A visual test or  inspection of a diving cylinder is made before a hydrostatic test is made. It is also done half way between the hydrostatic test cycle to verify the condition of the cylinder.

You may also want to read about the  Hydrostatic test next, or the taking the cylinder valve apart

Step 1 – Checking the threads

The first step is to inspect the threads for damage and to gauge them to see if they are in tolerance.  This is done with a pair of calibrated gauges called the “GO” and “NO-GO” gauge. Simply the GO should wind on or into the thread and the NO-GO should not. Threads are one of the major causes of cylinders to fail and usually it is due to maintenance by non-trained persons.

Gauging the valve thread
Gauging the valve thread
Gauging the outlet thread
Gauging the outlet thread
Gauging the cylinder thread
Gauging the cylinder thread

Step 2 – Visual Inspection

This is done externally and internally. Externally the boot is removed and the general condition of the cylinder is checked. Defective paint will not fail a cylinder. Deep rust marks and damage are the problem. Internal visual inspection is done by using a bright light and endoscope. This can even look back a the shoulder of the valve internally. Deep rust marks are the issue. Cylinders may have a light rusting over the inside. This is not a fail.

Looking inside a cylinder
Looking inside a cylinder