What’s the best way to tap a water main?
Pat Kline of Opflow has written a thorough article answering the question posed as the title of this blog posting. The article was published in Opflow‘s, May 2009 edition.
Below is a brief preview of the article.
QUESTION: I’ve seen many methods for connecting service lines to mains or laterals. Is there a rule of thumb to help me determine what to do in a given situation?
ANSWER: The method you choose to connect a service line to a main or lateral will affect whether you’ve made a tight, reliable connection that will give your customer years of satisfactory service. Let’s look at the factors involved one by one.
First, are you making the connection while the water main or lateral is left on or turned off? Dry taps, as they’re called when the main is shut down, are usually performed during main installation or other repairs. Dry taps are generally T-connections installed in the main or lateral. Wet taps, or hot taps, which use sleeves or saddles, are performed when the main or lateral is under pressure. It may seem as though dry taps would be the method of choice, but shutting the main down can cause water loss, increased potential for contamination, and lack-of-water or dirty-water complaints. Utilities perform wet taps most frequently, so that’s what we’ll talk about.
The article is broken down into the following sections. I will paraphrase each section.
A Valve By Any Other Name
There are different names for valves, but the end that connects to the main is the inlet, and the end that connects to the service line is the outlet.
The Art of Tapping
- The tapping tool is specific to the water main material.
- Ensure the valve stop threads match those of the tap.
- Use gaskets between the tapping machine and the saddle, and between the saddle and the pipe.
- Keep the outside of the pipe and the tapping drill disinfected and clean while tapping.
- Tap at 45 degrees in relation to the centerline of the pipe.
Turn, Turn, Turn,
Learn about the terminology involved in the details of pipe tapping.
- Thread pitch
- Major diameter | Minor diameter
- Pitch diameter
- Engagement
- Effective thread
