We are professional High Frequency Welding Studded Tubes manufacturer. Studded Pipes for HRSG refinery, furnaces, Air Cooler, boiler, gas turbines, fired heaters, Fluidized Bed Coils.
What are Studded Tubes?
These are metal tubes with studs welded on the OD throughout the length in a specific pattern, and used in fired heaters in refineries and also in water tube boilers.
High density crude oil is passed through studded tubes which are heated from outside. Liquefied product comes out from the other end, which now can be used for further processing.
At times, navy boilers also require studded tubes, with oval shaped studs welded on them. These are used for heating water in water tube boilers.
Advantages of Studded Tubes
To increase the surface area of the tube and to protect tube surface from direct exposure to heat corrosive environment
Studding reduces the amount of bare pipes used in these processes. Heat transfer surface of one studded pipe is equivalent to surface of 4 to 10 bare pipes.
Use of studded tubes is ideal for processes / applications, where dirty fuels are used in harsh environments
At TS, studding is done by resistance welding machine. The linear and angular pitch is precisely maintained by PLC controller. Studs are welded on tubes having diameter from 4" to 8" and length maximum upto 12 meters.
Pipe materials – We use tube materials as Mild Steel or Alloy Steel like grades P3, P5, P9, P11 etc. Stud Material is generally Mild Steel or as per customer requirement.
Studded tubes are manufactures and tested as per Standard SH/T 3422-2011
Production of studded tubes
The steel studs are automatically resistance welded to the tube, producing high quality forge welds. The welding process enables the combination of any grades for studs and tube: carbon, low alloy, stainless steels and high nickel alloys. Alloy steel pipes are stress-relieved after studding, according to the relevant specifications for the class and grade of steel used.
Because of their relative easy of cleaning, studded tubes or nail head pipes are used in furnaces and fired heaters as an alternative to high frequency welded finned tubes wherever the process application is such that heavy fouling of the external surface may occur.
The studs are attached to the pipe in diametrically opposing pairs around the circumference by electrical resistance welding to ensure a high
integrity bond for strength and heat flow. Stud diameter, height and pitch can be specified on an individual basis.
Test of studded tubes
Welding tests are carried out as a matter of course to ensure the effectiveness of the stud to pipe bond. Heat treatment of the completed studded tube is carried out where necessary. Should fouling eventually reduce the process performance of the equipment, the studded surface can be
cleaned efficiently by shot blasting without damage to the materials.
An electric current is applied by connect on the stud and tube and theresistance in this circuit produces the heat necessary for welding. Maximum resistance and therefore maximum heating occurs at the interface Between the Stud and the tube. Pressure to forge the Stud and the tube together at the point of maximum heating is applied by various forms of tooling. These resistance welding processes produce a strong metallurgical bond between the stud and the tube while minimizing the heat affected zone (HAZ) in the tube. The use of pressure to forge the fin and the tube together helps to minimize the heat input necessary to make the weld. This Product is used in Fired Heaters under Very High Pressure & Temperature mainly in Petroleum refineries.
Studding of pipes up to 8 inch dia and stud diameter up to 18mm can be supplied in Carbon steel, alloy steel and stainless steel pipes.
Advantages of Steel studs :
1)Satisfying connection surface, little heat loss .
2)Welding connection rate higher than 90 percent.
3)No need of welding power, hardly any welding tumor .
4)Narrow heated zone on the surface, no melted pool, without destroying the tissue of basic tube.
5) Welding parameters are strictly set to ensure the quality of bulk studded tube and avoid the instability of manual operation
For a rapid quotation requested following information,
Base tube : Diameter, thickness, length and material specification and whether ends are plain or weld prepped.
Studs : Diameter, length or height, number per circumferential row/or circumferential pitch, plus vertical pitch and material specification.
Number of rows of studs and plain end length
Fields of Application:Furnaces, Chemical Petrochemical-Industry, Power stations etc. where liquid media under high pressure are to be heated or cooled.
Advantages: Due to their high rigidity, studded pipes can be used even under extreme temperature and pressure conditions.
Manufacturing Process: Studs are fully automatically welded onto the tubes (pipes) by resistance welding.
Materials: Base tubes (pipes) & Studs Carbon Steel Low Alloy Steel Stainless Steel
Length: Up to 30 meters. If necessary with circumferential weld, 100% x-rayed. If required pressure tested.
Studs: General Stud spacing 1/8" (16mm) = 63 Stud rows per meter
Type of Studs: Cylindrical , elliptical or lens type studded pipes
Uses of Studded Tubes
Steel studded tubes are used instead of finned tubes for heat transfer in the petrochemical industry, generally in furnaces and boilers where the surface is exposed to a very corrosive environment and where very dirty gas streams require frequent or aggressive cleaning.
Pin tubes (pin finned tubes,pin fin tubes)
Pin fin tubes (fin tubes) is a high thermal efficiency heat transfer fin tubes (fin tubes). Using helically wound copper wire, the external fins is mechanically bonded to the base tubes (pipes) via solder. Pin fin tubes (fin tubes) is suitable for a wide variety of air-blast cooling applications including process liquids and gasses, oil, diesel fuel, high pressure water and steam. Pin fin tubes can be manufactured using a variety of base tubes (pipes) materials including copper, brass, copper/nickel, brass, carbon steel and stainless steel.
Wire wound internal turbulators are added to enhance thermal performance for viscous fluids such as oil, and for certain gasses, including compressed air and steam.
As the density of the external fin and internal turbulator are variable, Pin fin tubes (fin tubes) can be readily optimized to suit individual applications. This product is fully integrated into Air Radiators standard range of heat exchanger packages, and is also available as loose tubes.
Pin tubes (pin finned tubes,pin fin tubes)intensified heat-transfer component, as a kind of new type heat-transfer component, owns several main advantages as follows. Firstly, no matter the fume scours away tubes (pipes) bundle broadways or lengthways, all of aciculiform extended surface are scoured by fume turbulent flow broadways and airflow forms steady-state whirlpool and reversed-flow region symmetrical to each other behind column back of needle rib. As thermal boundary layer is constantly destroyed and re-form after destroy, the whole heat-transfer surface boundary layer thins down and then thermal resistance reduces, heat-transfer coefficient enhancing greatly as a consequence. Secondly, as Pin tubes (pin finned tubes,pin fin tubes)is a kind of cantilevered structure, under the impact effect of airflow, needle rib will vibrate, making fume difficult to accumulate on the tube, plus intense turbulent-flow scouring of fume, Pin tubes (pin finned tubes,pin fin tubes)intensified heat-transfer component is endowed with stronger self-cleaning capacity. In addition, owning compact structure, low unit heat-interchange quantity and metal consumption, Pin tubes (pin finned tubes,pin fin tubes)is a kind of recommendable intensified component.
Steel studs are welded by a special process onto the base tube. Studded Tubes are used to increase the Surface Areas to achieve higher Heat Transfer Rates. They are used in Fluidized Bed Coils and Fluidized Bed Superheaters. They are also used in Refineries as Reheaters.
We use Automatic Stud Welding Machines using Drawn Arc method capable of welding studs up to max. 13mm Dia. at a very closed pitch of 63 Stud Planes Per Mtr. (cross-linear). The Material Grade of Studs and Tubes can be similar or dissimilar of grades ranging from Carbon Steel to Alloy Steel (up to 9 Cr) to Stainless Steels. We can also give special HVOF Chromium Carbide coating on surfaces subjects to High Erosion Velocity of Flue gases to avoid frequent replacements.