ERW / HFI tube fabrication is the fastest methods to produce tube product and the industry is one of the most competitive environments where high volume does not necessarily equate to profit.

Material is trending towards higher tensile strengths and thinner gauges pressing the importance of presenting the forming tube to the weld box properly.

Courtesy of EFD Induction

¹Decreased yield percentages or high scrap rates involve four main factors:

• Mill setup
• Poor forming
• Weld faults
• Customer quality non compliance

How Manufacturers can improve their process yield

The process of welding tube and pipe requires several variables to be in check for efficient stable production. The material type, gauge, edge condition, tooling setup, and weld heat are just a few of the factors that quality control managers, mill supervisors, and operators must pay attention to in their efforts to achieve output and efficiency targets. In addition to controlling variables to maximize yield and optimize efficiency, they also must meet the quality demands of the market. Mill dynamics, from setup to production, ultimately impact profitability, competitiveness and the reputation of industry players. Optical tube measurement during setup and production offers gains in efficiency and yield with a goal to reduce scrap and waste by 25%

This paper will present the challenges facing tube fabricators which impede mill efficiency and profitability and introduce the advantages of optically measuring the in-feed tube forming parameters for setup and production as an early indicator for potential mill and material problems.

Market Trends

In an industry where the supply & demand curve can swing a firm from profit to loss within a fiscal year, tube fabricators face continual pressure from supplier side steel prices, competitor side capacity and buyer side quality demands. The environmental pressure from national and offshore competition, energy availability and conservation impact the profit dynamic as well.

By its nature, the tube industry was inefficient and continues to be so. The market forces that shape the industry, have also forced the survivors to redefine it. The industry has undergone mill maneuvers as firms with heavy coffers acquired or consolidated with complimentary or competing fabricators. Companies have also closed plants to relocate their assets to lower cost based countries. With the jostling taking place, experienced mill operators may have been lost in the shuffle thereby shrinking the experience pool. In mature markets the remaining players are in expansion. In the emerging markets, new fabricators are coming online annually which is increasing the regions prominence for tube fabrication on the world stage.

The Challenges Facing Tube Fabricators

Tube mill operators, mill supervisors and quality managers face a variety of daily challenges that impede their efforts to produce high quality tube product. As the old adage goes “garbage in, garbage out” and the same thing applies to tube fabricators.

A common condition which impacts the sizing and wall thickness after scrafing is the strip edges entering the welding area in non parallel fashion. This produces a step, mismatch, which then causes irregular sizing downstream through the sizing area. While it is difficult to root out the main cause, the two most probable causes are improper setup in the breakdown, forming and fin section to ensure proper presentation to the welding section and strip rolling in the breakdown section which may cause the strip to ride high on one side. The strip edge riding high on one side can also be caused by negative tension in the tube mill. The back pressure causes the material to buckle and since the energy needs to be released the material follows the path of least resistance, up the side of a forming roller.

It is worthwhile to note that there can be two kinds of edge misalignment which leads to defects. The first one mentioned in the previous paragraph is a trending error and the second one is an intermittent error which is a wrinkle in the strip material over a short distance. This second disturbance can be the result of misaligned breakdown passes, improper edge preparation or possibly a raw material supplier quality issue.

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