Introduction
Choosing what type of pipe is needed for a given application is part of industrial engineering and project design. However, not all industrial pipes are manufactured the same way. In fact, the manufacturing process of a given pipe can affect its characteristics, dimensional stability and suitability for a certain application. The two primary pipe manufacturing methods are seamless and welded. The choice of seamless or welded is determined by a number of criteria, including pressure, temperature, material, size, application, availability and specification. Understanding the difference between seamless pipe and welded pipe is important to engineers or purchasing engineers who wish to make informed decisions. This article examines the difference between seamless steel pipe and welded steel pipe and where each type of pipe may find application.
What Is a Seamless Pipe?
A seamless pipe is manufactured without a longitudinal weld seam. The initial material for seamless pipe manufacturing is a solid round billet. The billet is heated and pierced to produce a hollow tube. The tube can be subjected to further processes such as rolling, cold drawing, heat treatment, straightening and finishing depending on the desired result.
The welding seam in a seamless pipe is absent, and this is what determines the pipe’s ability to carry pressure, dimensional stability and other characteristics. Seamless pipes are supplied in various carbon and alloy grades, sizes, thickness and standards depending on the intended application.
What Is a Welded Pipe?
A welded pipe is produced from a flat steel plate, strip or coil which is formed into a cylindrical shape.
The formed sheet is then joined together with a weld. Depending on the method of manufacturing, welded pipes can be produced in a variety of diameters and sizes with varying welds and finish.
The welding process is an important aspect of welded pipe production. Sufficient testing and manufacturing processes are required to ensure that the final welded pipe product can carry the specified load.
Seamless Pipe vs Welded Pipe: Key Differences
The main difference between seamless and welded pipes is the manufacturing method since one type of pipe is produced without a weld and the other is produced with a weld. The seamless pipe is formed from a solid round billet while the welded pipe is formed from a flat strip, plate or coil. This determines the application for which each pipe is suitable.
1. Manufacturing Method
Seamless pipes are produced from a solid round billet. The processes involved include piercing, rolling, drawing, heat treatment, straightening and finishing. Welded pipes are produced from steel strip, plate or coil. The manufacturing process involves forming the strip or plate into a cylindrical shape and joining the edges with welds. The production route has to be considered when determining the suitability of a welded pipe for a certain application.
2. Pressure Considerations
For applications which require pipes to withstand high pressure, seamless pipes are often used due to the absence of a longitudinal weld seam. However, the choice of pipe is influenced by a number of other considerations including the grade of material, wall thickness, temperature, size, standard and testing requirements.
3. Dimension and Availability
Welded pipes can be produced in a range of diameters. Therefore, this type of pipe is preferred when large-dimensioned pipes are required. The manufacturing method allows the producer to offer a wide range of sizes and specifications. Seamless pipes are produced in a variety of diameters, but the combination of diameter and wall thickness is dependent on the manufacturing method and applicable standard for the intended application.
4. Application Requirements
The choice of seamless pipe or welded pipe depends on the intended application for the pipe. Seamless pipes are used in such industries as boiler, heat exchangers, petrochemical, hydraulic applications and other demanding applications where the pressure, temperature and other characteristics of the medium are of concern. Welded pipes on the other hand find application in industrial, structural, water, construction and process applications where the characteristics and specifications of the welded pipes are suitable.
Which One Is Better for Industrial Applications?
It is not possible to determine which one is better for industrial applications since seamless and welded pipes are manufactured to different specifications to suit different applications. For a high-pressure application or otherwise demanding application, engineers may specify seamless steel pipe for its unique characteristics. For other applications where diameter size, economics or other considerations are a concern, welded steel pipes are suitable. The choice of seamless or welded pipes should therefore be determined by the intended application and operating conditions rather than comparing the two products directly.
Important factors include:
- Operating pressure
- Operating temperature
- Material grade
- Outside diameter
- Wall thickness
- Required length
- Corrosion conditions
- Applicable standard
- Testing and inspection requirements
- Installation requirements
Why Specification Matters
A pipe should always be chosen based on a specification. A specification defines the material grade, dimensions and tolerances, mechanical properties, test requirements, and other information necessary for the final pipe product.
For the industrial buyer, the choice of seamless steel pipe or welded steel pipe is important since two seemingly similar pipes may not be interchangeable due to differences in grade, standard, or any other requirement.
At Sainest Tubes, seamless tubes and pipes are manufactured for applications which demand dimensional stability, material characteristics, inspection and other considerations.
Conclusion
When examining seamless pipe vs welded pipe, it is important to note that neither option is better than the other. The choice of seamless or welded pipes should be determined by the operating and technical requirements of the intended application. Seamless pipe provides a continuous surface without a longitudinal weld seam and is therefore better suited for demanding applications. Welded pipe on the other hand is better suited for applications which require a wider range of sizes, and where other considerations are of concern. At Sainest Tubes, the company focuses on understanding the requirements of the application and manufacturing seamless tubes and pipes to the specifications demanded by the requirements.
