Marking – What Is Piping: All about Piping Engineering

Industrial Pipe Color Coding and Pipe markings are used to differentiate and keep track of fluids transported inside the pipes; Mainly to identify pipes carrying hazardous fluids. While in a plant, most of you must have seen in operating process plants that pipes are colored in various colors. Importance of piping color coding There are two main reasons behind industrial pipe color coding and pipe marking: To allow the metallurgy of each pipe spool to be easily identified in the warehouse before erectionProcess and utility piping can be properly and clearly identified for use by plant personnel So pipe color coding will help in identifying the Piping components shipped individually to the construction site and Material identification shall not be required for pipe spools that have been verified by the shop and have mark piece numbers associated with them. Permanent color pipe service markers shall be used for process and utility services. Fabricator shall provide service markers for spools produced. Placing the marker on the spool shall be done after piping has been installed, coated, or insulated if required. Pipe Color Coding and Pipe Marking of Systems Pipe Material Color Coding Material color coding is developed to differentiate between various grades or specifications of materials.Color markings are assigned on the basis of nominal chemical compositions.Location of pipe marking shall be as follows:Pipe shall be marked with, for example, paint, dye, or tapes for its full lengthFlanges shall be banded (Refer Fig. 1) on the back of the flange at the intersection of the back face and the hubFittings shall be stripped from bevel to bevelMiscellaneous material shall be color marked so as to provide proper identityThe paint shall not cover welded surfaces, heat marks, or any other identification Fig. 1: Figure showing Pipe Color Band Locations Pipe Service Markers Permanent color pipe service markers shall be used for all process and utility piping systems within the plant. Piping systems for pipe color coding shall include utility pipes of any kind and, in addition, fittings, valves, and pipe coverings. Piping systems shall be painted a neutral background color, for example, aluminum or grey, which shall not detract from the high visibility of the colors and lettering of the service markers. Permanent color markers for piping systems shall be placed at the battery limit and at vertical risers at utility stations. Service markers shall be applied close to valves or flanges, and adjacent to changes in direction, branches, and where pipes pass over or through walls, floors, fences, or roads, and on straight pipe runs, sufficient for identification. A service marker in English shall be used as the primary and explicit means of identification for the contents of all aboveground piping. Positive identification of the contents of a piping system shall be by lettered legend giving the name of the contents in full or abbreviated form. Arrows shall be used to indicate the direction of flow. Additional details, for example, temperature or pressure, shall be added as necessary to highlight the degree of hazard. Shutdown, emergency, or car-sealed valves shall be labeled with P&ID and valve numbers and any descriptive labeling needed to permit easy identification. Firewater system sectionalizing block valves shall be identified by their firewater system identification number. Contrast shall be provided between the color field and legend for readability. For identification of materials in pipes of less than 3/4 inch (19 mm) in diameter, and for valve and fitting identification, the use of a permanently legible tag is recommended. The size of the service marker letters shall neither be less than 13 mm nor be greater than 89 mm, varying in size depending on the outside diameter of the pipe. For piping 2 inch NPS and smaller running between equipment, where the total length is less than 15 m, no pipe marking shall be necessary. For piping on pipe racks, pipe service marking shall be oriented in a way that it is visible from grade level and from any nearby platform. The color of the service marker letters shall be black or white, whichever provides the greater contrast to the background color. Pipe markings shall be clearly visible. Where pipelines are located above or below the normal line of vision, the lettering shall be placed below or above the horizontal centreline of the pipe. Pipe Marking materials for stainless steel and nickel alloy piping shall not contain any harmful substances, for example, chlorides, fluorides, sulfur, and low melting point metals. Pipe Color Coding and Marking Execution Process Surface Preparation: Surfaces to be color-coded or marked shall be free from oil, grease, dirt, and other surface contaminants that might be detrimental to the adhesion of the paint used for color coding and marking. Application of Pipe Color Coding and Pipe Marking Whenever color coding or marking paint is to be applied to a primed surface, the primer shall be dried completely before the color coding or marking paint is applied.Color coding, marking, and identification paint shall be applied to dry, clean surfaces in accordance with the manufacturer’s instructions.Unless otherwise recommended by the manufacturer, color coding and marking shall not be undertaken when the ambient temperature is less than 10 °C (50 °F), or the relative humidity is more than 90 percent.Color coding and marking paint shall be applied in 1 coat. Industrial Color Code Standards The following codes and standards as guidance for industrial pipe color codes: PFI ES-22 – Recommended Practice for Color Coding of Piping MaterialsIS 2379 – Pipelines Identification Colour CodeISO 14726- Color Coding for Marine ServicesBS 1710 – Specification for Identification of Pipelines and ServicesASME/ANSI A13.1 – Scheme for the Identification of Piping Systems Different codes mentioned above use different philosophy with respect to pipe color coding and pipe marking systems. For example, As per ASME A13.1 the following pipe color code system is followed: Fig. 2: Pipe Color Codes