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Load Groups

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      ROD              CAPACITY                                                                                                                                           
GROUP SIZE kgf  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.

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.

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).

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.