Workshop manuals often advise that when removing fuel injectors, sump plugs, banjo fittings etc. that employ copper joint rings for sealing, the rings should be discarded and new rings fitted. The reason for this is that the copper hardens whilst it is being manipulated or worked and hardens with age, so there is no guarantee that an old and hard joint washer will provide an adequate seal.

If the joint ring is made of solid copper and not of the “Copandus” type such as cylinder head gaskets, which have a copper fibre sandwich; they can be reused after being annealed. Copper is annealed by heating to a red heat and then quenching in water, or left to cool in air. This softens the copper and makes it plastic and pliable so that it can be squeezed between the two components and form a seal.

The annealing process can be repeated as often as required and can be applied to any copper components including sheet copper. It is particularly useful when bending and forming the thick walled small bore copper piping used for fuel lines and lubricating oil pressure gauge sensing lines; as the annealed pipe is easier to bend and manipulate.

However, before heating the fuel or oil lines it is prudent to flush them through with water to remove all traces of oil. If the pipes are fitted with soft soldered unions, take care to protect them by wrapping them in a damp cloth otherwise the solder may melt allowing the unions to drop off! The copper pipes used in domestic plumbing can also be annealed in this manner, but be warned that because they are thin walled they will collapse, unless a former or bending spring is employed whilst bending them