Gas Heat ESCO Practice Exam

How many threads should be cut on a 1/2" and 3/4" black iron pipe for fitting a natural gas furnace?

1. 8-10

2. 11-13

3. 14-16

4. 5-7

The correct answer is: 8-10

The correct answer for the number of threads to cut on a 1/2" and 3/4" black iron pipe when fitting a natural gas furnace is typically in the range of 11-13 threads. For fittings in natural gas applications, particularly with black iron pipe, it is important to ensure that enough threads are cut to allow for a secure and leak-free connection. This is critical for both safety and functionality, as gas leaks can be hazardous. The recommended amount of threads ensures that there is sufficient engagement with the fitting to create a tight seal. While it is necessary to follow specific guidelines and codes regarding pipe threading, fewer threads might not provide enough engagement for a secure connection, while excessively threading could run the risk of damaging the fitting or the pipe itself. Therefore, aiming for 11-13 threads is generally accepted to ensure proper assembly for a gas furnace installation.