This document specifies requirements and test methods for unsintered polytetrafluorethylene (PTFE) tapes and polytetrafluorethylene (PTFE) strings (PTFE tapes or PTFE strings, for short) which are suitable for sealing threaded metallic joints as specified in EN 10226-1:2004. This document covers two classes of PTFE tapes and PTFE strings suitable for fine (F) and coarse (G) threads. The PTFE tapes and PTFE strings are used as sealing materials for metallic threaded joints in contact with 1st family gases (town gas), 2nd family gases (natural gas) and 3rd family gases (liquefied petroleum gases (LPG)) up to 500 kPa, up to 700 kPa for hot water of heating systems, and up to 20 kPa in gas appliances and their auxiliary equipment. The maximum working pressure covered in this document is 2000 kPa which is relevant to LPG storage. The temperature range is limited to −20 °C to 125 °C.