Standard pipe clips are usually either 2 bolt clips or 3 bolt clips. Basically they are two halves that are bolted together around a pipe.
2 Bolt Pipe Clip
A 2 bolt pipe clip comes in two halves, and as can be seen in the diagram, has two bolts, one either side of the pipe to join the two halves together
These are typically used with a hanger rod to suspend the pipe. However they can also be used with a shoe or base plate.
3 Bolt Pipe Clip
Like the 2 bolt pipe clip, the 3 bolt pipe clip comes in two halves, as can be seen in the diagram. However it has three bolts, one either side of the pipe, and one towards the end of an extended arm to join the two halves together
These would often be used where the pipe is perhaps insulated, so that the hanger rod would be outside of the insulation
Traditionally pipe clips were referenced by the size of the pipe they were clamping. So for example an engineer would ask for a pipe clip for a 50 nominal bore pipe. No reference to the size of the clip, thickness of the material, size of the holes etc.
Graphskill Sums (GSUMS) is the new way of labelling pipe clips (Read More about GSUMS)
Hole centre to Edge=G
Gap Between halves=R
Bolt Diameter Size=M
So the code for the pipe clamp becomes: Graphskill SUMS=CLIPS/MATERIAL/D-W*T-P-G-R-M
Example : CLIPS/T304/224-65*12-320-36-12-M24
This clearly defines the physical dimensions of the clip.