Have you ever wondered how to determine the amount of Thermic Lance required to cut a certain object or to complete your project? To answer this question, we need to know the cutting ability of the Thermic Lance type and size you intend to use for the work.
In this blog, we will show you how to calculate the quantity of thermic lance needed for your work based on the performance test result.
Thermic Lance is a power cutting tool made of a steel pipe filled with steel wire rods as a core inside it using only pressurized oxygen to make combustion and generate high temperature up to 4000 degree Celsius to break up large metal objects quickly and efficiently. There are other names that refer to thermic lance out there like thermal lance, burning lance, burning bar, but all are the same thing and all use the principle of exothermic reaction to produce heat.
Daiwa Lance International Company is a leading Thermic Lance producer in the world with a factory located in Vietnam. There are two types of designs for Daiwa Thermic Lance to use for different applications and different metal materials to be cut.
This product is suitable for boring and cutting metal materials that require high heat and stronger oxygen flow to break up such as carbon steel, cast iron, aluminium, etc.
In order to verify the cutting ability of Daiwa Thermic Lance, we conducted a cutting test on a carbon steel slab. The cutting object is a SS400 grade steel slab with a thickness of 80mm and length of 1,000mm.
The test was conducted with 4 samples of thermic lance of different sizes and different designs to cut the same length of 500mm to find the most suitable size and type of thermic lance for cutting application based on parameters of lance consumption and cutting time.
The summary of performance results are shown in a table below
TEST RESULT DATA|
Thermic Lance size and Type |
TYPE T (3/8") |
TYPE W (3/8") |
TYPE T (1/4") |
TYPE T (1/2") |
| Pipe size (mm) |
17.3 |
17.3 | 13.8 | 21.7 |
| Base Steel grade | SS400 | SS400 | SS400 | SS400 |
| Oxy pressure (Bar) | 11 | 11 | 11 | 11 |
| Oxy flow rate(m3/h) | 25 | 16 | 12 | 33 |
| Pipe length consumption(mm) | 1306 | 2119 | 1892 | 1573 |
| CuttingTime(Sec) | 103 | 174 | 162 | 154 |
| Cutting line (mm) | 80 x 20 | 80 x 20 | 80 x 15 | 80 x 25 |
| Cutting Length (mm) | 500 | 500 | 500 | 500 |
Based on the test result data above, we can calculate and convert the performance of each thermic lance in case a full length of 3 meters was consumed.
The converted cutting performance is shown in the following table.
CALCULATED PERFORMANCE for 1PC of THERMIC LANCE
| Size of thermic lance | 3/8" x 3.0M Type-T | 3/8" x 3.0M Type-W | 1/4" x 3.0M Type-T | 1/2" x 3.0M Type-T |
| Length of lance pipe (mm) | 3,000 | 3,000 | 3,000 | 3,000 |
| Grade of cut base metal | Steel Slab SS400 | Steel Slab SS400 | Steel Slab SS400 | Steel Slab SS400 |
| Width of cutting line (mm) | 20 | 20 | 15 | 25 |
| Thickness of base metal (mm) | 80 | 80 | 80 | 80 |
| Cutting Time (Sec) | 237 | 246 | 257 | 294 |
| Oxy consumption (m3) | 1.64 | 1.09 | 0.86 | 2.69 |
| Length of Cutting line (mm) | 1149 | 708 | 793 | 954 |
| Cutting area (m2) | 0.0919 | 0.0566 | 0.0634 | 0.0763 |
We can see from the calculated performance table that one piece of Daiwa Thermic Lance 3/8” x 3.0M Type-T would cut a line of 1,149mm long in 80mm deep and 20mm wide, equal to an area of 0.0919 m2 in 237 seconds with oxygen consumption of 1.64m3.
Similarly, one piece of Daiwa Thermic Lance 3/8” x 3.0M Type-W would cut an area of 0.0566 m2 in 246 seconds with oxygen consumption of 1.09m3; one piece of Daiwa thermic lance 1/4” x 3.0M Type-T would cut an area of 0.0634 m2 in 257 seconds with oxygen consumption of 0.86m3; one piece of Daiwa Thermic Lance 1/2” x 3.0M Type-T would cut an area of 0.0763 m2 in 154 seconds with oxygen consumption of 2.69m3
It is concluded that Thermic Lance size ⅜” Type-T is the most suitable product for cutting carbon steel. The test result shows that one piece of Daiwa Thermic Lance ⅜” x 3.0M Type-T can cut the length of 1149mm on the thickness of 80mm in just 237 seconds or roughly 4 minutes.
We also find out that the bigger the size of Thermic Lance, the lesser the cutting required for cutting in the same setting oxygen pressure. It means thermic lance size ½” will be burned faster than size ¼”. And thermic lance Type-T is performed better than Type-W in cutting carbon steel material.
As Thermic Lance is a powerful cutting tool, we can use Thermic Lance for the demolition of complex structures like offshore oil rigs. The structure of an oil rig platform was made of steel so it can be cut down by using Thermic Lance after the oil well is decommissioned to recycle the steel structure.
The demolition work is required to cut the top of the oil rigs for recycling of steel and use the remaining part of the leg to build a new offshore wind power plant or to build deep sea resorts for diving and fishing.
The old oil rig in this example has 5 stations, each station has 4 legs of steel pipe with the diameter of 1,498mm and thickness of 44.5mm.
The measurements of each leg are shown in the table below.
| PARAMETER (S) | STA | STB | STC | STD | MTA | |
| 1 | Leg Dia (At Bottom) | 59" x 1.5" (1498.8 x 38.1 mm) | 59" x 1.5" (1498.6 x 38.1 mm) | 59" x 1.5" (1498.6 x 38.1 mm) | 62" x 2" (1574 x 50 mm) | 60.5" x 1.75" (1536 x 44 mm) |
| 2 | Plle Dla (OD) | 54" (1371.6 mm) | 54" (1371.6 mm) | 54" (1371.6 mm) | 54" (1371.6 mm) | 54" (1371.6 mm) |
| 3 | Thickness | 44.45 mm | 44.45 mm | 44.45 mm | 44.45 mm | 50 mm |
Based on the performance data, we can make a calculation to estimate the quantity of Thermic Lance needed for cutting an offshore oil rig in a demolition work.
Our estimation is as follows:
However, as the work is taking place offshore in an expecting more difficult conditions than what we experimented with the test. Considering the logistics difficulty for an offshore works and for the sake of safe operations, we suggest the quantity of Thermic Lance needed is 214 pcs, double what actually calculated above, and oxygen needed is 642 m3 or 54 oxygen cylinders.
CALCULATION METHOD: To find out the Square Area we need to cut out (S cut = Square area need to cut)
S = r2 x Pi
| STA | STB | STC | STD | MTA | Total S cut 3.798 m2 |
||
| S cut = | 0.742 | 0.742 | 0.742 | 0.742 | |||
| Below is the actual performance testing at Daiwa Lance | |||||||
| S cut | Result of actual Vertical cut by 1pc: S=0.08 x 0.445 x1 | 0.0356 | m3 | ||||
| Lance (1pc) | 1 | pc | |||||
| Oxygen consump | 3 | m3 | |||||
| Base on above actual cut result in the stable condition in floor | |||||||
| 1) Thermic Lance need to cut all S=3.798 m2 , we need: | 107 | pcs | |||||
| 2) Oxygen consump: | 321 | m3 | |||||
| Sugesstion: | ||||||
| Consider the loss by uncertain condition in the offshore, loss maybe 2 times: | ||||||
| 1) Thermic Lance needed including loss ~ | 214 | pcs | ||||
| 2) Oxygen consump including loss: | ~ | 642 | m3 | |||
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Thermic Lance is a powerful cutting tool and it is advisable that Daiwa Thermic Lance can be used for demolition work either it is an oil rig or it is an abandoned mining structure. When we know the performance of each size and each type of thermic lance, we can certainly choose the right thermic lance to help your work safely and efficiently.
Our technical team at Daiwa Lance International Company can assist you when you need to estimate the quantity of thermic lance and oxygen volume required for your demolition projects.