Most everyone is familiar with IIAR2, the American National Standard for Safe Design of Closed-Circuit Ammonia Refrigeration Systems. They will refer to it as the Recognized and Generally Accepted Good Engineering Practice (RAGAGEP) for our industry.
People often forget that IIAR2 is merely the RAGAGEP for the design of ammonia refrigeration systems, but not the installation. IIAR4-2020 is the current RAGAGEP for the installation of ammonia refrigeration systems. If we look through IIAR4, we find that it does, in fact, prohibit the practice of using sheet metal screws when installing insulation.
Section 8.1.11 states, “Screws, rivets, or any other jacket securement device that could pierce the underlying vapor retarder shall not be used. Only bands and seals shall be used to secure the jacketing.”