Not all threads are cut in the same direction. Left hand and right hand threads can be misidentified at first sight. A simple visual check can help avoid any costly missteps.
While standing at the face of the connection, look down on the thread. If the thread groove appears to rise up from the bottom left to the right – it is a right handed thread. If the threads rise up from the bottom right to the top left – it is a left handed thread. Looking at the last tool marks may also show the same attributes and help with easier identification.
If there as any uncertainty after this, a physical check with a basic form profile can alleviate any doubt. Sweep the profile to the right. If the sweep takes the profile toward the face of the connection near you, it’s a left-handed connection. If the sweep takes it away from the face or towards the shoulder/body of the pipe, you have a right-handed connection.