Pipe clamps and ancillary items for support assemblies have been designed with standardized load carrying capacities that are compatible with metric hanger rods. These components are assigned to load groups; this simplifies selection and leads to cost-effective designs. For example, if all components in the load chain are selected as load group 5, the load carrying capacity of each item, and therefore of the whole assembly, will be 2280kgf; the load carrying capacity of an M24 hanger rod. Riser clamps and spreader beams are designed to sustain the standard load capacities on each rod.
Selection of components
The selection of beam attachments, hanger rods and rod attachments, spreader beams and other items which are not within the pipework’s thermal insulation (lagging) and are therefore not exposed to the pipe temperature is achieved simply be referring to the load capacity for
each load group and selecting the component accordingly. Load capacities for standard rod sizes are given below:
| Load Group | Rod Size | Capacity KGf | Capacity kN |
|---|---|---|---|
| 0 | M8 | 230 | 2.3 |
| 1 | M10 | 360 | 3.5 |
| 2 | M12 | 530 | 5.3 |
| 3 | M16 | 1010 | 9.9 |
| 4 | M20 | 1580 | 15.5 |
| 5 | M24 | 2280 | 22.4 |
| 6 | M30 | 3650 | 35.8 |
| 7 | M36 | 5340 | 52.4 |
| 8 | M42 | 7400 | 72.6 |
| 9 | M48 | 9650 | 94.6 |
| 10 | M56 | 13350 | 130.9 |
| 11 | M64 | 18000 | 176.5 |
| 12 | M72 | 23025 | 225.8 |
| 13 | M80 | 28125 | 275.8 |
The three bolt pipe clamps, riser clamps, and pipe bases are given a part number, which incorporates both the load group and the design temperature of the item concerned. For example:
| Part number | PC3 – 200 – 5 – 560 |
|---|---|
| PC3 | Three Bolt Pipe Clamp |
| 200 | 200mm Pipe Size |
| 5 | Load Group 5 |
| 560 | 560oC Design Temperature |
Because the pipe clamp is made from standard components, the load capacity at design temperature is likely to be slightly greater than the standard load capacity for the given load group. In the above example, the load capacity at 560oC is 2410kgf, whereas the standard load capacity is 2280kgf. Note also that load capacities are also given at temperatures above and below the design temperature for the clamp. Load capacities at intermediate temperatures can be obtained by interpolation. Do not select items for use at a temperature above the maximum temperature for which a load capacity is quoted for the item in question.
Is is important to note that in order to make the most efficient and cost effective selection of pipe clamp, riser clamp or pipe base, it may be necessary to consider several possible selections. If the design temperature of the clamp is in between the standard design temperatures, it may be possible to make a more cost effective selection either by considering the clamp for a lower load group or a lower temperature.
e.g. Pipe size = 250 N.B., Load = 1700kgf, Pipe temperature = 540oC
Consider the following three bolt pipe clamps:
| PC3-250-4-530 | Load capacity = 1673kgf (by interpolation) | No good |
| PC3-250-4-560 | Load capacity = 1830kgf | OK |
| PC3-250-5-530 | Load capacity = 2226kgf (by interpolation) | OK |
| PC3-250-5-560 | Load capacity = 2720kgf | OK |
Any of the last three clamps is an acceptable selection. If you simply select a clamp where the standard clamp design temperature exceeds the pipe temperature and the standard load group load capacity exceeds the actual load, you will select PC3-250-5-560, but this is not the most economic selection. In this example either PC3-250-4-560 or PC3-250-5-530 is a more efficient selection than PC3-250-5-560.
In designing and developing this range of pipe clamps and ancillary items, we at Pipe Supports Group have paid particular attention to compatibility of components across load groups. On the tabulations for pipe clamps and riser clamps, the compatible rod sizes are given. This is based on use with our standard pattern weldless eyenut, (or standard pattern clevis for flat plate type riser clamps).So when selecting components to make a pipe support assembly, you can choose a pipe clamp which has a different load group from the hanger rod. This situation may also arise when using variable effort supports, which have standard rod sizes to suit the maximum load on the spring.
All Pipe Supports Group’s standard pipe clamps and ancillaries are designed to withstand an increased short term load, such as occurs during hydrostatic test, up to twice the quoted load capacity for the item.
When using high temperature pipe chairs in conjunction with spreader beams, it may be desirable to specify load bearing insulation between the chair and the beam. Provided that the beam is not within the lagging, the temperature drop to the beam should mean that the beam itself will not be hot enough to significantly reduce its strength, but for reasons of personnel protection or thermal efficiency, load bearing insulation may be judged to be necessary.
Certain sizes of carbon steel pipe clamps are kept in stock to enable us to supply these items on very short lead times. The part numbers for these items are shown in bold in the tabulations in the Bergen Pipe Supports catalogue.