TPT September 2020

AR T I C L E

Xiris Automation

Justifying the cost of investing in automatic weld inspection on a tube mill By Xiris Automation

The table numbers form the basis of justifying new equipment purchases by measuring the effect, before and after the purchase, on the resources required to make tube. With capacity targets in mind, let’s look at where savings can be made to get as close to capacity as possible. Calculating the tangible savings A number of tangible savings can be measured – and achieved – by implementing an automatic weld inspection system on a tube mill. Let us have a look at the most significant sources of tangible savings: 1) Reduced set-up time Every time a tube mill is changed over to run a new product, a set-up process must be performed to adjust the mill accordingly. This process can be quite time consuming as a number of variables, input materials and equipment need to be adjusted to allow the mill to run the best quality product possible. Reducing the set-up process time and complexity is welcome news to all mill operators. By adding an automatic weld inspection system on a tube mill, immediate feedback of the weld geometry of the tube being produced can be provided to the mill operators as set-up adjustments are being made. The result is a faster set-up process, less mill downtime and a more efficient tube mill overall. 2) Reduced lab time Lab time is a precious commodity. As part of the changeover process on a tube mill, the tube produced has to be qualified to a desired level of quality in the lab prior to production. This line qualification process often includes cutting as many as three separate cross sections of a tube and sending them to the lab for processing where they get polished and photographed as micrographs. Once created, the micrographs can be measured or analysed to verify that the weld structure of the tube meets the specifications required by the customer. Two of the most important competitive advantages in making a tube are the quality of the weld and the forming profile of the tube. So how can you improve your quality while driving down costs and delivery times? You need productivity investments that provide a suitable justification, often relying on the Return on Investment (ROI) calculation of the purchase with cold, hard figures. Sounds like an easy decision to make?

Long-term thinking ROI calculations are fairly easy to do and understand, but should be considered over the long term. Most tube and pipe fabricators typically base ROI calculations on short-term benefits such as direct labour savings and reduced material inputs. But investing in equipment, such as an automatic weld inspection system for a tube mill, has both immediate and long-term benefits, creating ongoing savings for years to come. And those savings are both tangible (measurable) and intangible (not directly measurable). Star t with some assumptions In order to justify the purchase of an automatic weld inspection system based on its ROI, we need to make a number of assumptions about line data from the tube mill on which it will be placed. While each production line is different, the following data profile is typical of the capacity of an average small diameter stainless steel mill: Faster delivery, better quality and lower prices. Customers want it all and they want it immediately. At the same time, competition is growing all of the time. From across the street to across the world, competitors are everywhere in the tube business. For most tube producers, it is getting more and more difficult to generate sustained profitability.

Number of production days per year Number of production hours per day Average production line speed Total linear tube/pipe produced per year Average diameter of tube/pipe

230

days/year

16

hours/day

12

m/min

2,649,600

m/year

60

mm

Average wall thickness of tube/pipe

3

mm

Density of material

7,800

kg/m 3

Unit cost of input material Total value of material consumed per year

0.38

$/kg

$ 4,438,750

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SEPTEMBER 2020