WINTER 2013/14

Pumpkin Pi(pe) for New Years?

I have seen a lot of things get broken over the years; fire hydrants spouting geysers of water into the air, 20-inch water mains flooding whole neighborhoods, force mains spewing raw sewage, even whole bridges knocked off their foundations. Repairs, repairs, repairs! Earlier this month on construction for the Elliott Bay Seawall Project (EBSP), I had the opportunity to get a close up view on a type of repair I had not witnessed before.



A small leak developed in a nearly 60 year old gas main. The repair crew got right on it, excavated the main, and installed a clamp. Pretty standard stuff. Then came the interesting bit, at least for me. The next step was to install a steel casing over the clamp, referred to in the American Gas Association glossary as a “pumpkin”. A pumpkin is a field-fabricated steel sleeve that fully covers the clamp and is welded directly to the steel gas main. This way, the repair is reinforced and if the clamp leaks, which is always possible for a repair relying on some bolts and gaskets, the pumpkin helps with containment. Looks big and lumpy, hence the name – the same term is often used to refer to the housing of a vehicle differential.

The repair crew said this was an easy one on a straight section of pipe and sometimes they do the same thing to encase a tee, which is a tricky shape (think differential) to fabricate while down in a hole. They finished it up and it looked good. With some backfill and a patch on the road, odds are nobody will ever again see this repair. Always interesting to see something new..

Seeing this all take place made me wonder about how much natural gas escapes from pipelines in the U.S. every year. Check out this Scientific American post from August 2013.



Aging infrastructure is a huge challenge. We have to be willing to invest, or see the golden infrastructure “carriage” that makes our quality of life possible revert back into the proverbial pumpkin.