If natural offsets occur within the design of the pipework system, it may be possible to utilise this to take up thermal expansion by using the natural flexibility of the pipework. The tables below show the minimum length of offset required for steel and copper pipes subjected to thermal expansion. A system utilising an offset to take up expansion can be bracketed utilising most common types of brackets including drop rods, sliding and rolling supports. For more information, please see the first section of this product guide for more details.

Offset L = 0.1 √DX For Steel Pipes

Offset L = 0.06 √DX For Copper Pipes

L = Length of Offset in Metres X = Expansion in mm D = Outside Diameter of Pipe

Example of how cold draw can be used: 30m of 100NB Steel Pipework 82°C LTHW Δ = L x T x C of Δ Δ = 30 x 82 x 1.11 = 27.3mm Δ 27.3mm will require a 5.85m Offset (According to the table on the previous page)

Table Showing Single Offset For Steel Pipes (Without Cold Draw)
Expansion Pipe Nominal Bore
x 15nb 20nb 25nb 32nb 40nb 50nb 65nb 80nb 100nb 125nb 150nb 200nb
1 mm  0.46  0.52 0.58 0.65 0.69 0.77 0.87 0.94 1.09 1.18 1.29 1.48
3 mm 0.79 0.90 1.01 1.12 1.20 1.34 1.51 1.63 1.84 2.05 2.24 2.57
5 mm 1.02 1.16 1.30 1.45 1.55 1.73 1.95 2.11 2.39 2.65 2.89 3.32
10 mm 1.45 1.64 1.84 2.04 2.19 2.44 2.75 2.98 3.38 3.74 4.09 4.69
15 mm 1.77 2.01 2.25 2.51 2.68 3.00 3.38 3.65 4.13 4.58 5.01 5.74
20 mm 2.05 2.32 2.61 2.89 3.09 3.46 3.89 4.22 4.77 5.90 5.79 6.63
30 mm 2.51 2.84 3.19 3.54 3.79 4.24 4.77 5.16 5.85 6.48 7.09 8.12
40 mm 2.89 3.29 3.69 4.09 4.38 4.89 5.11 5.97 6.75 7.48 8.19 9.38
60 mm 3.55 4.02 4.02 5.01 5.36 6.00 6.75 7.31 8.27 9.17 10.04 11.49
80 mm 4.09 4.65 4.65 5.79 6.19 6.92 7.79 8.43 9.54 10.58 11.59 13.27
100 mm 4.58 5.19 5.19 6.48 6.92 7.75 8.71 9.43 10.67 11.83 12.96 14.83

 

Table Showing Single Offset For Copper Pipes (Without Cold Draw)
Expansion Pipe Nominal Bore
x 15nb 22nb 28nb 35nb 42nb 54nb 67nb 76nb 108nb 133nb 159nb 219nb
1 mm  0.23  0.28 0.32 0.35 0.39 0.44 0.49  0.52 0.62  0.69 0.76 0.89
3 mm 0.40 0.49 0.55 0.61 0.67 0.76 0.85 0.91 1.08 1.19 1.31 1.54
5 mm 0.52 0.63 0.71 0.79 0.87 0.99 1.09 1.17 1.39 1.55 1.69 1.99
10 mm 0.73 0.89 1.00 1.12 1.22 1.39 1.55 1.65 1.97 2.19 2.39 2.81
15 mm 0.90 1.09 1.23 1.37 1.52 1.71 1.90 2.02 2.41 2.68 2.93 3.44
20 mm 1.03 1.26 1.42 1.59 1.74 1.97 2.19 2.34 2.78 3.09 3.38 3.97
30 mm 1.28 1.54 1.74 1.94 2.12 2.41 2.69 2.86 3.42 3.79 4.14 4.86
40 mm 1.47 1.78 2.01 2.24 2.45 2.79 3.11 3.31 3.98 4.38 4.78 5.62
60 mm 1.80 2.18 2.46 2.75 3.01 3.42 3.80 4.05 4.83 5.36 5.86 6.88
80 mm 2.07 2.52 2.84 3.17 3.48 3.94 4.39 4.68 5.58 6.19 6.77 7.94
100 mm 2.32 2.81 3.17 3.55 3.89 4.41  4.91 5.23 6.24 6.92 7.56 8.88