• Thread gauges measure the thread characteristics on pipes and screws.Water Pipe with red handle image by Olga Sapegina from Fotolia.com
  
  A thread gauge is designed to help builders and plumbers measure the threading on pipes. Pipe threading is the groove pattern cut into the pipe that allows one end to be screwed into another socket or valve. The threading patterns are both pieces must match, so pipe threading is strictly standardized. The thread gauge helps measure the threading and make sure that it is correctly cut.
  
  

Pitch

• The pitch is how much the threading inclines as it works down the pipe or screw. The wider the pitch, the more ground the thread will cover with each circle. Pitch is one of the most common ways to measure a threading and immediately classify it as a specific standard that will fit with other threads of the same size.
  
  

Diameter

• Diameter refers to the distance from one end of the thread to the other across the pipe. For pipes where the threading is on the outside, this is known as major diameter, since the extreme edges are measured using the thread gauge. For pipes where the threading is on the inside, the minor diameter is measured.
  
  

Size

• There are many size measurements that thread gauges can take. One of the most common is the size of the thread itself--how wide the thread ridge is, how deeply it is cut into the metal, and what shape it takes as it moves from the base to the tip.
  
  

Checking Shafts and Holes

• There is a special type of thread gauge known as the "go/no-go" gauge, typically only a rubber ring or cylinder, without the more complicated measuring features of other gauges. Users check shafts (if the threading is on the outside) and holes (if it is on the inside) using these gauges to quickly see if they will fit other parts. In this case, thread uniformity is assumed, and the user just wants to check the dimensions of the pipe to see if it will be a reliable fit.