Pipe labeling marking standards are not specifically outlined or defined by OSHA, but standard number 1910.261(a)(3)(i) notes the ASME's (ANSI) standard A13.1 as the recommended scheme for identification of pipe systems.
The ASME Standard for Pipe Identification is a widely used guideline in determining pipe identification requirements. The ASME A13.1-2007 editorial notes indicate that, "A13.1 is intended to establish a common system to assist in identification of hazardous materials conveyed in piping systems and their hazards when released in the environment." It goes on to identify that this scheme provides pipe system identification recommendations for industrial workplaces, power plants, commercial and institutional installations, and buildings used for public assembly.
ANSI/ASME A13.1 states that labels should be placed on pipes:
Scope Safety Services will perform pipe marking audits, then take the results of those audits and correct any deficiencies found to keep your employees safer and your facility in compliance.
We work with your subject matter experts to achieve accurate labeling of the pipes contents and magnitude of each pipe. We label everything from domestic water to ammonia piping. Being a partner in your safety program allows Scope Safety to work closely with your management team to achieve the best results for your facility and to provide value to your safety culture.