Any tube/pipe without a seam or a weld joint is referred to as a seamless pipe. It is a tube made of solid, homogenous metal. Without using any welding joints, one tube is joined to each end of another. As a result, the resistance to high pressure, corrosive atmospheres, mechanical stress, and extremely high temperatures is increased. At times, both ends of a seamless tube contain a structure like a thread. This is used to join the end of one hollow tube to another. 

Seamless tubes are believed to withstand tremendous pressure from various industrial pressures. A seam or joint functions as a weak point for the tube, making this impossible with a welded tube. A seamless hydraulic tube is specifically designed to resist dynamic loads and high static, offering an enduring, staunch solution.  

Hydraulic seamless pipes  are widely used in petrochemical, refineries, power, chemical, aerospace, and automotive industries. Heat exchanger tubes, hydraulic tubes, boiler tubes, mechanical tubes, finned tubes, etc., required in these industries are seamless hydraulic tubes.  

Essential Features of Hydraulic Seamless Tubes  

  • Smooth interior and exterior surfaces
  • No seams or welds 
  • Thick scale-free surface 
  • High-pressure resistance 
  • Superior performance 
  • High corrosion resistance
  • Elevated durability 
  • Robustness 
  • High tensile strength 
  • High-reliability factor 

How Are Seamless Tubes/Pipes Made? 

Stainless steel, carbon steel, tungsten, and other solid round steel bars are frequently used to make seamless hydraulic pipes. First, the heated metal pieces are rolled over to the necessary forms, where they are transformed into hollow tubes. 

The Drawn Mandrel Method, known as the Cold Drawn Process, makes seamless tubes. This process ensures dimensional tolerance of the tube and a smooth finish for both interior and exterior sections. 

This procedure uses a furnace to heat the steel bar to an extremely high temperature. A cylindrical vacuum then develops. The requirement determines the tube's thickness. Additionally, several roll straightening machines run on these frameworks, taking care of the tubes' straightness. Finally, before the tubes leave the production facilities, they are put through several quality inspections. 

Here are four things that you may not know about hydraulic seamless, stainless-steel tubing/pipe: 

  1. How seamless pipes are manufactured

One of the ways seamless pipes are created is through extrusion. This is a process through which materials or metals are forced through a die to create desired shapes. The process starts with a conditioned steel piece of selected grade. Next, the tubes are extruded from a billet; then, it is redrawn using a die. The seamless pipe is heat-treated in a vacuum furnace, and then it is worked, cleaned and reworked until it gets back and reduced to the perfect and ideal size. The coil piping can be minimized so far down the inner diameter that it can be the same size as a human hair strand. 

  1. The difference between welded, welded-and-drawn, and hydraulic seamless pipe

Choosing  Hydraulic seamless pipesor tubing, welded, welded-and-drawn tubing, is quite a complex procedure. Tubing has better corrosion resistance as it is 100% seam-free without any orbital or longitudinal welds. However, the longitudinal welds can be present for a defect, and that cannot be tolerated in challenging applications. To manufacture a welded pipe, a flat strip is roll formed and connected with a longitudinal seam. This process can be accomplished by laser alignment or tig welding. The weld area is inconsistent dimensionally with the strip, and it causes areas of concentration, especially for pipes that are subjected to tremendous internal pressure. Moreover, the crevices exist on both sides of the weld seam. It creates opportunities for metallurgical contamination and corrosion in the heat treatment and can lead to corrosion as it traps residues. 

The crevices can cause cracks that can spread and rupture the welded pipes. Some pipe manufacturers use different methods for minimizing the dimensional variation and club the weld seam, including sink, roll, float or plug drawn. The products are identified by several names, such as welded-and-drawn, seam-free and seam-integrated. To homogenize the weld, redrawing as-welded tubing with a plug and die and following annealing helps a lot. However, to homogenize the weld, the operations must be repeated several times, increasing the total cost, whereas the seamless tubing has zero welds.  

  1. Popular applications for coiled tubing/pipe 

Seamless stainless steel coil tubing minimizes the threats of impurities and minimizes corrosion resistance and installation costs in multiple applications; therefore, it is a preferable choice for extreme environments. In the gas and oil industry, seamless pipes are primarily used for line controlling, chemical injection and sub-sea safety valves. The Chemical Process and Instrumentation industry also has typical applications requiring seamless pipes, including steam & heat trace bundles, flow measurement & sensing and fluid & gas transfer. Small-diameter pipes are trusted choices for GC, gas chromatography, or HPLC high-performance liquid chromatography tools. The manufacturers now need small samples to be processed at high speeds; The seamless stainless-steel capillary is used for plumbing many high-precision systems. 

Newer applications for hydraulic seamless coil pipes include compressed natural gas transfer for vehicle refueling and hydrogen transport for material handling applications. In the applications, seamless pipes save time and effort as they need multiple fittings. These pipes are also required in other industries, such as Aerospace & Defense, Alternative Energy, Shipbuilding, and Health Care.  

  1. Seamless coil is available in different forms & lengths 

Did you know that the most extended seamless coil can stretch 6,926 feet? This is approximately 5.5 times the height of the Empire State Building of New York. Seamless pipes are available in several corrosion-resistant and high-performance alloys and size ideal for ultra-high purity, military, aircraft, semiconductor, medical and general instrumentation applications. Depending on the application and needs, this is available in straight and coil form.