Training and qualified personnel must assemble flanged joints in hazardous materials piping systems (see Appendix A of ASME PCC-1). Consideration should be given to establishing a finished joint examination process as part of the facility’s QA/QC assurance program. A leak or failure in a piping system can be a minor inconvenience for low-consequence fluids, or it can become a potential source of a process safety incident for higher-consequence fluids depending on…
the temperature, pressure, contents, and location of the piping. Piping in a petrochemical plant typically contains flammable fluids, acids, alkalis, toxic fluids, and other harmful fluids that would make leaks potentially hazardous to exposed personnel. Leaks in these kinds of piping systems can also have environmental consequences associated with their failure. Adequate inspection is a prerequisite for maintaining this type of piping in a safe, reliable condition.
Leakage can occur at flanged joints in piping systems for a variety of reasons, including corrosion, cracking, bolt tightness issues, gasket issues, and thermal expansion issues, especially in high-temperature services, during start-ups or shutdowns, and sometimes during normal operation. For these reasons, it is important that process plant practices include quality assurance/control procedures to ensure that flanged joints are properly assembled, inspected, and tested after maintenance activities where the joints have been disassembled and that the proper gaskets have been selected and installed. ASME PCC-1 is a useful standard for flange joint assembly practices.