A 1-part, silicone-based thread sealant for metal and plastic pipe systems carrying hot or cold water. LOCTITE SI 5331 is a low-strength, general-purpose thread sealant for locking and sealing plastic and metal fittings carrying hot or cold water, e.g. industrial and agricultural plastic water pipe systems or drainage systems. This acetoxy silicone-based medium-viscosity sealant cures at ambient temperature to form a flexible seal. It?s WRC listed, meets BS 6920 for potable water: 0706521 DVGW approval and is tested in accordance with EN 751-1; P1 NSF Reg. No.: 123620. Ideal for fittings carrying hot or cold water Works on metal or plastic WRC listed, meets BS 6920 for potable water: 0706521 P1 NSF Reg. No.: 123620 DVGW approval, tested in accordance with EN 751-1