• Gas and water approved: conforms to BS EN 751-1 for 1st, 2nd and 3rd family gases, the jointing compound standard BS 6891 requires on UK domestic gas pipework
• WRAS Approved for potable water: approval 2305553 covers hot and cold water services up to 85°C once fully cured for 24 hours at 23°C
• Medium strength and removable: cures hard to lock and seal the joint yet still comes apart with standard hand tools, so fittings can be repositioned or serviced later
• Wide working range: seals threaded metal joints in brass, steel and stainless from -50°C to +150°C and fills thread gaps up to 0.20 mm
• Cleaner than tape or hemp: a thixotropic liquid applied straight from the nozzle that resists run-off, so there are no loose fibres or trailing tape ends to trim
• Built for real systems: resists fuels, oils, coolants and hydraulic fluids on gas, LPG, heating, compressed air and hot and cold water threaded pipework

GFS 543 is a medium-strength anaerobic pipe thread sealant for threaded metal joints in gas, LPG, heating and water systems. Supplied in a 50 ml bottle with a precision nozzle, it cures in the absence of air between close-fitting metal threads and forms a seal that resists shock, vibration and pressure. WHY THE STANDARDS MATTER BS 6891, the British Standard for domestic gas installation pipework up to 35 mm, requires jointing compounds to conform to BS EN 751-1, -2 or -3. GFS 543 is an anaerobic jointing compound conforming to BS EN 751-1, covering 1st, 2nd and 3rd family gases - town gas, natural gas and LPG vapour - and hot water heating systems. It also holds WRAS approval 2305553 for contact with wholesome water, up to 85C when cured 24 hours at 23C. SPECIFICATION Colour: blue. Anaerobic methacrylate, single component, solvent free. Medium strength - locks and seals, still releases with hand tools. Temperature range -50C to +150C. Maximum thread gap 0.20 mm. Size 50 ml. WHERE IT FITS Brass, steel, stainless steel and other metal threaded pipes and fittings. Gas and LPG service connections, central heating, boiler and radiator valve tails, compressed air, hydraulic systems, hot and cold water. Metal threads only - not for plastic threads, and BS 6891 advises jointing compound is not used together with PTFE materials. HOW TO USE Clean and dry both threads. Apply a 360 degree bead to the male thread, leaving the first thread clear. Assemble, tighten to the fitting maker's recommendation, wipe away excess. Handling strength in a few hours; allow 24 hours at 23C for full cure. To disassemble use hand tools; if stubborn, apply local heat and separate while warm. IN THE BOX 1 x GFS 543 Pipe Sealant, 50 ml. SAFETY Contains methacrylate ester. May cause an allergic skin reaction and serious eye irritation. Wear gloves and eye protection and consult the safety data sheet before use. Keep out of reach of children.