Iowa Admin. Code r. 875-92.11
This rule applies to power boilers installed prior to July 1, 1983. Each steam outlet from a boiler, except safety valve and water-column connections, shall be fitted with a stop valve located as close as practicable to the boiler When a stop valve is so located that water can accumulate, ample drains shall be provided. The drainage shall be piped to a safe location and shall not be discharged on the top of the boiler or its setting. When boilers provided with manholes are connected to a common steam main, the steam connection from each boiler shall be fitted with two stop valves having an ample free-blowing drain between them. The discharge of the drain shall be piped clear of the boiler setting. The stop valves shall consist of one automatic nonreturn valve next to the boiler and a second valve of the outside screw and yoke type.
Iowa Admin. Code r. 875-92.11