255.203 Instrument, control and sampling piping and components.

(a)This section applies to the design of instrument, control, and sampling piping and components. It does not apply to permanently closed systems, such as fluid-filled temperature-responsive devices.#

(b)All materials employed for pipe and components must be designed to meet the particular conditions of service and the following paragraphs:#

(1)Each takeoff connection and attaching boss, fitting, or adapter must be made of material suitable to withstand the maximum service pressure and temperature of the pipe or equipment to which it is attached, and be designed to satisfactorily withstand all stresses without failure by fatigue.#

(2)Except for takeoff lines that can be isolated from sources of pressure by other valving, a shut-off valve must be installed in each takeoff line as near as practicable to the point of takeoff. Blow-down valves must be installed where necessary.#

(3)Brass or copper material may not be used for metal temperatures greater than 400°F (204°C).#

(4)Pipe or components that may contain liquids must be protected by heating or other means from damage due to freezing.#

(5)Pipe or components in which liquids may accumulate must have drains or drips.#

(6)Pipe or components subject to clogging from solids or deposits must have suitable connections for cleaning.#

(7)The arrangement of pipe, components, and supports must provide safety under anticipated operating stresses.#

(8)Each joint between sections of pipe, and between pipe and valves or fittings, must be made in a manner suitable for the anticipated pressure and temperature condition. Slip type expansion joints may not be used. Expansion must be allowed for by providing flexibility within the system itself.#

(9)Each control line must be protected from anticipated causes of damage and must be designed and installed to prevent damage to any one control line from making both the regulator and the over-pressure protective device inoperative.#