Pipe joint
Press fittings — flame-free cold pressing
Joining copper, stainless steel or PEX with an O-ring and a press tool
Press fitting is a fast, flame-free jointing method in which an O-ring-sealed fitting is pressed onto the pipe with an electro-hydraulic press tool. The mechanical strength and tightness are achieved ONLY when the specified insertion depth and the correct press profile are observed. The guide covers cutting, deburring, insertion marking, pressing and inspection.
Choose one matching system
Use fitting, press jaw/sling and press profile from the same system according to the manufacturer's instructions — the profiles (e.g. V, M, TH) must not be mixed. Check that the fitting's O-ring suits the medium (drinking water, heating, gas) and the pressure/temperature class.
Cut the pipe square
Cut the pipe so that the cut is clean and square. A skewed cut means the pipe does not reach the insertion depth all the way round and can damage the O-ring on insertion.
Deburr inside and outside
Deburr the pipe end carefully both inside and outside. A sharp burr can cut or displace the O-ring when the pipe is pushed into the fitting — and a leaking O-ring is the most common fault with press fittings.
Check the O-ring
Check that the O-ring sits correctly in its groove and is clean and undamaged. Remove dirt and swarf. Some systems allow light lubrication of the pipe end with an approved lubricant — follow the manufacturer's instructions.
Mark the insertion depth on the pipe
Measure the specified insertion depth for the dimension and put a mark on the pipe. Systems with plain pipe ends must be marked with an insertion depth mark before jointing. The mark is your check that the pipe is fully home — and later that the joint is correct.
Push the pipe fully home
Push the pipe into the fitting until it reaches the bottom — the marking must be at the edge of the fitting. The mechanical strength is only achieved when the specified insertion depth is maintained all the way round.
Press the joint square
Place the press jaw square around the fitting's press bead and carry out the pressing with the tool running through the whole cycle. Do not move the tool until the press cycle is complete. Make sure there is enough room for the jaw before you install.
Check after pressing
After pressing, the insertion depth marking must be visible right next to the press bead, and the deviation from the specified insertion depth must be no more than approx. 10 %. If the marking has disappeared inside or is too far out, the joint is not correct.
Max. deviation~10 % of the insertion depthFind unpressed joints when filling
Many systems have a feature that makes a forgotten (unpressed) joint leak at low test pressure, so it is revealed during filling/pressure check. Go systematically through all joints so none is left unpressed. Then carry out the full pressure test as normal.
Flame-free method — no hot work or fire watch, but only one jointing system at a time.
Source
Based on the press-fitting technical handbook and Geberit Mapress and Viega installation instructions (deburring, insertion depth marking, max. 10 % deviation, unpressed indication); pipes according to DIN EN 1057. The worktree product range «Pressfitting».