Although cast iron gas mains have been in use for over 100 years, they are still very viable. When iron ages it forms a protective skin that prevents any further deterioration. Cut out a piece of cast iron pipe and look at the pipe wall cross section. You will see that it is usually as good as new under this top surface. Studies have shown that the cast iron pipes presently in use will last at least a further two hundred years. Engineers wish they could confidently say the same about any other type of pipe. The cost of replacing the many thousands of miles of all sizes of cast iron pipes throughout the country would be absolutely prohibitive and in most cases completely unnecessary.  

 

The problem with cast iron pipes is that there is a potential leakage point at every joint. The changeover to dry natural gas greatly increased the leakage of gas through these joints as it dried out all the joint packings. Some companies fogged with swellants such as monoethylene glycol (MEG) to try to resurrect the elasticity of the joint packings but most companies have done nothing to improve the quality of the joints.  

 

Over the years many methods of joint sealing have been tried with varying degrees of success. Leak clamps, shrink sleeves, epoxy wraps and internal patches have all been tried but proved to be temporary solutions at best.  The only two practical, economical solutions that have finally evolved are encapsulation and anaerobic sealing. > Read More