Stainless Steel Electropolished Pipes

AlloySteelTubes

 

 

 
ISPAT ALLOYS & TUBE INDUSTRIES is one of the most trusted pipes & tubes supplier worldwide having a brand image that has been recommended by the big names in the business. Electropolished Stainless Steel tubes and pipes are found in a wide variety of applications, ranging from the equipment and systems used by the processing industries to structural and ornamental end-uses, as well as in consumer-oriented products, e.g., the exhaust systems for Dairy industries, Drugs and Pharma industries, Chemical Industries, Sugar Industries, Biotechnology, Food and Beverage industries, Automobiles and motorcycles. Both round and square stainless steel tubes, as well as stainless steel pipes, are used for structural applications. Ispat Alloys & Tubes Industries manufacture these materials used in the processing industries.
 
     
 
Tubes are usually designated by its’ outside diameter (OD) and wall thickness, in contrast to pipes, which is controlled by the inside diameter (ID). Sanitary tubes, which is frequently required in high purity systems used by the processing industries, is available with ODs ranging from 0.5 inches to 6 inches and walls of thickness nominally 0.065 to 0.120 inches. In the applications of tubes and pipes, the smoothness of the surfaces of those components is often important, particularly the interior surfaces that contact the process fluids in the process systems. Ispat alloys and Tubes Industries has developed the capability to polish the interior and exterior surfaces of tubes and pipes with larger diameters, a service that is not readily obtained from standard tubing vendors.
 

 

The Fabrication of Stainless Steel Tubing

 

 
There are two categories of tubular products — welded and seamless — and each has advantages and disadvantages. Welded tubing may be fabricated from either a hot or cold rolled coil of steel, the latter providing closer tolerances, excellent mechanical properties and a fairly smooth surface finish. The coil is slit into precise widths and then processed into tubing through a series of forming, welding, sizing and cutting operations. Orbital tig welding, automated orbital welding or laser welding may be used to fabricate the tubular materials. It is claimed that laser welding offers advantages for high purity requirements, minimizing rouging, weld slag and weld porosity.
 
     
 
Seamless tubing is made from metal bar using one of three methods, i.e., either piercing, extrusion or gun-drilling. Piercing involves the controlled tearing of a hot metal bar and ironing of the sides of the hole and the method is limited to stainless steel alloys containing less than 12% chromium. Extrusion requires forcing the metal bar through a die over a mandrel and is the most widely used method of fabricating tubular materials, although there are problems with eccentricity and surface imperfections. Gun-drilling is believed to produce a higher quality product, but a more expensive method. In this method the metal bar is rotated as it is fed over a stationary, flute drill, the metal chips being flushed from the cavity to allow immediate inspection for straightness and concentricity. The tubular products often require further processing to reduce the tube hollow for dimensional or metallurgical reasons. Cold-drawing is a tensile operation in which the tube is pulled through a die to reduce its’ diameter or change its’ shape. Cold-pilgering requires compression of the tube to simultaneously reduces the outside diameter (OD), the inside diameter (ID) and the wall thickness.
 

 

Stainless Steel Tubing in the Process Industries

 

 

 
The process equipment used by the chemical, pharmaceutical, biotechnology, dairy, food and beverage industries and by water treatment facilities is fabricated from the austenitic stainless steel alloys. These alloys provide the required corrosion resistance, thermal and chemical stability and represent a versatile and cost effective choice for materials of construction. The tubing and/or piping, an integral part of a process system, is presently fabricated to meet the following industry standards;
 
     
 
(i) ASTM A249 / ASME SA 249, which specifies pressure tubes made from the stainless steel alloys 304, 304L, 316, 316L, 317 and 321; (ii) ASTM A269, which defines the nominal wall thickness for tubing in general service; (iii) ASTM A270, which describes seamless and welded austenitic stainless steel sanitary tubing, required by the dairy, food and beverage industries, with closer tolerances than those specified in ASTM A269. This standard has been established to provide the closer alignment of tube to tube and tube to fittings necessary for automated orbital welding. (iv) ASTM A312 / ASME SA312, which specifies the tubing and/or piping to be used in high temperature and general corrosive service.
 

 

The Demand for High Purity Process Systems

 

 
There is a growing demand for processes to be completed under controlled, hygienic conditions and to incorporate CIP (clean-in-place) and SIP (sterilize-in-place) systems, particularly in the pharmaceutical, biotechnology, food and dairy industries. This concern for high purity is reflected in the demand for smooth, Electropolished surfaces for all components in the process system, with particular attention being paid to the interior surfaces, i.e., the surfaces that are in contact with the fluids and products. Corrosion processes are slower at smooth surfaces and contamination of the process fluids and products that contact those surfaces is therefore minimized. Again standards have been established that define “sanitary tubing.” The requirements for any Electropolished metal tubing used in the process equipment or process system are discussed in publications such as
 
     
 
(i) Sanitary Standards for Electropolished Metal Tubing for Dairy Products, Number 33-00, and (ii) 3-A Accepted Practices for Permanently Installed Product and Solution Pipelines and Cleaning Systems used in Milk and Milk Product Processing Plants.
 

 

Corrosion and Surface Smoothness

 

 
The rate of corrosion of a metal or metal alloy is dependent upon several factors, an important one being the real surface area that is exposed to the fluids in the process system. Roughness increases the real surface area and therefore the rate of corrosion. Conversely, the smoother the surface, the lower is the real surface area and the lower is the rate of corrosion. A smooth, Electropolished surface, particularly an interior surface that contacts the products, provides other advantages;
 
 
(i) it minimizes the number of sites available for microbial growth, (ii) it reduces turbulence in the fluid flow, (iii) it minimizes the adherence of particulate matter to that surface, and (iv) it allows more efficient and reproducible cleaning and disinfection.
 

 

Electropolished Stainless Steel Tubing

 

 
The metal or alloy surface may be Electropolished by either chemical or mechanical treatments, or by electropolishing. Both the interior and exterior surfaces of stainless steel tubing can be Electropolished mechanically, typically using 120, 150 or 180/220 grit. As the grit number is increased, a smoother surface is obtained. Surface scale and other discolorations, resulting from the heat treatments and other processing used to produce the stainless steel, are removed by chemical treatments. This involves immersioin of the tubing in “pickling baths,” which are mixtures of aqueous solutions of nitric acid and hydrofluoric acid or a solution of citric acid. This treatment is typically carried out at temperatures ranging from 25 to 45ºC. Electropolishing is a process by which metal is removed by passage of an electric current, with the tubing immersed in an electrically conductive solution, usually an aqueous solution. Metal is removed at a rate that is proportional to the applied current. The amount of metal electrochemically dissolved is dependent upon the electrolyte, temperature, current density (which is itself dependent upon the real surface area) and time.
 
     
 
For high purity requirements electropolishing offers significant advantages over mechanical surface treatments and is more versatile than the chemical treatments. The surface obtained by electropolishing is very smooth and has been brightened, stress relieved, cleaned and deburred. It has been shown that the electrolytes used in this process enhance the formation of the passive film at the metal or alloy surface, a film that protects the steel substrate by inhibiting general corrosion. Mechanically Electropolished surfaces contain scratches, strains, metal debris and embedded abrasive particles. Furthermore, the cold working that accompanies grinding and polishing operations penetrates into the bulk metal to decrease tensile strength.
 

 

Other Applications of Stainless Steel Tubing

 

 
Stainless steel tubing is also widely used in structural and ornamental applications and here either square or round tubing may be selected. Presently, within the processing industries, there is considerable interest in modular process systems and the frames that support the process equipment are fabricated from stainless steel tubing. Another example of a structural application is the design and fabrication of the handrails on platforms, catwalks, stairways and ladders in manufacturing facilities. The exterior surfaces of the tubing are usually Electropolished and smooth to avoid injury to the hands of operators, or other personnel using the platforms and stairways. There is also an aesthetic value to the Electropolished (shiny) appearance of the handrails or tubular frames.
 

 

How is Ispat Alloys & Tube Industries Involved
with Electropolished Tubing and/or Piping?

 

 
The metal or alloy surface may be Electropolished by either chemical or mechanical treatments, or by electropolishing. Both the interior and exterior surfaces of stainless steel tubing can be Electropolished mechanically, typically using 120, 150 or 180/220 grit. As the grit number is increased, a smoother surface is obtained. Surface scale and other discolorations, resulting from the heat treatments and other processing used to produce the stainless steel, are removed by chemical treatments. This involves immersioin of the tubing in “pickling baths,” which are mixtures of aqueous solutions of nitric acid and hydrofluoric acid or a solution of citric acid. This treatment is typically carried out at temperatures ranging from 25 to 45ºC. Electropolishing is a process by which metal is removed by passage of an electric current, with the tubing immersed in an electrically conductive solution, usually an aqueous solution. Metal is removed at a rate that is proportional to the applied current. The amount of metal electrochemically dissolved is dependent upon the electrolyte, temperature, current density (which is itself dependent upon the real surface area) and time.
 
     
 
For high purity requirements electropolishing offers significant advantages over mechanical surface treatments and is more versatile than the chemical treatments. The surface obtained by electropolishing is very smooth and has been brightened, stress relieved, cleaned and deburred. It has been shown that the electrolytes used in this process enhance the formation of the passive film at the metal or alloy surface, a film that protects the steel substrate by inhibiting general corrosion. Mechanically Electropolished surfaces contain scratches, strains, metal debris and embedded abrasive particles. Furthermore, the cold working that accompanies grinding and polishing operations penetrates into the bulk metal to decrease tensile strength.
 

 

Our Best Selling Electropolished Pipes

 

                     
  • Electro Polish
  • Matte Polish
  • Mirror Polish
  • Glossy Polish

 

 

 

304 Stainless Steel Electropolished Pipes

 

 

 

Electropolished Tubes

 

 

SPECIFICATION :
Sr. No. Material Size Schedule Specification
1 Seamless Pipe 15 NB To 300 NB Sch. 5s Sch. 10s Sch. 40s Sch. 80s Sch. 160s Sch. XXS ASTM A 312
2 Welded (ERW) Pipe 15 NB To 300 NB Sch. 5s Sch. 10 Sch. 40s & Sch. 80s ASTM A 312
3 Welded (ERW) Pipe; 150 NB To 600 NB Sch. 5s Sch. 10s Sch. 40s & Sch. 80s ASTM A 358

 

 

Chemical Composition

 

SS
304
304N
304LN
Ni 8 – 11 8 – 11 8 – 11
Fe Balance Balance Balance
Cr 18 – 20 18 – 20 18 – 20
C 0.08 max 0.08 max 0.035 max
Si 0.75 max 0.75 max 0.75 max
Mn 2 max 2 max 2 max
P 0.040 max 0.040 max 0.040 max
S 0.030 max 0.030 max 0.030 max
N
0.10 – 0.16
0.10 – 0.16

 

 

Specifications

 

Stainless Steel [SS] 304 / H / L / N / LN
AISI 304 / 304H / 304L / 304N / 304LN
UNS S30400 / S30409 / S30403 / S30451 / S30453
Werkstoff Nr. 1.4301 / 1.4306 / 1.4948 / 1.4311

 

 

Mechanical & Physical Properties

 

Density 8.0 g/cm3
Melting Point 1400 °C (2550 °F)
Tensile Strength Psi – 75000 , MPa – 515
Yield Strength (0.2%Offset) Psi – 30000 , MPa – 205
Elongation 35 %

 

 

 

316 Stainless Steel Electropolished Tubes

 

 

 

Electropolished Tubes 316

 

 

Specification

 

Grade UNS No Old British Euronorm   Swedish SS Japanese JIS
    BS En No Name    
316 S31600 316S31 58H, 58J 1.4401 X5CrNiMo17-12-2 2347 SUS 316
316L S31603 316S11 - 1.4404 X2CrNiMo17-12-2 2348 SUS 316L
316H S31609 316S51 - - - - -

 

 

Chemical Composition

 

Grade   C Mn Si P S Cr Mo Ni N
316 Min - - - 0 - 16.0 2.0 10.0 -
Max 0.08 2.0 0.75 0.045 0.03 18.0 3.0 14.0 0.10
316L Min - - - - - 16.0 2.0 10.0 -
Max 0.03 2.0 0.75 0.045 0.03 18.0 3.0 14.0 0.10
316H Min 0.04 0.04 0 - - 16.0 2.0 10.0 -
Max 0.10 0.10 0.75 0.045 0.03 18.0 3.0 14.0 -

 

 

Mechanical Properties

 

>
Grade Tensile Str(MPa) min Yield Str0.2% Proof(MPa) min Elong(% in 50mm) min Hardness Rockwell B (HR B) max Brinell (HB) max
316 515 205 40 95 217
316L 485 170 40 95 217
316H 515 205 40 95 217

 

 

Physical Properties

 

Grade Density(kg/m3) Elastic Modulus(GPa) Mean Co-eff of Thermal Expansion (µm/m/°C) Thermal Conductivity(W/m.K) Specific Heat 0-100°C(J/kg.K) Elec Resistivity (nΩ.m)
316/L/H 8000 193 15.9 16.3 500 740

 

 

Uses & Applications

 

 

The process equipment used by the chemical, pharmaceutical, biotechnology, dairy, food and beverage industries and by water treatment facilities is fabricated from the austenitic stainless steel alloys. These alloys provide the required corrosion resistance, thermal and chemical stability and represent a versatile and cost effective choice for materials of construction.

 

 

                     
  • Dairy Industries
  • Chemical
  • Petrochemical
  • Refineries
  • Fertilizers
  • Power Plant
  • Nuclear Power
  • Oil & Gas
    
  • Paper
  • Breweries
  • Cement
  • Sugar
  • Oil Mills
  • Mining
  • Construction
    
  • Shipbuilding
  • Steel Plant
  • Offshore
  • Defence
  • Ports
  • Railway
  • Engineering Co. & Government Org. etc

 

 

 

Send Enquiry

Contact Info

Call us on +91 79774 35863 (Rakesh Jain) | Email us on info@ispatalloy.com

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Head Office : 33/35, Damodar Bhavan, Shop No-2, 1st Paraswadi Lane, V P Road, Mumbai, Maharashtra 400004