Sealcon NP-13-SS high quality stainless steel locking nuts are liquid tight to 150 psi. PG 13 / 13.5 Thread. Sold Individually. Made from 303 stainless steel. Sealcon PG 13 / 13.5 Stainless Steel Locking Nuts provide a NEMA 4x & 6 (IP 68 & 69K), 150 PSIG (10 bar) Liquid Tight Rating. They are ideally suited for marine applications, chemical plants, off shore rigs and food processing.