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Condensate Recovery

Sizing Condensate Return Lines

A guide to sizing condensate lines to and from steam traps, including examples and calculations using the condensate pipe sizing chart.

Sizing Condensate Return Lines

The four main types of condensate line, as mentioned in Module 14.2, are shown in Table 14.3.1:

Table 14.3.1 The four basic types of condensate line

Type of condensate line Condensate line is sized to carry the following
Drain lines to trap Condensate
Discharge lines from traps Flash steam
Common return lines Flash steam
Pumped return lines Condensate

Sizing of all condensate lines is a function of:

  • Pressure - The difference in pressure between one end of the pipe and the other. This pressure difference may either promote flow, or cause some of the condensate to flash to steam.
  • Quantity - The amount of condensate to be handled.
  • Condition - Is the condensate predominately liquid or flash steam?

With the exception of pumped return lines which will be discussed in Module 14.4, the other three main types of condensate line and their sizing, will be covered in this Module.

Sizing drain lines to traps

It should not be assumed that the drain line (and trap) should be the same size as the plant outlet connection. The plant may operate at a number of different operating pressures and flowrates, especially when it is temperature controlled. However, once the trap has been correctly sized, it is usually the case that the drain line will be the same size as the trap inlet connection, (see Figure 14.3.1).

14.3.1 The drain line should not be sized on the plant connection

Regarding the conditions inside the drain line, as there is no significant pressure drop between the plant and the trap, no flash steam is present in the pipe, and it can be sized to carry condensate only.

When sizing the drain line, the following will need consideration:

  • The condensing rate of the equipment being drained during full-load.
  • The condensing rate of the equipment at start-up.

At plant start-up, the condensing rate can be up to three times the running load – this is where the temperature difference between the steam and colder product is at its maximum.

The drain line, trap, and discharge line also have to carry the air that is displaced by the incoming steam during this time.

The sizing routine for the steam trap will have to consider both of these variables, however, in general:

  • For steam mains drainage, the condensate load for each drain trap is typically 1% of the steam capacity of the main based on drain points at 50 m intervals, and with good insulation.

For most drain points, sizing the trap to pass twice the running load at the working pressure (minus any backpressure) will allow it to cope with the start-up load.

  • On constant steam pressure processes such as presses, ironers, unit heaters, radiant panels and boiling pans, sizing the traps on approximately twice the running load at the working pressure (less any backpressure) will provide sufficient capacity to cope with the start-up load.
  • On temperature controlled applications, the steam pressure, the plant turndown, the set temperature and steam trap location need to be considered in detail, and the trap needs to be sized to cater for both the full and minimum load conditions. If these conditions are not known it is recommended that the steam trap be sized on 3 x the running load at the running differential pressure. This should satisfy the start-up condition and provide proper drainage at minimum loads.

When the trap is sized in this way, it will also cater for the start-up load. Consequently, if the drain line to the trap is sized on the trap size, it will never be undersized.

For practical purposes, where the drain line is less than 10 m, it can be the same pipe size as the steam trap selected for the application. Drain lines less than 10 m long can also be checked against Appendix 14.3.1 and a pipe size should be selected which results in a pressure loss at maximum flowrate of not more than 200 Pa per metre length, and a velocity not greater than 1.5 m/s. Table 14.3.2 is an extract from Appendix 14.3.1.

On longer drain lines (over 10 m), the pressure loss at maximum flowrate should not be more than 100 Pa/m, and a velocity not greater than 1 m/s.

Table 14.3.2 Flow of water in heavy steel pipes

Flowrate Capacity kg/h
Pipe size Ø 15
mm
20
mm
25
mm
32
mm
40
mm
50
mm
65
mm
80
mm
100
mm
Pa/m mbar/m <0.15 m/ s 0.15 m/s 0.3 m/s
90 0.9 173 403 745 1627 2488 4716 9612 14940 30240 1.0 m/s
92.5 0.925 176 407 756 1652 2524 4788 9756 15156 30672
95 0.95 176 414 767 1678 2560 4860 9900 15372 31104
97.5 0.975 180 421 778 1699 2596 4932 10044 15552 31500
100 1 184 425 788 1724 2632 5004 10152 15768 31932
120 1.2 202 472 871 1897 2898 5508 11196 17352 35100
140 1.4 220 511 943 2059 3143 5976 12132 18792 38160
160 1.6 234 547 1015 2210 3373 6408 12996 20160 40680
180 1.8 252 583 1080 2354 3589 6804 13824 21420 43200 1.5 m/s
200 2 266 619 1141 2488 3780 7200 14580 22644 45720
220 2.2 281 652 1202 2617 3996 7560 15336 23760 47880
240 2.4 288 680 1256 2740 4176 7920 16056 24876 50400
260 2.6 306 713 1310 2855 4356 8244 16740 25920 52200
280 2.8 317 742 1364 2970 4536 8568 17388 26928 54360
300 3 331 767 1415 3078 4680 8892 18000 27900 56160

Example 14.3.1

An item of plant, using steam at constant pressure, condenses 470 kg of steam an hour at full-load. The pipework between the plant item and the steam trap has an equivalent length of 2 m.

Determine the size of pipe to be used.

Revised load allowing for start-up = 470 kg /h x 2 = 940 kg /h.

As the pipe length is less than 10 metres, the maximum allowable pressure drop is 200 Pa/m.

Using Table 14.3.1, by looking across from 200 Pa/m it can be seen that a 25 mm pipe has a capacity of 1 141 kg /h, and would therefore be suitable for the expected starting load of 940 kg /h.

Checking further up the 25 mm column, it can be seen that a flowrate of 940 kg /h will incur an actual pressure drop of just less than 140 Pa/m flowing through a 25 mm pipe.

Sizing discharge lines from traps

The section of pipeline downstream of the trap will carry both condensate and flash steam at the same pressure and temperature. This is referred to as two-phase flow, and the mixture of liquid and vapour will have the characteristics of both steam and water in proportion to how much of each is present. Consider the following example.

Example 14.3.2

An item of plant uses steam at a constant 4 bar g pressure. A mechanical steam trap is fitted, and condensate at saturation temperature is discharged into a condensate main working at 0.5 bar g.

Determine the proportions by mass, and by volume, of water and steam in the condensate main.

Part 1 - Determine the proportions by mass

From steam tables:

Example 14.3.2 with Equation 2.2.5

Clearly, if 7.9% is flashing to steam, the remaining 100 – 7.9 = 92.1% of the initial mass flow will remain as water.

Part 2 - Determine the proportions by volume

Based on an initial mass of 1 kg of condensate discharged at 4 bar g saturation temperature, the mass of flash steam is 0.079 kg and the mass of condensate is 0.921 kg (established from Part 1).

Water:

The density of saturated water at 0.5 bar g is 950 kg/m3,


Appendix 14.3.3a

From this, it follows that the two-phase fluid in the trap discharge line will have much more in common with steam than water, and it is sensible to size on reasonable steam velocities rather than use the relatively small volume of condensate as the basis for calculation. If lines are undersized, the flash steam velocity and backpressure will increase, which can cause waterhammer, reduce the trap capacity, and flood the process.

Steam lines are sized with attention to maximum velocities. Dry saturated steam should travel no faster than 40 m/s. Wet steam should travel somewhat slower (15 to 20 m/s) as it carries moisture which can otherwise have an erosive and damaging effect on fittings and valves.

Trap discharge lines can be regarded as steam lines carrying very wet steam, and should be sized on similarly low velocities.

Condensate discharge lines from traps are notoriously more difficult to size than steam lines due to the two-phase flow characteristic. In practice, it is impossible (and often unnecessary) to determine the exact condition of the fluid inside the pipe.

Although the amount of flash steam produced (see Figure 14.3.2) is related to the pressure difference across the trap, other factors will also have an effect.

14.3.2 Quantity of flash steam graph

Factors having a bearing on two-phase flow inside a pipe, include:

  • If the condensate on the upstream side of the trap is cooler than the saturation temperature (for example: a thermostatic steam trap is used), the amount of flash steam after the trap is reduced. This can reduce the size of the line required.
  • If the line slopes down from the trap to its termination, the slope will have an effect on the flow of condensate, but to what magnitude, and how can this be quantified?
  • On longer lines, radiation losses from the line may condense some of the flash steam, reducing its volume and velocity, and there may be a case for reducing the line size. But at what point should it be reduced and by how much?
  • If the discharge line lifts up to an overhead return line, there will be times when the lifting line will be full of cool condensate, and times when flash steam from the trap may evaporate some or all of this condensate. Should the rising discharge line be sized on flash steam velocity or the quantity of condensate?
  • Most processes operate some way below their full-load condition for most of their running cycle, which reduces flash steam for most of the time. The question therefore arises: is there a need for the system to be sized on the full-load condition, if the equipment permanently runs at a lower running load?
  • On temperature controlled plant, the pressure differential across the trap will itself change depending on the heat load. This will affect the amount of flash steam produced in the line.

Recommendations on trap discharge lines

Because of the number of variables, an exact calculation of line size would be complex and probably inaccurate. Experience has shown that if trap discharge lines are sized on flash steam velocities of 15 to 20 m/s, and certain recommendations are adhered to, few problems will arise.

Recommendations:

  1. Correctly sized trap discharge lines which slope in the direction of flow and are open-ended or vented at a receiver, will be non-flooded and allow flash steam to pass unhindered above the condensate (Figure 14.3.3). A minimum slope of 1 in 70 (150 mm drop every 10 m) is recommended. A simple visual check will usually confirm if the line is sloping - if no slope is apparent it is not sloping enough!
14.3.3 Discharge line sloping 1:70 in the direction of flow

2. If it is unavoidable, non-pumped rising lines (Figure 14.3.4) should be kept as short as possible and fitted with a non-return valve to stop condensate falling back down to the trap. Risers should discharge into the top of overhead return lines. This stops condensate draining back into the riser from the return main after the trap has discharged, to assist the easy passage of flash steam up the riser.

14.3.4 Keep rising lines short and connect to the top of return lines

It is sensible to consider using a slightly larger riser, which will produce a lower flash steam velocity.

This will reduce the risk of waterhammer and noise caused by steam trying to force a path through the liquid condensate in the riser.

Important: A rising line should only be used where the process steam pressure is guaranteed to be higher than the condensate backpressure at the trap outlet. If not, the process will waterlog unless a pumping trap or pump-trap combination is used to provide proper drainage against the backpressure.

3.  Common return lines should also slope down and be non-flooded (Figure 14.3.4). To avoid flash steam occurring in long return lines, hot condensate from trap discharge lines should drain into vented receivers (or flash vessels where appropriate), from where it can be pumped on to its final destination, via a flooded line at a lower temperature.

Condensate pumping is dealt with in more detail in Module 14.4.

The condensate pipe siz​ing chart

The condensate pipe sizing chart (Figure 14.3.5) can be used to size any type of condensate line, including:

  • Drain lines containing no flash steam.
  • Lines consisting of two-phase flow, such as trap discharge lines, which are selected according to the pressures either side of the trap.

The chart (Figure 14.3.5):

  • Works around acceptable flash steam velocities of 15 - 20 m/s, according to the pipe size and the proportion of flash steam formed.
  • Can be used with condensate temperatures lower than the steam saturation temperature, as will be the case when using thermostatic steam traps.
  • Is used to size trap discharge lines on full-load conditions. It is not necessary to consider any oversizing factors for start-up load or the removal of non-condensable gases.
  • May also be used to estimate sizes for pumped lines containing condensate below 100°C. This will be discussed in Module 14.4.
14.3.5 Condensate pipe sizing chart

Using the condensate pipe sizing chart (Also available in Appendix 14.3.2)

Establish the point where the steam and condensate pressures meet (lower part of the chart, Figure 14.3.5). From this point, move vertically up to the upper chart to meet the required condensate rate. If the discharge line is falling (non-flooded) and the selection is on or between lines, choose the lower line size. If the discharge line is rising, and therefore likely to be flooded, choose the upper line size.

Note: The reasoning employed for the sizing of a steam trap is different to that used for a discharge line, and it is perfectly normal for a trap discharge line to be sized different to the trap it is serving. However, when the trap is correctly sized, the usual ancillary equipment associated with a steam trap station, such as isolation valves, strainer, trap testing chamber, and check valve, can be the same size as the trapping device selected, whatever the discharge line size.

Example 14.3.3 1 On the chart (Figure 14.3.6)

A steam trap passing a full-load of 1000 kg/h at 6 bar g saturated steam pressure through a falling discharge line down to a flash vessel at 1.7 bar g.

As the discharge line is non-flooded, the lower figure of 25 mm is selected from the chart (Figure 14.3.5).

Figure 14.3.6 - Learn About Steam

Example 14.3.4 2 on the chart (Figure 14.3.7)

A steam trap passing a full-load of 1 000 kg/h at 18 bar g saturated steam pressure through a discharge line rising 5 m up to a pressurised condensate return line at 3.5 bar g.

Add the 0.5 bar static pressure (5 m head) to the 3.5 bar condensate pressure to give 4 bar g backpressure. 

As the discharge line is rising and thus flooded, the upper figure of 32 mm is selected from the chart, (Figure 14.3.5).

Fig 14.3.7 Learn About Steam

Example 14.3.5 3 on the chart (Figure 14.3.8)

A steam trap passing a full-load of 200 kg/h at 2 bar g saturated steam pressure through a sloping discharge line falling down to a vented condensate receiver at atmospheric pressure (0 bar g).

As the line is non-flooded, the lower figure of 20 mm is selected from the chart, (Figure 14.3.5).

Fig 14.3.8 Learn About Steam

Example 14.3.6 4 on the chart (Figure 14.3.9)

A pump-trap passing a full-load of 200 kg/h at 4 bar g saturated steam space pressure through a discharge line rising 5 m up to a non-flooded condensate return line at atmospheric pressure.

The 5 m static pressure contributes the total backpressure of 0.5 bar g.

As the trap discharge line is rising, the upper figure of 25 mm is selected from the chart, (Figure 14.3.5).

Fig 14.3.9 Learn About Steam

Example 14.3.7 5 on the chart (Figure 14.3.10)

Consider a condensate load of 200 kg/h to a receiver and pump. In this case, the condensate line is based on the maximum capacity of the pump to achieve the desired delivery head. Calculating pump capacities is covered in Module 14.4 ‘Pumping Condensate from Vented Receivers’, but for this example, it is assumed that the maximum condensate load will be 1 200 kg/h.

Because the condensate will have lost its flash steam content to atmosphere via the receiver vent, the pump will only be pumping liquid condensate. In this instance, it is only necessary to use the top part of the chart in Figure 14.3.5. As the line from the pump is rising, the upper figure of 25 mm is chosen.

Note: If the pumped line were longer than 100 m, the next larger size must be taken, which for this example would be 32 mm. A useful tip for lines of 100 m or less is to choose a discharge pipe which is the same size as the pump. For further details refer to Module 14.4 ‘Pumping condensate from vented receivers’.

 
Fig 14.3.10 Learn About Steam

Common return lines - falling lines

It is sometimes necessary to connect several trap discharge lines from separate processes into a common return line. Problems will not occur if the following considerations are met:

  • The common line is not flooded and slopes in the direction of flow to an open end or a vented receiver, or a flash vessel if the conditions allow.
  • The common line is sized on the cumulative sizes of the branch lines, and the branch lines are sized from Figure 14.3.5.

Example 14.3.8

Figure 14.3.11 shows three heat exchangers, each separately controlled and operating at the same time. The condensate loads shown are full loads and occur with 3 bar g in the steam space.

The common line slopes down to the flash vessel at 1.5 bar g, situated in the same plant room. Condensate in the flash vessel falls via a float trap down to a vented receiver, from where it is pumped directly to the boiler house.

The trap discharge lines are sized on full-load with steam pressure at 3 bar g and condensate pressure of 1.5 bar g, and as each is not flooded, the lower line sizes are picked from the graph.

Determine the condensate line sizes for the falling discharge lines and common lines.

Fig 14.3.11 Learn About Steam

Common return lines - rising lines

It is sometimes unavoidable for condensate discharge and common lines to rise at some point between the trap and the point of final termination. When this is the case, each discharge line is sized by moving up to the next size on the chart, as previously discussed in this Module.

Example 14.3.9

Figure 14.3.12 shows the same three heat exchangers as in Example 14.3.8.

However, in this instance, the common line rises 15 m and terminates in an overhead non-flooded condensate return main, giving the same backpressure of 1.5 bar as in Example 14.3.8. Each of the discharge lines is sized as a rising line.

Determine the condensate line sizes for the discharge lines and common lines.

Fig 14.3.12 Learn About Steam

Example 14.3.10 - Falling common line

Calculating the common line sizes for the application shown in Fig. 14.3.12 which falls to a final termination point:

Appendix 14.3.10

Example 14.3.11 - Rising common line

Calculating the common line sizes for the application shown in Fig. 14.3.14 which rises to a final termination point:

Note that the steam loads are the same as Example 14.3.10, but the discharge lines are one size larger due to the rising common line.

Appendix 14.3.14

The procedure shown in Examples 14.3.10 and 14.3.11 can be simplified by using Appendix 14.3.3.

For example, where pipes A and B (20 mm and 50 mm) join, the minimum required pipe diameter is shown as 54 mm. Clearly, the user would fit the next largest size of commercial pipe available, unless the calculated bore is close to a nominal bore size pipe.

Appendix 14.3.1 Flow of water in heavy steel pipes

Flowrate kg/h
Pipe size Ø 15
mm
20
mm
25
mm
32
mm
40
mm
50
mm
65
mm
80
mm
100
mm
Pa/m mbar/m <0.15 m/s 0.15 m/s 0.3 m/s
10 0.1 50 119 223 490 756 1 447 2 966 4 644 9 432
12.5 0.125 58 133 252 554 853 1 634 3 348 5 220 10 656
15 0.15 65 151 277 616 943 1 807 3 708 5 760 11 736
17.5 0.175 68 162 302 670 1 026 1 966 4 032 6 264 12 744
20 0.2 76 176 328 720 1 105 2 113 4 320 6 732 13 680
22.5 0.225 79 187 349 770 1 177 2 254 4 608 7 164 14 580 0.5 m/s
25 0.25 83 198 371 814 1 249 2 387 4 860 7 596 15 408
27.5 0.275 90 209 389 857 1 314 2 513 5 112 7 992 16 200
30 0.3 94 220 410 900 1 379 2 632 5 364 8 352 16 956
32.5 0.325 97 230 428 940 1 440 2 747 5 616 8 712 17 712
35 0.35 101 241 446 979 1 498 2 858 5 832 9 072 18 432
37.5 0.375 104 248 464 1 015 1 555 2 966 6 048 9 396 19 116
40 0.4 112 259 479 1 051 1 609 3 071 6 264 9 720 19 764
42.5 0.425 115 266 497 1 087 1 663 3 175 6 480 10 044 20 412
45 0.45 119 277 511 1 123 1 717 3 272 6 660 10 368 21 024
47.5 0.475 122 284 526 1 156 1 768 3 370 6 876 10 656 21 636
50 0.5 126 292 540 1 188 1 814 3 463 7 056 10 944 22 212
52.5 0.525 130 299 558 1 220 1 865 3 553 7 236 11 232 22 788
55 0.55 130 306 572 1 249 1 912 3 636 7 416 11 520 23 364
57.5 0.575 133 317 583 1 282 1 958 3 744 7 596 11 808 23 904
60 0.6 137 324 598 1 310 2 002 3 816 7 776 12 060 24 444
62.5 0.625 140 331 612 1 339 2 048 3 888 7 920 12 312 24 984
65 0.65 144 338 626 1 368 2 092 3 996 8 100 12 600 25 488
67.5 0.675 148 346 637 1 397 2 131 4 068 8 280 12 852 25 992
70 0.7 151 353 652 1 422 2 174 4 140 8 424 13 068 26 496
72.5 0.725 151 356 662 1 451 2 218 4 212 8 568 13 320 27 000
75 0.75 155 364 677 1 476 2 257 4 284 8 748 13 572 27 468
77.5 0.775 158 371 688 1 505 2 297 4 356 8 892 13 788 27 972
80 0.8 162 378 698 1 530 2 336 4 464 9 036 14 040 28 440 1 m/s
82.5 0.825 166 385 709 1 555 2 372 4 536 9 180 14 256 28 872
85 0.85 166 389 724 1 580 2 412 4 608 9 324 14 472 29 340
87.5 0.875 169 396 734 1 606 2 448 4 680 9 468 14 724 29 772
90 0.9 173 403 745 1 627 2 488 4 716 9 612 14 940 30 240
92.5 0.925 176 407 756 1 652 2 524 4 788 9 756 15 156 30 672
95 0.95 176 414 767 1 678 2 560 4 860 9 900 15 372 31 104
97.5 0.975 180 421 778 1 699 2 596 4 932 10 044 15 552 31 500
100 1 184 425 788 1 724 2 632 5 004 10 152 15 768 31 932
120 1.2 202 472 871 1 897 2 898 5 508 11 196 17 352 35 100
140 1.4 220 511 943 2 059 3 143 5 976 12 132 18 792 38 160
160 1.6 234 547 1 015 2 210 3 373 6 408 12 996 20 160 40 680
180 1.8 252 583 1 080 2 354 3 589 6 804 13 824 21 420 43 200 1.5 m/s
200 2 266 619 1 141 2 488 3 780 7 200 14 580 22 644 45 720
220 2.2 281 652 1 202 2 617 3 996 7 560 15 336 23 760 47 880
240 2.4 288 680 1 256 2 740 4 176 7 920 16 056 24 876 50 400
260 2.6 306 713 1 310 2 855 4 356 8 244 16 740 25 920 52 200
280 2.8 317 742 1 364 2 970 4 536 8 568 17 388 26 928 54 360
300 3 331 767 1 415 3 078 4 680 8 892 18 000 27 900 56 160

Appendix 14.3.2 Condensate pipe sizing chart

Appendix 14.3.3 Common pipe sizing table

D1 = Connecting branch size (N.B.) D2 = Common pipe size

D2 D1 - Connecting branch size (NB)
15 20 25 32 40 50 65 80 100
15 21 25 29 35 43 52 67 81 101
16 22 26 30 36 43 52 67 82 101
17 23 26 30 36 43 53 67 82 101
18 23 27 31 37 44 53 67 82 102
19 24 28 31 37 44 53 68 82 102
20 25 28 32 38 45 54 68 82 102
21 26 29 33 38 45 54 68 83 102
22 27 30 33 39 46 55 69 83 102
23 27 30 34 39 46 55 69 83 103
24 28 31 35 40 47 55 69 84 103
25 29 32 35 41 47 56 70 84 103
26 30 33 36 41 48 56 70 84 103
27 31 34 37 42 48 57 70 84 104
28 32 34 38 43 49 57 71 85 104
29 33 35 38 43 49 58 71 85 104
30 34 36 39 44 50 58 72 85 104
31 34 37 40 45 51 59 72 86 105
32 35 38 41 45 51 59 72 86 105
33 36 39 41 46 52 60 73 87 105
34 37 39 42 47 52 60 73 87 106
35 38 40 43 47 53 61 74 87 106
36 39 41 44 48 54 62 74 88 106
37 40 42 45 49 54 62 75 88 107
38 41 43 45 50 55 63 75 89 107
39 42 44 46 50 56 63 76 89 107
40 43 45 47 51 57 64 76 89 108
41 44 46 48 52 57 65 77 90 108
42 45 47 49 53 58 65 77 90 108
43 46 47 50 54 59 66 78 91 109
44 46 48 51 54 59 67 78 91 109
45 47 49 51 55 60 67 79 92 110
46 48 50 52 56 61 68 80 92 110
47 49 51 53 57 62 69 80 93 110
48 50 52 54 58 62 69 81 93 111
49 51 53 55 59 63 70 81 94 111
50 52 54 56 59 64 71 82 94 112
51 53 55 57 60 65 71 83 95 112
52 54 56 58 61 66 72 83 95 113
53 55 57 59 62 66 73 84 96 113
54 56 58 60 63 67 74 85 97 114
55 57 59 60 64 68 74 85 97 114
56 58 59 61 64 69 75 86 98 115
57 59 60 62 65 70 76 86 98 115

 

D2 D1 - Connecting branch size (NB)
15 20 25 32 40 50 65 80 100
58 60 61 63 66 70 77 87 99 116
59 61 62 64 67 71 77 88 99 116
60 62 63 65 68 72 78 88 100 117
61 63 64 66 69 73 79 89 101 117
62 64 65 67 70 74 80 90 101 118
63 65 66 68 71 75 80 91 102 118
64 66 67 69 72 75 81 91 102 119
65 67 68 70 72 76 82 92 103 119
66 68 69 71 73 77 83 93 104 120
67 69 70 72 74 78 84 93 104 120
68 70 71 72 75 79 84 94 105 121
69 71 72 73 76 80 85 95 106 121
70 72 73 74 77 81 86 96 106 122
71 73 74 75 78 81 87 96 107 123
72 74 75 76 79 82 88 97 108 123
73 75 76 77 80 83 88 98 108 124
74 76 77 78 81 84 89 98 109 124
75 76 78 79 82 85 90 99 110 125
76 77 79 80 82 86 91 100 110 126
77 78 80 81 83 87 92 101 111 126
78 79 81 82 84 88 93 102 112 127
79 80 81 83 85 89 93 102 112 127
80 81 82 84 86 89 94 103 113 128
81 82 83 85 87 90 95 104 114 129
82 83 84 86 88 91 96 105 115 129
83 84 85 87 89 92 97 105 115 130
84 85 86 88 90 93 98 106 116 131
85 86 87 89 91 94 99 107 117 131
86 87 88 90 92 95 99 108 117 132
87 88 89 91 93 96 100 109 118 133
88 89 90 91 94 97 101 109 119 133
89 90 91 92 95 98 102 110 120 134
90 91 92 93 96 98 103 111 120 135
91 92 93 94 96 99 104 112 121 135
92 93 94 95 97 100 105 113 122 136
93 94 95 96 98 101 106 113 123 137
94 95 96 97 99 102 106 114 123 137
95 96 97 98 100 103 107 115 124 138
96 97 98 99 101 104 108 116 125 139
97 98 99 100 102 105 109 117 126 139
98 99 100 101 103 106 110 118 127 140
99 100 101 102 104 107 111 118 127 141
100 101 102 103 105 108 112 119 128 141