The insulating joints when and why

PROCHIND in the fight against corrosion of metal pipes

About 20% of world’s annual steel production is destroyed by corrosion which affects, among other things, the pipes used for the transportation and distribution of gas, water and petroleum products.

The corrosive attacks that develop on said pipes, cutlery for the most part in the ground, can cause the following serious inconvenients:

• conveyed-product leaks, at times accompanied by explosions and fires when gas or other hydrocarbons are involved;

• contaminations of water being conveyed in pipelines;

• pollution of the soil, streams, waterways and shallow or deepwater estuaries;

• interruption to services resulting in high equipment replacement and installation costs;

• reducing the pressure rating of the opaline as a result of deterioration caused by corrosion.

These costly inconvenients and damages could be avoided if pipelines were provided with effective cathodic protection. However, cathodic protection could only be effective if the pipelines were:

• provided with a high-quality insulating coating throughout;

• not in physical contact with unprotected foreign metal structures, including all related works which contain, protect weigh down, anchor and support them;

• electrically insulated from those parts that constitute a low-resistance earthing as well as from their sections or equipment which need not be or cannot be cathodically protected.

The electrical insulation on pipelines is achieved by means of special fittings referred to as insulating joints (or spigot insulating joints), to which they require a hydraulic seal and a resistance to mechanical and thermal stresses at least equal to those of the pipe in which they will be inserted.

The various types of PROCHIND® insulating joints need neither maintenance nor replacement during the entire working life of the pipeline on which they are installed. This provides substantial economic advantages since it allows for great reduction both in installation and running costs.

In fact, whilst insulating flange joints have to be installed above-ground or within a water proof inspection pit, PROCHIND® insulating joints can be buried in the soil.

In such a case, they have to be provided with an appropriate external insulating coating or wrapped with suitable tape system.