Connect 16 mm LDPE drip supply pipe to 1/2 inch US drip tubing
How to join 16 mm (0.63" OD) and 1/2" US (0.700" OD), and what stops it leaking.
Not a direct fit. Joining 16 mm LDPE drip supply pipe to 1/2 inch US drip tubing needs a 16 mm to 1/2 inch US drip adapter.
The part to buy
16 mm European pipe (0.63 inch outside) and US 1/2 inch tubing (0.700 inch outside) are both called half-inch but are different sizes, so a 16 mm fitting will not seal on US tubing. An adapter, or matching your fittings to one system, is the reliable fix.
The half-inch name is the trap. Measure the outside diameter: 16 mm is 0.63 inch, US half-inch is 0.700 inch. They do not share fittings.
Related connections
Sources: Drip fitting sizing and tubing compatibility, DripWorks · Barbed drip fitting sizing by tubing inner diameter, GardeningAsk · Drip tubing / fitting sizing guide, DripWorks