Dresser Coupling

I posted earlier about a leak in an old, somewhat rusty galvanized steel water line. I’ve since discovered “Dresser Couplings” which seem to be the solution. Our big concern is that the pipe is too weak to handle the pressure that the coupling will exert on the line, and crush/damage it more than it already is. Some questions for those in the know:1. what pressure does a water line typically carry?2. how can I make a test or educated guess as to whether the pipe can handle the pressure of the coupling? Any other thoughts? Here are links to two pictures I took. The first is before any repair. The second is a clamp my handyguy put on as a temporary fix. It is still dripping, but the majority of the leak has been stopped. Hope these links work…https://www.flickr.com/photos/82432034@N03/15797618779/https://www.flickr.com/photos/82432034@N03/15797896907/Dave

Dave,
A city water line will typically be in the 50 to 80 psi range, but there are many variations and it will vary with time-of-day and elevation within a given neighborhood.  Check the outside diameter or sirface of the pipe, if it is badly pitted or rusted you may have trouble getting any fitting to seal.  You may have to dig further up or down the line to get material good enough to seal.  Most pipe materials, including GI pipe, copper and PVC, are good for 150 psi and are available from any hardware store. 
Please note that if this is a drinking water line certain regulations and practices apply.  After the repair, you should thoroughly flush the system all the way to each affected end user.  While repairs are in progress, all kinds of things, including pathogens, can enter your system from the surrounding soil and cause illness.
Typically, GI pipe is good for 50 years in the soil depending on the pH of the soil.  High acid soil, which will have a pH less than 7.0, will shorten its life.  Also note that pH can vary every few feet feet so that if you dig a few feet either way you may find the pipe in real good shape.  Hope this helps.
Jim Allen

Yeah, it does Jim, thanks. Hard to know what “badly pitted or rusted” means. Oh well. The park is about 50 years old, and I"m sure this is original pipe.