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With awareness about copper’s benefits increasing, Gurmit Singh Arora, MD, Rajco Metal Industries Pvt Ltd, highlights the key technical aspects of copper plumbing.

Copper plumbing basically comprises of two aspects – Copper tubes and Copper fittings. At present copper tubes in our country are specified for water, gas and sanitation under BS2871.
 

An Indian Standard will be out very shortly. As some of us are aware, the British standards have now merged with the European specifications and copper pipes are now specified under the BS EN 1057.

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Similar to the A-B-C specifications for GI, wall thicknesses in copper is specified under Tables X, Y & Z. Table X is the medium quality used in 90% of installations worldwide. It gives the sizes, thickness and pressures for 15mm to 35mm OD.

As you can see from Table X, a 15mm tube which is equivalent to a ½” GI pipe has a working pressure of 841 PSI and a burst pressure of 3480 PSI. When subjected to such high pressures a copper tube will only burst above 3400 PSI.

Copper tubes are supplied in various qualities, hard, half hard or soft. Hard tubes are not recommended for bending. In fact, half hard tubes are also available for bending.

I can say so confidently with my company having already supplied over 10,00,000 m of bendable copper tubes of size 12mm OD x 0.6mm WT to the Mahanagar Gas project for its entire internal gas pipelines. It is highly impossible for somebody to hydraulically or pneumatically pressure test 100% of the tubes in 10’ lengths.

However, in lieu of this pressure test, Eddy Current testing has been prescribed as per ASTM E 243.

Tubes subjected to Eddy current are 100% leak-proof and any tube with any internal micro blow hole or defect which may rupture or leak is rejected by this test. It is therefore an absolute pre-requisite to specify copper tubes for plumbing only after this test.

Moreover, plasticity and ductility of material are only derived by proper chemical composition and use of right raw materials. The minimum percentage of copper in a tube is required to be 99.9% with a phosphorus level of 0.015% to 0.040%.

Elongation in half hard tubes is required to be minimum 30%. It is only then that the expansion on the outside surface and the contraction on the inside surface of a bent tube are uniform and free from wrinkles or kinks. It is very important for you to buy a proper quality product & specify eddy current tubes only.