Steel pipes 2 Essay Example

Executive Summary

Steel pipes have a wide range of applications in different industries and are a natural option for corrosion and heat resistant metal applications. They have extraordinary properties including low permeation to gases like hydrogen, methane and natural gas, excellent crack resistance caused by stresses, superior impact resistance and can lie underground for several years. Corrosion is the primary cause for degradation in the performance of steel pipes, leading to loss of quality and high cost of operation. There are a number of methods that are used to prevent pipe corrosion. In this work, we focus on friction stir welding (FSW) as a solution for corrosion, which is the main problem that affects the durability and performance of pipelines. To maintain the performance and life service of steel pipes, they must be protected from corrosion. From our studies, we concluded that FSW is one of the best welding methods that can be used to protect steel pipes from corrosion.

Student Reflection

We learnt that steel pipes have a variety of applications in many projects. There are two types of steel pipes: welded steel pipes (seamed pipes) and seamless pipes. The major challenge facing steel pipes is corrosion. This can be prevented by applying methods such as protection coat, anodic and cathodic protection, galvanization of the steel pipe, and using FSW instead of using Electric Resistance Welding (ERW). By working together in the project, we found that FSW provides the best welding method for the protection of steel pipes over a long period of time. We also recognized the importance of developing teamwork when working on a project as it involves different individuals with different expertise, whose input must be coordinated in order to achieve the desired results.

Table of Content

iExecutive Summary

iStudent Reflection

1Introduction

1Background literature on the topic

2Critical and unresolved issues and proposed research directions

3Proposed solution

5Conclusions

6References

Introduction

Steel pipes can be defined as long, hollow tubes that have a wide range of applications. They are produced using two distinct methods to obtain two types which are welded Pipe (seamed pipes) and seamless Pipe. Both types have different uses. Welded pipes are heavier and rigid and typically straight with a better consistency. They are used in places where the pipe is not subjected to a high degree of stress. Seamed pipes’ applications include gas transportation, plumbing and electrical conduits. Since Seamless pipes are lighter and have thin walls, they are used for liquids transporting and bicycle frames (Advameg, Inc., 2017).

Steel pipes are made of high grade steel, materials with properties of high corrosion resistance combined with excellent physical and mechanical properties. Methods that are currently used in the fabrication of steel pipes include: centrifugal casting, sub-merged arc welding, roll piercing, electric resistance welding and friction stir welding.

In this report, we cover the history of steel pipes, types and how they are manufactured. The report also covers the issue of pipe corrosion, which is the major problem in the manufacture of steel pipes. Methods used to prevent corrosion have also been discussed, with our focus on friction stir welding as an alternative welding method to electric resistance welding which creates conditions that favor pipe corrosion.

Background literature on the topic

Pipes have been used by human beings for thousands of years. As early as 2000 BC, ancient civilizations were using reed pipes, clay tubes, bamboo tubes, and wood logs to transport water. The first lead pipe was constructed during the first century in Europe. The use of modern steel pipes can be traced back to early 1800s.The earliest method of constructing pipes was patented in 1824 by James Russell. Using this method, metal tubes were made by welding together opposite edges of an iron strip and passing it through a rolling mill. An improved method called the butt-weld process was later invented by Comelius Whitehouse in the following year. This method forms the basis of the modern pipe making procedures. Improvements in the Whitehouse method were innovated in 1911 by John Moon who created a continuous process method to manufacture pipes in an unending stream. The first plant to manufacture seamless tubes was built in 1895. Seamless tubes were made by drilling a hole through a solid metal. Current methods use new roller techniques to manufacture seamless pipes (Advameg, Inc., 2017).
Because of the low efficiency of cold-riveted and welded edges and the low tensile strengths in early steel, engineers set the a safe design stress of 68.95 MPa (10,000 psi). As pipe fabrication methods continued to improve, higher strengths steels were manufactured, and the design stresses moved from 68.95 MPa to 86.18 MPa, to 94.8 MPa, and finally to 103.42 MPa (15,000 psi). It was necessary to adjust the design stresses in order to account for the riveted seam efficiency. Based on the tensile strength, engineers recommended a safety factor of 4-to-1 for steel pipes (American Water Works Association, 2004).

Critical and unresolved issues and proposed research directions

Root Causes of corrosion

There are a number of factors that cause corrosion in steel pipes. These factors are usually interrelated and include fluid (medium) characteristics (velocity, pH, temperature, amount of oxygen available, chemical characteristics etc.), the design of the pipe line (these include joining methods, methods of protection, use of dissimilar metals in contact with the pipe system etc.), the material used to manufacture the pipes, and the time
(Edwards, Scardina, & McNeill, 2005). The figure below provides a summary of factors that lead to pipe corrosion.

steel pipes 2

Figure 1: Factors that lead to pipe corrosion

Proposed solution

The proposed solution to address the problem of corrosion in pipes is the use of friction stir welding method instead of electric resistance welding method. Friction stir welding is solid-state joining process that utilizes a non-consumable tool to join two workpieces without melting the material. FSW has exhibited many advantages in the pipeline industry over the traditional arc welding process. The method reduces distortion of the material and produces a high quality weld with low heat input In addition, FSW is relatively cheaper than traditional welding methods, and is more environmentally friendly.

FSW involves joining two plates without using filler materials or fusion. The welding tool is made of a circular section except near the end where it is made into a threaded probe. The junction of the probe and the cylindrical section is known as the “shoulder”. During the joining process, the probe penetrates the material while the shoulder rubs the material with the top surface. The deformation near the pin contributes to the heat generated from the adiabatic heating. The friction between a rotating tool and the shoulder generates friction which produces heat. The welding parameters are modified to ensure that there is sufficient heat input per unit length of the material. The heat generated cause the stirred material to start softening without melting. As the rotating tool moves forward, the two plates are forced together by shear plastic stresses under the high temperature. Figure two below illustrates how the FSW process works (Defalco & Steel, 2009).

steel pipes 2 1

Figure 2: Illustration of how FSW works

Advantages of High-Melting-Temperature FSW:

  • No defects, cracking and porosities

  • Less grooving

  • Better weld joint

  • No molten spray

  • No gas shielding

  • No filler material or flux needed

  • FSW can be fully automated

  • Efficient energy input

  • Require minimum inspection after welding due to solid-state joining and process repeatability.

  • No formation of weld spatter.

  • The process is tolerant to interface gaps and requires little or no pre-weld preparations.

  • Leaves a smooth surface with little or no flash.

  • No harmful emissions generated

  • Materials can be joined using a single pass

Advantages of friction stir welding over traditional welding methods in steel pipes: Compared to traditional fusion welding methods such as laser beam and arc welding, FSW has the following advantages:

  • High energy efficiency

  • Offers high quality weld

  • The welded joint has desirable mechanical properties such as high strength, high toughness, and high fatigue resistance.

  • FSW method is highly productive.

  • Can be used to join dissimilar metals and composites.

  • Environmentally friendly

  • There are fewer welding parameters to monitor

How to implement FSW in a pipe production line

FSW has been used in on-site pipe welding by developing a portable rotating machine. The portable pipe welding machine has been designed with the capability of friction stir welding stationery pipes like those ones in the pipeline assembly. It has been designed to produce a single pass, complete joint penetration welds on an ID pipe (Defalco & Steel, 2009).

Technology Development

FSW is constantly developing and becoming more advanced. Currently, the FSW process limits the thickness of the pipe, but single pass welding of steel (API grade) with thickness of 1 in. is being developed. Welding tubular geometries require more complex and sophisticated tool designs than linear welding. Pipeline development has shifted to use of high strength steel grades which provide cost savings, but also have difficulties when using traditional welding methods. There is need to have a careful development of parameters used in FSW in order to work with the special grades of steel (Defalco & Steel, 2009).

Conclusions

Since steel pipelines were first introduced in the early 1980s, the methods used to fabricate steel pipes have greatly evolved, with a wide range of application in many areas. For efficient performance of steel pipes, and longer design service life, there is need to prevent the problem of corrosion, which is the biggest challenge in pipelines. Electric resistance welding has been in use for many years as a cheap and effective way of fabricating pipes. However, it does not offer high quality weld and favors corrosion in pipe systems. FSW promises an alternative pipe welding method that is cheaper and more sustainable, with the capability to minimize pipe corrosion. There is need to carry out further research on how to develop FSW tool designs that does not limit the pipe thickness.

Each member of our team contributed significantly to the study, which helped in building a sense of teamwork to achieve the required results. We would recommend that pipe manufacturers to implement FSW in the pipe manufacturing line as a way of minimizing corrosion in pipes.

References

Advameg, Inc. (2017). Steel Pipe. Retrieved May 23, 2017, from www.madehow.com › Volume 5

American Water Works Association. (2004). History, Uses, and Physical Characteristics of Steel Pipe. U.S.A: American Water Works Association.

Defalco, J., & Steel, R. (2009). Friction Stir Process Now Welds Steel Pipe.

Edwards, M., Scardina, P., & McNeill, L. (2005). Enhanced Coagulation Impacts on Water Treatment Plant Infrastructure. IWA Publishing.