Copper pipe
| Copper pipe | |
| Type | Pipe material |
|---|---|
| Standard | BS EN 1057 |
| Used for | Hot and cold water, heating, gas |
| Jointing | Capillary soldered, compression, press-fit, push-fit |
| Characteristic failure | Pinhole from pitting corrosion |
Copper pipe has been the predominant material for hot and cold water and heating pipework in United Kingdom buildings since the mid-twentieth century. BS EN 1057 specifies seamless, round copper tubes for water and gas in sanitary and heating applications.[1] Copper is rigid, tolerant of heat, and carries leak noise efficiently, the last of which makes it the material acoustic detection works best on.
Grades and jointing[edit]
Tube is supplied in different wall thicknesses, in half-hard straight lengths for general installation and in annealed coils where bending without fittings is wanted, such as underground or beneath floors. Joints are made by capillary soldering, by compression, by press-fit using a tool and a sealed profile, or with push-fit fittings.
Each jointing method has a characteristic failure. Soldered joints fail where the joint was not fully drawn or the tube not properly cleaned. Compression joints fail where the olive was over- or under-tightened, or disturbed after being made. Both produce slow weeps rather than bursts, and both are frequently concealed.
Corrosion and pinhole leaks[edit]
The characteristic failure of copper tube itself is the pinhole, produced by pitting corrosion, which attacks a very small area of the wall rather than thinning it generally. A pinhole can pass a small continuous volume for a long period, which is why a copper system can lose pressure steadily with no visible damp for months.
Contributory factors include aggressive water chemistry, flux residues left inside the tube after soldering, high flow velocities in undersized pipe, and contact with certain building materials where tube is buried in plaster or screed without sleeving.
Detection characteristics[edit]
Copper's rigidity and density make it an efficient carrier of leak noise, so acoustic listening and correlation both perform well on it. That efficiency has a corollary: noise travels a long way along a copper run, so the loudest point on a surface can be some distance from the escape, and correlation or a second method is used to resolve position.
Copper is also detectable by conventional cable and pipe location equipment, which plastic pipe is not, so establishing the route of a buried copper run before excavating is generally straightforward.