50-BM hydrants are available with a flanged outlet elbow on the upper barrel. Flange is normally supplied to ANSI specifications for 3" - 125 lbs. flanges


JOHN HEYWOOD, P.E., CSP
SENIOR SAFETY ENGINEER
Saint Louis, Missouri 63125