Pipe clamps are used to clamp a pipe to a flat surface – traditionally of two styles, grip type (anchor) or Non-grip type (saddle / guide).
Grip or Anchor clamp: used when the pipe requires a tight clamping to restrict all movements. You can see in the image below how there is no gap between the pipe and the inner surface of the clamp.
Non-Grip or Saddle / guide clamp: used when it is desirable to have a looser fit to allow some movement. Movement could be thermal or mechanical (perhaps a vibration). Below is a representative image showing a gap between the pipe and the clamp. Realistically there would likely be contact at the top surface.
Traditionally pipe clamps were referenced by the size of the pipe they were clamping. So for example an engineer would ask for a pipe clamp for a 50 nominal bore pipe. No reference to the size of the clamp, thickness of the material, size of the holes etc.
Graphskill Sums (GSUMS) is the new way of labelling pipe clamps (Read More about GSUMS)
Hole centre to edge=B
So the code for a pipe clamp becomes: Graphskill SUMS=CLAMP/MATL/D-W*T-C-A-B-E
This clearly defines the physical dimensions of the clamp. Grip or non grip becomes meaningless as the engineer knows the outside diameter of the pipe. So for example, in the above example if the outside diameter of the pipe is 63 mm, the engineer could ask for Inside Diameter=D = 64 as above, or if they wanted a non-grip style they could ask for Inside Diameter=D = 68 (or whatever clearance they require)