What is difference between an inspection and a test?

PI or PIAT?

Periodic Inspection (PI) is commonly referred to as a visual inspection

During a PI the cylinder is emptied, the boot is removed, the valve is removed, the outside of the cylinder is inspected to ensure it is safe to use, the inside is inspected for rust and other contaminants and the threads of the cylinder and valve are checked with certified gauges to ensure they are still adequate

Periodic Inspection and Test (PIAT) commonly referred to as a hydro

During a PIAT the first thing to be done is the Periodic Inspection the same as above.

Once this is done the cylinder if filled with water and first of pressurised to it's working pressure i.e. 232 or 300 bar typically and then pressurised to it's test pressure i.e. 348 or 450 bar, if the cylinder passes this then is has passed it's PIAT

The cylinder is then dried, re-assembled, stamped and labelled

For both a PI or PIAT your valve will be inspected and serviced

The threads on the valve will be inspected and tested with a gauge to ensure they are serviceable and the valve will be disassembled, cleaned and reassembled

What happens if something fails?

If either the cylinder or the valve fails rectification will have to take place before your equipment is returned to you, here are some scenarios

Cylinder passes & valve fails - a suitable valve will have to be fitted before your cylinder will be given back to you and the failed valve will be destroyed and not returned to you

Cylinder fails & valve passes - a replacement cylinder can be fitted to the valve, the cylinder will be destroyed and not returned to you

Cylinder fails & valve fails - time to buy a replacement valve and cylinder