Galvanized Steel Pipe Vs black steel pipe

What is a Galvanized Steel Pipe?

Galvanized steel pipe is a steel pipe that has been coated with zinc. This coating protects the steel from corrosion. It is most commonly used for outdoor construction like fences and handrails, or for some interior plumbing. It is also sometimes called galvanized iron pipe. Galvanized steel pipe has been coated with a layer of zinc. The zinc provides a barrier against corrosion so that the pipe may be exposed to the outdoor environmental elements. The protective barrier proves equally effective against damage from indoor humidity.

History of Galvanized Steel Pipe

The process of galvanization was first discussed by scientists in the 1770s, nearly 60 years before it was finally introduced in the 1830s. French engineer Stanislaus Tranquille Modeste Sorel took out the first patent for the process in 1937, and began manufacturing it soon after. By the 1850s, Europe was producing galvanized steel out of manufacturing plants located around the continent. The United States followed shortly thereafter, opening its first plant in the 1870s.

To create galvanized steel pipe, steel materials are placed into a molten bath of zinc. This process is also called hot dip galvanization. The two metals are chemically bound to one another in this process, and will therefore never separate, resulting in a more resistant and longer lasting version of steel.

Uses of Galvanized Steel Pipe

Galvanized Steel Pipe is used in a variety of settings. Until about 30 years ago, galvanized steel was utilized for water supply pipes in construction. It is used in outdoor applications wherever the strength of steel is desired, such as fence posts and rails, scaffolding and as protective railings.

The common trouble in using

When used as water pipe, the zinc barrier coating tends to react to the minerals in the water, often causing plaque to build up inside of the pipe. This impedes the water flow and, in severe cases, may lead to burst pipes. Galvanized piping is connected with threaded fittings that may also introduce leaks into the plumbing if not properly fitted.

Types of galvanized

There are a number of methods of applying zinc coatings and each will determine the coating’s thickness and its ultimate durability in a specific environments The most commonly encountered types of zinc coatings are:

  • Zinc electroplating
  • Mechanical plating
  • Continuously galvanized sheet
  • Continuously galvanized wire
  • Galvanized pipe and tube
  • General or hot dip galvanizing

What is Hot-Dip Galvanizing?

Hot dip galvanizing steel pipe with threaded end

Hot-dip galvanizing (HDG), as referenced is the process of dipping fabricated steel into a kettle or vat of molten zinc. While the steel is in the kettle, the iron metallurgically reacts with the molten zinc to form a tightly-bonded alloy coating that provides superior corrosion protection to the steel.
Hot-dip galvanizing is a form of galvanization. It is the process of coating iron, steel or aluminum with a thin zinc layer, by passing the metal through a molten bath of zinc at a temperature of around 860 °F (460 °C).

Defects of hot dip galvanized pipe

Galvanized Steel are those steel that has been covered with a layer of zinc metal.

In the production process and packaging process of hot dip galvanized, the appearance of hot dip galvanized steel strip and steel plate may occur following defects.

The excess liquid zinc from galvanized pot on the strip surface, which excess liquid zinc air knife blow to control the zinc coating thickness. Gas pressure of the air knife, air knife and strip pitch, strip speed will directly affect the thickness of the zinc layer. If the lack of supply instability of the air knife or air knife pressure can cause the accumulation of zinc coating, ie, zinc scar. 

Purity of zinc coating is not enough, the original board surface dirt eclipse biological treatment is not sufficient and form the residue when copper, iron, arsenic and other impurities is higher levels of zinc coating. galvanized uncoated can easily lead to the surface of the steel dark spots. Galvanized steel surface exposed to moisture or rain immersion lead to zinc oxide and produce a white powder at a certain temperature. The surface of white rust corrosion resistance is greatly reduced and affect its use. 

Galvanized sheet surface zinc layer is rugged and uneven thickness, or even the surface of small particles. because the air knife is is aspirated uneven when hot dip galvanized or improper air knife and strip spacing.

Hot galvanized plate surface defects

Hot galvanized plate is a long Word plate, hot galvanized plate has a lot of advantages, but there will be some drawbacks corresponding. Manufacturers from galvanized sheet production to the store will have some drawbacks.

1, Galvanized layer off: off the main reasons many, including zinc coating surface oxide, silicon compounds, cold rolling emulsion dirty, the OF segment oxidizing atmosphere and shielding gas dew point is too high strip wok temperature partial low, so many factors can cause the shedding of the zinc coating.
2, there will be a white embroidered and the formation of dark spots: spots is a result of the further oxidation of white embroidery. White embroidered causes of a passivation film thickness enough or uneven; B, the surface of the galvanized steel sheet does not have an oil coating or coiling the strip surface residual moisture; c, passivation is not completely dried; transport or storage in damp or dry in the rain; e finished storage time is too long; f, galvanized sheet and other acid and other corrosive media contact or stored together. Finished in the library most common can only be stored for three months, put the long time oxidation.
In addition to the above two points defects, as well as scratches, passivation spot, zinc tablets, webbing, air knife streak, air knife scratches, exposed steel, inclusions, mechanical damage, poor performance steel base side of the wave, buckling substandard size, imprint, zinc layer thickness clashes, such as roller printing defects.

Galvanized sheet in a lot of industries are likely to use, not the same flaws exposed in different industries, such galvanized sheet prices also may differ, but I believe that we will in the future continue to progress to make up for these deficiencies.

Quality defects of galvanized layer

In recent years, with the surface quality continuous improvement of hot dip galvanized, the coating quality of the galvanized sheet has also been greatly improved.

However, as cars and appliances of the two industries need high-grade galvanized steel sheet, which still have to solve the substrate surface contamination and uncoated points affect the quality of the galvanized coating.

Composition and source of a substrate surface contaminants

Hot dip galvanized substrate surface covered with a layer of black sludge pollutants. A mixture of contaminants from solids such as oil and iron particles, which about 30% to 50% iron and non-metallic solids. The hot rolled strip in a high-speed cold rolling process, part of the iron off from the surface of the roll and strip surface into the emulsion, contamination of the emulsion, the other part is stuck in the strip surface. In the strip rolling process, in addition to the emulsion due to the formation of high-temperature emulsion breaking film lubricant, as well as a small amount of oil residues in the strip surface and iron powder mixed pollutants, firmly glued to the strip surface. exports were unlikely to be blowing in the mill washed off.

Set layer type of quality defects

The types of defects that affect the coating quality can be broadly divided into:

  1. surface contamination;
  2. growth between the bump and metal compounds;
  3. uncoated point;
  4. embedded in people coating of zinc slag particles;
  5. pit;
  6. zn-Fe crystal growth in the coating.

Cold galvanized (galvanizing)

Cold galvanized(galvanizing) also called electro-galvanized cold galvanizing, which is the use of the pipe member through electrolysis degreasing, pickling, and put into a solution composed of zinc and a cathode connected to the electrolytic apparatus, placed opposite the tube member zinc plate, connected to the electrolysis the positive power equipment, the use of electric current from the positive to the negative directional movement will be in a layer of zinc deposited on pipe fittings, cold-plated fittings are galvanized after processing the first.

Cold galvanizing paint mainly through electrochemical principles for corrosion, it is necessary to ensure full contact of zinc powder and steel, generating electrode potential difference, so the steel surface treatment is very important.

Cold galvanizing process is used to protect the metal against corrosion, for the use of filler coatings of zinc, in the use of any method to a coating applied to the surface to be protected, the filler form zinc coating after drying, the dried coating having a content of zinc (95%). Suitable for repair work (ie work in the repair process, the only damage to the steel surface to be protected place, as long as the repaired surface can be re-coated).

Cold galvanizing process for a variety of steel products and structures corrosion. (Cold galvanizing is galvanized, galvanized rarely, and only 10-50g/m2, its own hot-dip galvanized corrosion resistance than a lot of difference. Using galvanized the price is relatively cheaper.

Difference hot-dip galvanizing and cold galvanizing

Hot-dip galvanizing, it is at high temperatures the zinc ingots melt, being placed in the auxiliary material, then the metal structure is immersed in a zinc plating bath, so that the metal member attached to a layer on the zinc layer.

The hot galvanized advantage depend on its preservative ability, the better the adhesion and hardness of the galvanized layer.

Cold galvanizing is a zinc salt solution by electrolysis, to the plating on the coating, in general, which do not have heating, the amount of zinc rarely encountered humid environment is very easy to fall off. The cold galvanizing physical treatment, just in the surface brush a layer of zinc, zinc coating so easy to fall off the use of hot-dip galvanized construction.

Process of hot-dip galvanizing and cold galvanizing

Hot dip galvanized is immersed in liquid zinc dissolved workpiece degreasing, pickling, dipping, drying a certain period of time and put forward.

Cold galvanizing, also called electro-galvanized, is the use of electrolysis device to the workpiece into the composition of the zinc salt solution, after degreasing, pickling, and connecting the negative electrode of the electrolytic device; zinc plate placed at the opposite side of the workpiece is connected in the electrolytic device the positive electrode, the power is turned on, a current from the positive electrode to the negative directional movement, it will be deposited on the workpiece with a layer of zinc.

Appearance of hot-dip galvanizing and cold galvanizing

Cold galvanizing looks more smooth, bright, color passivation process plating layer is yellow-green in color, was colorful. Plating layer was bluish-white or white with white passivation process was green, white coating passivation process and the sun was significant Colorful angle. The complex workpiece angular edges parts prone to “electrical burning” from gloomy, the parts of the zinc layer thick. Yin corner site is easy to form a current dead undercurrent gray area and the area zinc layer is thinner. The workpiece overall zinc tumor, caking phenomenon.

Hot dip galvanized look a little rough compared to the electro-galvanized, silvery white, look prone process waterlines and a few drops of tumor is more obvious, especially in the one end of the workpiece. Hot dip galvanized zinc layer than a few times of the electro-galvanized thick corrosion protection is several times that of the electro-galvanized.

Hot-dipped Galvanized Steel Pipe:
Hot-dipped zinc coating is the molten metal to react with the iron matrix alloy layer. So the substrate and the zinc coating combined well. The first production step is pickling the steel pipe. 
In order to remove the surface of the iron oxide, cleaning bath by mixing an aqueous solution of ammonium chloride or zinc chloride aqueous solution for the after pickling steel pipe is needed. And then the steel pipe is allowed to put in the hot dip tank. The using advantage for hot dipped galvanized steel pipe is the coating has strong adhesion and long using life. 
Applying hot-dipped galvanizing process, the zinc coating will be combined with the surface of the steel pipe evenly. 
Production Process:
Material Inspection (Steel Pipe) — Hanging — De-greasing — Rinsing — Pickling — Washing — Dipping Fluxing — Hot Air Drying — Inside and Outside Hot-dipped Galvanizing Blow — Cooling — Passivation and Rising — Unloading — Inspection and Trimming — Type Identification — Packaging and Storing and Transportation. 
Cold Galvanized Steel Pipe:
Cold Galvanizing process is also named as electro-galvanizing process which is using cold plates as raw material. Cold Galvanized Steel Pipe has very few zinc coating which is only around 10 ~ 50 g/m2. Compared with hot-dipped galvanized steel pipe, the corrosion resistance of cold galvanized steel pipe is not as good as hot-dipped galvanized steel pipe. 
In order to ensure the quality of the galvanized steel pipe, most of the galvanized steel pipe manufacturers will not apply the electro galvanizing producing process. Only those small and outdated manufacturers still use electro-galvanizing producing process to offer relatively cheaper galvanized steel pipe. Since the zinc layer for cold galvanized steel pipe is electroplated layer, it is the individual layered zinc coating on the steel pipe, so the coating layer will be peel off easily. Overall, the producing cost for cold galvanized steel pipe is lower than hot-dipped galvanized steel pipe, and the manufacturer can offer the purchaser a very competitive market price. However, the surface of the coating is uneven which influence the corrosion resistance of the galvanized steel pipe. 
Production Process:
Uncoiling (Galvanized Steel Strips/Plates) — Leveling — Welding — Scraping the Scar — Passivation and Rinsing — Zinc adding — Setting/Forming — Type Identification — Cutting — Packing — Drying — Weighed

Types of galvanized steel pipe

Galvanized mild steel pipe

Galvanized mild steel pipe banner - Galvanized Steel Pipe Vs black steel pipe

Galvanized mild steel pipe is made of rust corrosion measures are not taken welding (welding furnaces, welding) pipe, seamless steel pipe or other metal clarinet, a certain process of hot-dip galvanizing, zinc coating to make it fit the outer coating, played long steel does not rust after processing.

Today clarinet is generally welded steel pipe welding.

Galvanized welded steel pipe used to transport require relatively clean medium, such as: water, clean air. Threaded pipe connection is a common way to connect, two hours at the factory welded pipe, pipe end with threaded and non- threaded.

In order to improve the corrosion resistance of steel tube, normally the carbon steel pipe will be galvanized. Galvanized steel is divided into hot galvanized and electro-galvanized two, thickness galvanized galvanized, electro-galvanized low cost, the surface is not very smooth. Increase the capacity of galvanized steel pipe corrosion and prolong life. Galvanized pipe is widely used, except for water, gas, oil, generally low- pressure fluid line pipe, also used oil heater oil industry in particular, marine oil wells pipes, pipelines, chemical coking equipment, condensing coolers, washing coal distillate oil exchange used tubes, as well as the bridge piles, mine tunnel support frame with a pipe.

Galvanized mild steel pipe for molten metal and iron matrix after a certain reaction with a layer of alloy layer, so that presents the effective combination between substrate and coating, and galvanized pipe can there are two ways to get, is a kind of hot dip galvanized pipe, and tprocess is the first to effective pickling of steel tube, then you can, removing fehe other is electric galvanized, hot galvanized pipe production rric oxide on the surface of the steel tube effectively will steel in ammonium chloride or zinc chloride solution after cleaning, after hot dip.

ERW Galvanized Steel Pipes

ERW Galvanized Steel Pipe banner - Galvanized Steel Pipe Vs black steel pipe

For pipes or tubes size 4 inch (10.2mm) OD and below, strip is fed into a set of forming rolls which consists of horizontal and vertical rollers so placed as to gradually from the flat strip in to a tube which is then allowed to pass the welding electrodes. The electrodes are copper disks connected to the secondary of a revolving transformer assembly. The copper disk electrodes make contact on each side of the seam and temperature is raised to the welding point. Outside flash is removed by a cutting tool as the tube leaves the electrodes, inside flash is removed either by an air hammer or by passing a mandrel through the welded tube after the tube has been cooled. This is termed as Electric Resistance Welded or ERW tube/pipe.

Steel Pipes manufacturers and Exports huge range of ERW Galvanized Steel Tubes & Steel Pipes. For pipes or tubes size 4 inch (10.2mm) OD and below, strip is fed into a set of forming rolls which consists of horizontal and vertical rollers so placed as to gradually from the flat strip in to a tube which is then allowed to pass the welding electrodes. The electrodes are copper disks connected to the secondary of a revolving transformer assembly. The copper disk electrodes make contact on each side of the seam and temperature is raised to the welding point. Outside flash is removed by a cutting tool as the tube leaves the electrodes, inside flash is removed either by an air hammer or by passing a mandnel through the welded tube after the tube has been cooled. This is termed as Electric Resistance Welded or ERW tube/pipe.

Pre-galvanized steel pipes

Pre galvanized Rectangular tubes are the industry standard for fence framework, Contractors, architects, engineers. Architects and landscape architects have used steel fencing to design a variety of shelters, lighting standards and decorative sculptures for street-scapes, parks, bus and light rail stops, shopping centers, malls, sports stadiums, office buildings, parking lots and other facilities. Steel fence post are carefully designed with clean lines, structural integrity and ease of installation. These fences are available in variety of heights and widths in multiple configurations.

pre galvanized 2 - Galvanized Steel Pipe Vs black steel pipe
Threaded galvanized pipe

Threaded galvanized pipe refers to welded tube which undergo degreasing,rush removal,phosphorization,zand drying processes before galvanization.
The treatments before galvanization allow the product to be conveniently plated with a zinc coating,and also ensure uniform coating thickness,strong coating adhesion,and improved corrosion resistance.

How to Produce this Pre Galvanized Round Pipe?

RAW Material Pre Galvanized Steel Strip - Galvanized Steel Pipe Vs black steel pipe
  RAW Material-Pre Galvanized Steel Strip

British Standard (BS1387-85) Thin thickness pipe specification
Outside Diameter (mm) Weight of Black Pipe (kg/m)
Nominal Size (DN) Screw Identifiers Maximum Minimum Thickness Plain end pipe Threaded and With Coupler
15 1/2 21.4 21.0 2.0 0.947 0.956
20 3/4 26.9 26.4 2.3 1.38 1.39
25 1 33.8 33.2 2.6 1.98 2.00
32 11/4 42.5 41.9 2.6 2.54 2.57
40 11/2 48.4 47.8 2.9 3.23 3.27
50 2 60.2 59.6 2.9 4.08 4.15
65 21/2 76.0 75.2 3.2 5.71 5.83
80 3 88.7 87.9 3.2 6.72 6.89
100 4 113.9 113.0 3.6 9.75 10.0
Normal steel pipe size
Outside Diameter (mm) Weight of Black Pipe (kg/m)
Nominal Size ( DN) Screw Identifiers Maximum Minimum Thickness Plain end pipe Threaded and With Coupler
15 1/2 21.7 21.1 2.6 1.21 1.22
20 3/4 27.2 26.6 2.6 1.56 1.57
25 1 34.2 33.4 3.2 2.41 2.43
32 11/4 42.9 42.1 3.2 3.10 3.13
40 11/2 48.8 48.0 3.2 3.57 3.61
50 2 60.8 59.8 3.6 5.03 5.10
65 21/2 76.6 75.4 3.6 6.43 6.55
80 3 89.5 88.1 4.0 8.37 8.54
100 4 114.9 113.3 4.5 12.2 12.5
125 5 140.6 138.7 5.0 16.6 17.1
150 6 166.1 164.1 5.0 19.7 20.3
Hot dip galvanized square tube

Hot dip galvanized square tube banner - Galvanized Steel Pipe Vs black steel pipe

Hot dip galvanized square tube is used square tube plate or strip after curl forming in the hot dip galvanized pool through a series of chemical reactions forming the square tube; can also be hot-rolled or cold rolled galvanized steel strip after colda hollow square cross-section bend, then the high-frequency welded steel pipe.

Hot dip galvanized square tube has good strength, toughness, ductility and welding process performance and good ductility, the alloy layer with steel base attached to a solid, hot dip galvanized square tube can be cold punching, rolling, drawing a variety of molding and bending without damage to the coating; for general processing such as drilling, cutting, welding, cold bending process. Hot dip galvanized surface bright and beautiful, according to the demand for engineering. 
Hot dip galvanized square tube is often used: glass curtain wall, Tower of power, communications, power grids, water and gas transmission, wire casing, housing, bridges, metal structure, power transmission, etc.

Galvanized Seamless tube

Galvanized seamless tube banner - Galvanized Steel Pipe Vs black steel pipe

Seamless steel pipe is with a wide range of applications in our construction industry. In general, Galvanized seamless tube is the hot dip galvanized and electro-galvanized two categories.

The first to introduce hot-dip galvanizing, including wet, dry the, lead, zinc, oxidation-reduction method, etc., the process is very complex, the need for technical maturity to complete. Steel Pipe acid leaching after cleaning, the specific method used to activate the surface of the tube improve the quality of zinc, is not the same, hot dip galvanized main difference.

I do not know understand if understand the electro-galvanized zinc coating surface and compared to a very smooth and dense, homogeneous; the characteristics of the electro-galvanized with good corrosion resistance and mechanical properties; Production is now mainly used in dry and oxidation-reduction method. Coating on one side, the internal and external surfaces of the thickness of the coating on different double-sided smooth coating, and thin-walled tube galvanized to complete this method.

Zinc consumption 60% to 75% lower than the hot-dip galvanizing. Electro-galvanized in the operation of technical and general than there is a certain complexity, which requires high technology and conditions in order to complete.

Hot dip galvanized coating - Galvanized Steel Pipe Vs black steel pipe

The technical requirements of galvanized steel pipe

hot dip galvanized pipe - Galvanized Steel Pipe Vs black steel pipe
Galvanized Steel are those steel that has been covered with a layer of zinc metal.

Steel mechanical properties is an important index to ensure that the steel eventually use performance, it depends on the chemical composition of the steel and heat treatment system

The technical requirements galvanized steel pipe should reach.

  • Grades and chemical composition. Galvanized steel grades and chemical composition shall comply with the stipulated GB3092 standard of black steel pipe steel.
  • the manufacture method: the manufacturing method of black steel pipe (furnace or electric welding) should be selected by the factory. Galvanized by hot dip galvanizing.
  • thread and pipe joint
    1. delivery of galvanized steel pipe with screws, screw thread should be done after galvanizing. And the thread should comply with the provisions of the YB822.
    2. steel pipe joint shall comply with the terms of YB238; Malleable iron pipe fittings shall comply with the terms of YB230.
  • the mechanics properties: the mechanical properties of steel tube before galvanized should comply with the provisions of the GB3092.
  • the uniformity of the galvanized layer: the galvanized steel pipe should be carried out galvanized layer uniformity test. Steel tube specimens in the copper sulfate solution dipping 5 consecutive shall not become red (copper plating color).
  • the nominal diameter of cold bending test no greater than 50 mm galvanized steel pipe should carry out cold bending test. Bending angle is 90°, bending radius is 8 times the diameter. Without padding when testing, sample welds should be placed in the bending direction of the lateral or upper. After the testing, the sample should not have cracks and zinc layer peeling off with the elephant.
  • hydrostatic test: water pressure test should be performed in the black steel pipe, eddy current flaw detection can also take place of hydrostatic test. Test pressure or eddy current inspection shall comply with the terms of GB3092 contrast sample size.

In the steel tube standard, according to different application requirements, the tensile strength, yield strength or yield point, elongation and hardness, toughness index are all stimulated, and even the user’s high, low temperature performance, etc.

Galvanized pipe process characteristics

Zinc sulfate biggest advantage is the current efficiency of up to 100%, the deposition rate, which is the other galvanizing process unparalleled.

Galvanized pipe process characteristics:

1 zinc sulfate optimization

As the crystalline coating is not detailed enough, dispersing ability and poor throwing power, and thus is only suitable for simple geometries such as pipe and wire plating. Sulfate galvanized iron alloy craft of traditional sulfate galvanizing process optimization, leaving only the main zinc sulfate salt, and the remaining components are discarded. In the process of forming a new recipe and adding the right amount of iron, so that the original single-plated zinc alloy metal plating layer is formed. Reorganization process, not only to carry forward the original process high current efficiency, fast deposition rate advantages, but also the dispersion ability and throwing ability has been greatly improved in the past can not be plated complex parts, simple and complex parts can now plated and protective properties increased by 3 to 5 times faster than a single metal. Practice has proved that for wire, pipe continuous plating, coating the grain is more refined than the original, more bright, fast deposition rate. Within 2 ~ 3 min coating thickness to meet the requirements.

2 Zinc sulfate conversion

Sulfate zinc sulfate zinc alloy to retain only the primary zinc sulfate salt, the remaining components such as aluminum sulfate, alum (potassium aluminum sulfate), etc. can be processed in the bath, was added sodium hydroxide so as to precipitate an insoluble removal; organic additives, then add powdered activated carbon adsorption removed. Tests showed that aluminum sulfate and aluminum potassium sulfate is difficult to completely remove the one-time, affect the brightness of the coating, but not serious, may be accompanied by the consumption, the brightness can be restored at this time plating solution through the processing, according to new techniques additional ingredients required,to complete the conversion. 

3 deposition rate, excellent protection performance

Sulfate galvanized iron alloy craft up to 100% current efficiency, fast deposition rate is unmatched in any galvanizing process, speed fine tube 8 ~ 12 m / min, the average coating thickness 2m/min, it is difficult to continuous galvanizing achieved. Bright coating delicate eye. According to national standards GB/T10125 “test in artificial atmospheres – Salt spray test” method of testing, 72 h, plating intact, unchanged; 96 h, coating the surface of a small amount of white rust. 

4 unique clean production

Galvanized pipe with galvanized iron alloy sulfate process lies between the trough and the trough are perforated production straight out and no solution or overflow. Each step of the production process from the circulation system components, i.e. the alkali solution tank solution, plating solution, and the passivation fluid, light, not only by the outer loop back leakage or discharge system, located only 5 line cleaning tank, cyclic reuse periodic emissions, especially after the production process without passivation without cleaning the wastewater generated. 

5 Particularity of electroplating equipment

Electroplated galvanized pipe with wire plating, as are all continuous plating, but different plating equipment. Wire with its characteristic elongated strip designed plating tank, the tank is long and wide but shallow. Electroplating wire from the hole piercing, showing a shape in the liquid started to keep distance from each other. Unlike wire and galvanized pipe but has its unique slot equipment is more complex.

The tank by the upper and lower parts, the upper part of the plating tank, the lower part of the storage solution circulation tank, the narrow width forming a shape similar to the trapezoidal grooves in the plating bath has a channel running plated galvanized pipe, There are two holes in the bottom of the storage tank is connected to the lower, and the formation of the bath round robin system and sump pump. Therefore, galvanized pipe with wire plating as plating are dynamic in nature, with the difference between the wire plating, plating bath galvanized pipe is dynamic nature.

Galvanized Steel Pipes are widely used in many fields, do you kown the reason why is so popular?

Below is three main using advantages of Galvanized Steel Pipes you might want to know:

1. After being hot-dip galvanized, the pipes of the surface will be protected well. Compared with other type of coating process, deepen the zinc is easier to let the coating covered well.

2. Because the zinc coating has a larger hardness value than steel pipes. After being galvanized, the impact resistance and anti-ware properties of the steel pipes has increased. 

3. In general, the zinc layer at the pipe ends will be relatively thicker than other type of coatings. Therefore, it offers better toughness and abrasion resistance to the Galvanized Steel Pipes. 

How should paint galvanized steel pipe?

hot dip galvanized pipe - Galvanized Steel Pipe Vs black steel pipe

When galvanized pipe painted, you must use professional equipment to complete the necessary steps.

The process includes the following steps: passivation steps, washing steps; painted steps; curing step in front of the painting steps with drying preheating step, anddrying and preheating temperature is coated with paint curing temperature ± 20 °C. This process not only can improve the galvanized pipe painted efficiency 30 times, and improve the quality of the galvanized pipe.

The device is known in the art equipment on the basis of the preheating furnace has dried before dipping trough. Technology and equipment of the present invention can not only large quantities of continuous galvanized pipe painted production, and ensure that the paint quality, the surface can not afford to bubble, can not afford the orange peel, ergonomics can improve two or three times, so make look more beautiful!

Galvanized coating on pipe surface

Galvanized coating has a number of characteristics that make it a well-suited corrosion protective coating for iron and steel products in most environments.

Th excellent field performance of Galvanized coating results from its ability to form dense, adherent corrosion product films of corrosion considerably below that of ferrous materials (some 10 to 100 times slower depending upon the environment). While a fresh zinc surface is quite reactive when exposed to the atmosphere, a thin film of corrosion products develops rapidly, greatly reducing the rate of further corrosion. In addition to creating a barrier between steel and the environment, zinc also has the ability to cathodically protect the base metal. Zinc, which is anodic to iron and steel, will preferentially corrode and protect the iron or steel against rusting when the coating is damaged.

Many different types of zinc and each has unique characteristics. These characteristics not only affect applicability but also the relative economics and expected service life.The method of processing, adhesion to the base metal, protection aff orded at corners, edges, and threads, hardness, coating density, and thickness can vary greatly among the diff erent coatings.This is practical aid discusses each of the major types of zinc coatings, applied by batch hot-dip galvanizing, continuous sheet galvanizing,electro galvanizing, zinc plating, mechanical plating, zinc spraying, and zinc painting, to help specialists assess and select zinc coatings for corrosion protection.

After deciding to use a Galvanized coating for corrosion protection, some factors must be considered to ensure the proper coating is selected for the intended application and service environment. Obviously, zinc coating processes which are limited to small parts, and operations limited to continuous lines in steel mills (i.e. continuous galvanizing and electrogalvanizing) cannot be considered for the protective coating of structural steel members. Each Galvanized coating reviewed provides various degrees of corrosion protection. When selecting a coating, it is important to investigate the corrosiveness of the exposure environment to ensure the Galvanized coating selected will provide adequate service life for the cost.

Galvanized pipe corrosion principle

Galvanized steel pipe is is state of molten metal zinc and iron substrate reaction of alloy layer, so that the substrate and the coating combination of both.

Galvanized pipe corrosion principle - Galvanized Steel Pipe Vs black steel pipe

On the use of technology in galvanizedHot dip galvanized firstly do the pickling, in order to remove the steel surface of iron oxide, after pickling, through an aqueous solution of ammonium chloride or zinc chloride or ammonium chloride and chlorinated zinc mixed aqueous solution tank for cleaning, and then into hot-dip plating bath. Hot-dip galvanized with coating uniformity, strong adhesion, long life and other advantages. Therefore, techniques by hot dip galvanized steel substrate and the molten bath through complex physical, chemical reaction, the formation of a corrosion-resistant zinc-alloy layer of compact structure. Therefore, galvanized steel alloy layer and layer of pure zinc, steel base blend make the corrosion resistance ability.

Zinc chemical lively sex is higher than iron, when electrochemical corrosion occurs, the first corrosion is zinc instead of iron, zinc oxide and relatively compact, which can prevent further oxidation. Usually galvanized steel has good corrosion resistance, corrosion of buried metal pipes is divided into two kinds of uniform corrosion and localized corrosion, localized corrosion mostly dominated, the danger is the greatest. Steel corrosion in soil electrochemical dissolution process is mainly due to the formation of corrosion cells resulting pipeline corrosion perforation. Press the corrosion cell anode and cathode spacing size, but also shape the steel into micro-cell corrosion corrosion and macro cell corrosion two categories.

Electrochemical corrosion for buried pipeline process, steel corrosion inhibition method from which to start a process. If the pipe wall plus anti-corrosion coating, loop resistance can be increased, reducing the corrosion current; external DC power supply, so that the soil pipe causing negative potential, the formation of cathodic protection anode potential difference can be eliminated from the root to stop the process of anode and cathode proceed. But once the anti-corrosion coating is damaged, exposed iron parts will accelerate localized corrosion. Therefore, anti-corrosion coating and cathodic protection combined rid of this method is the table, economical and effective.

Galvanized steel hardness

Galvanized steel in terms of hardness test is a Brinell hardness, Rockwell hardness, Vickers hardness, Shore hardness, micro-hardness and high-temperature hardness, etc.,

which can be divided into a variety, most of the manufacturers or using a Buchner,Rockwell, Vickers hardness of these three methods.

Brinell hardness measurement principle is the test force F (N) with a certain size, the diameter D (mm) of hardened steel balls or carbide ball pressed into the surface of the metal under test, to maintain a predetermined time after the drop test force, the the indentation average diameter d (mm) measured with a reading microscope, and then the equation Brinell hardness HB value, or the value d from the prepared Brinell hardness table to detect HB Brinell hardness measurement method is suitable for cast iron, non-alloy, annealing and quenching and tempering steel, the determination should not be too hard, too small, too thin and the surface does not allow the larger indentation specimen or workpiece.

Rockwell hardness test when the sample is too small or Brinell hardness (HB) is greater than 450, to switch to a Rockwell hardness measurement. The test method is an apex angle of 120 degrees with a diamond cone or the diameter 1.59mm/3.18mm the ball, pressed into the surface of the material under a certain load, the hardness of the material by the indentation depth obtained.

The Vickers hardness means a standard of the hardness of the material. Vickers hardness there is a small negative Vickers hardness test load 1.961 <49.03N, it applies to a thinner workpiece, the tool surface or coating hardness measurement; micro-Vickers hardness test load <1.961N applicable to the metal foil, , of the ultra-thin surface layer hardness measurement.

Galvanized steel pipe welding technology

Galvanized steel welding characteristics:
Galvanized steel is generally in the low-carbon steel outer layer of zinc-plated, galvanized layer is generally in the 20um thick. Melting point of zinc in 419 °C, bp 908 °C or so. In welding, the zinc melted into the liquid floating on the surface or in the root of the weld pool position. Zinc has a greater degree of solid solution of iron, zinc, liquid etching along the grain boundary deep weld metal, low melting point of zinc to form a “liquid metal embrittlement.” Meanwhile, zinc and iron can form brittle intermetallic compound phase of the weld metal of these brittle plastic reduction in the tensile stress and cracks. If the welding fillet welds, especially T-joint fillet most prone to penetrate the cracks. When welding galvanized steel, bevel edge surface and a zinc layer under the action of the arc heat, oxidation, melting, evaporation and even volatile white smoke and steam, can easily cause weld porosity. Due to oxidation and the formation of ZnO, the high melting point of about 1800 °C or more, if the welding process parameter is too small, will cause slag ZnO, simultaneously. Since Zn as a deoxidizer. Produce FeO-MnO or FeO-MnO-SiO2 slag melting oxides. Second, because the evaporation of zinc, a large amount of white smoke evaporation, stimulate the human body, harmful effects, therefore, necessary to weld galvanized layer of polishing off. 
Galvanized welding process control 
Galvanized steel welding preparation and the general low-carbon steel is the same, you need to pay attention is to seriously handle groove size and the nearby zinc coating. To weld penetration, beveling size should be appropriate, generally 60 ~ 65 °, to leave a certain gap, is generally 1.5 ~ 2.5mm; zinc in order to reduce the penetration of the weld, the weld before, the groove may be galvanized layer clear later welding. In actual supervision, using a centralized hit groove, leaving a blunt edge technology for centralized control, two welding process, reducing the possibility of lack of penetration. Welding galvanized steel pipe should be based on a matrix material selection, general ease of low carbon steel due consideration, the choice of J422 is more common. 
Welding techniques: the first layer of multi-layer welding weld seam, try to make it melt the zinc layer vaporization, evaporation and escape the weld, which can greatly reduce the liquid zinc remain in the weld. In fillet welding, the same as in the first layer and make the molten zinc vaporization, evaporation and escape the weld, which is shifted forward end portion of the first electrode of about about 5 ~ 7mm, when the zinc layer melted and then continue to move back to its original position welding. Horizontal and vertical welding again, if use short-slag welding, such as J427, tend to be small undercut; roundtrip transportation if the front and rear of technology, but also can be non-defective weld quality.

Galvanized steel clamp connection technology applications

Galvanized pipe is protected by zinc, so it is not easy to rust, galvanized steel pipe is lighter than seamless steel pipe, if it is used in the balcony, the best light with galvanized pipe, because seamless steel pipe is heavy with thick wall thickness, and the cost of seamless steel pipe is higher than galvanized steel pipe, as well as galvanized steel is durable, useful life is much more than a seamless pipe. If the quality is excellent, using twenty years should not be an issue. Surface coated or hot dip galvanized welded steel pipe can enhance corrosion resistance and prolong life.

Pipe clamp - Galvanized Steel Pipe Vs black steel pipe

Galvanized steel pipe with corrosion-resistant, not easy to pollution the transmission medium, which is widely used in domestic water supply systems, fire water systems, heating systems and gas delivery systems. In order to ensure the transmission medium process requirements and corrosion requirements, galvanized steel connection technology, the most widely used method is threaded connection. Clamp connection method for large diameter pipe connected to the system with easy maintenance construction, fast, able to meet higher working pressure requirements for piping systems, piping installation of high quality, low requirements of the construction team, the small number of requirements, equipment and simple, the disadvantage is the cost of using a clamp connection fittings slight increase.

Galvanized pipe for water - Galvanized Steel Pipe Vs black steel pipe

Threaded connection clamp connection technology and process shortcomings compare

1, during installation in pipe, a higher quality threaded threaded connection requirements, is more difficult threaded processing. After more than DN50 galvanized steel pipe specifications, especially for DN100, DN125, DN150 and other large-sized pipes, even to have the construction experience, high-level team of construction, installation and construction are more difficult, and this clamp connection method can overcome these difficult because only a pipe clamp connection butt, butt clamps, tighten the nut.

2, threaded connections, requiring high pressure piping systems is difficult to meet the requirements. In practice, for the operating pressure exceeds 1MPa piping system, using threaded connection, it is difficult to ensure that no leakage, but with clamp connection method can meet the installation requirements are relatively higher operating pressure piping systems.

3, threaded process connection pressure test of the entire system installed, or use, pipeline leak occurred after maintenance more difficult. Either a large area removal, replacement pipe fittings, pipes, or cut off the pipeline, with the welding tool repair. The former because a lot of demolished normal channels, thus greatly increasing the amount of maintenance work, while the latter uses a construction maintenance method specification is not allowed because of galvanized steel by welding, heat destroys the galvanized layer, so that the pipe joints at the long-term use may affect water quality, and even leaking, especially the fire sprinkler system. And for such shortcomings, clamp connection technology embodies a greater advantage. Such as certain pipe or a pipe leakage, simply connect the pipes, fittings at both ends of the clamp nut open, you can replace, very convenient, can greatly reduce installation engineering rework engineering, but also normal use can reduce the amount of maintenance work.

4, threaded pipe connections requiring high quality, especially for higher working pressure fire pipeline system, does not allow the tube trachoma, burrs and other defects threaded tolerance with the bad, but in the actual installation works, often due to pipe fittings amount of maintenance and rework caused by unqualified installation is very large, such as the use of this clamp connection technology, the entire piping system can significantly improve the quality of the installation.

5, install the necessary equipment and tools, threaded connection requires large-sized pipe wrench, chain wrench and twist wire machine, but you only need to pipe clamp connection technology equipment and general machining grooves end wrench to operate, relatively speaking , is much simpler.

6, the construction team technical quality requirements, threaded connection when applied to large diameter, high pressure piping systems, high technical level of construction workers, construction experience demands to meet the higher number, but with clamp connection technology, for the number of technical quality requirements of the construction workers are much lower, requiring less fit.

7, using a clamp connection pipe threaded connection time investment than the slightly more than the threaded connection clamp connection because in addition to the normal pipe clamps more than a cost, but reduces rework maintenance costs, so the total project cost to said little effect.

Advantage of galvanized spiral pipe welding process

Galvanized pipe welding processes can be divided into spiral welded and straight seam welded, and galvanized spiral welding process is relatively wider number of applications, but also more complex.

Galvanized spiral pipe welding method is first out of the forward end portion of the electrode about 5 ~ 7mm, without leaving a blunt edge technology for centralized control to ease the industry needs to pay attention to seriously handle groove dimensions and near-plated zinc layer.

For penetration, undercut the tendency will be very small, If the front and rear of the round-trip transportation technology is used, generally 1.5 ~ 2.5mm; to reduce zinc weld penetration, with a focus on playing groove industry downturn, such as the use of short welding slag such as J427, to leave some space sector is expected to greatly reduce the liquid zinc remain in the weld, when welding fillet welds, you can get no defects of welding quality.

Advantages of galvanized spriral welding: the welding precision can not be compared for the straight seam welding, large diameter pipes or some special pipes are all used the spiral welded pipe, because spiral welding welding density is big, welding up is very flexible, welded together can form a variety of changes.

But straight seam welding can only weld one line, the curve of straight seam welding completely couldn’t play the advantages, therefore, The use of spiral welded is the best choice.

Disadvantages of Galvanized Steel pipe

Galvanized steel is all around, even when not visible. Many houses built before the 1960s are framed with it, and many buildings still use piping made from galvanized steel.

This type of metal is inexpensive, durable, and resistant to corrosion, which makes it attractive to the construction industry. Plus, it can be reused and recycled, which makes it ideal for green projects. However, there are many disadvantages to using galvanized steel, and it is therefore gradually being replaced in most plumbing systems.


Significance
Galvanized steel is used primarily in the construction industry, and its primary applications include roofing, support beams and braces for walls, and piping. This type of metal, often used for heating and cooling duct work, safety barriers and handrails, is an essential material in automotive body parts. The reasons for its popularity include its strength and resistance to corrosion, which are both due to the protective layer of zinc added to the steel during the galvanization process. Galvanized steel is unmatched in popularity for marine applications, as other materials are prone to rusting and therefore deteriorate rapidly.

Features
Galvanized steel is steel that has been coated with zinc to prevent corrosion. The steel is submerged in hot, melted zinc, which triggers a chemical reaction that permanently bonds the zinc and steel together. During the galvanization process, the steel is first exposed to zinc at a temperature of approximately 860 degrees. The zinc reacts to available oxygen in the environment to form zinc oxide, which then forms zinc carbonate after reacting to carbon dioxide. Iron molecules in the steel react with the zinc, creating layers of metal that are able to withstand even long term contact with saltwater.

Benefits
Because galvanized steel is coated with zinc, it offers many benefits over traditional steel or iron piping. The zinc coating drastically reduces corrosion and prevents minerals from depositing inside the pipe lines. In larger construction projects, such as sewer systems and farm irrigation, galvanized steel pipes are often the piping of choice and often remain in working order with little maintenance for 40 years or more. Galvanized steel is more flame resistant than PVC piping, and is stronger than aluminum piping. This type of metal also works well under freezing conditions.

Disadvantages
In spite of its many benefits, galvanized steel is not always the ideal choice. When mixed with yellow brass, galvanized steel triggers dezincification, and it results in electrolytic action when combined with nonferrous metals, such as copper and brass. Galvanized steel should never be used underground unless properly covered, which can be inconvenient for many jobs, and it often hides significant defects beneath the zinc coating on the steel. Galvanized steel pipes may contain lead, which corrodes quickly and reduces the lifespan of the piping. Moreover, galvanized steel may leave rough patches inside pipes, resulting in serious failures and stoppages that can be expensive to repair. Because of these issues, most modern homes use copper piping as an alternative.

Warning
Galvanized steel and copper cannot be connected to each other as the two can produce a chemical reaction that weakens the joint. Because of this, it is crucial to use only one type of material in a system, especially for plumbing repairs. In older homes, galvanized steel also poses a risk due to its lead content, which has been proven to be unsafe for both children and adults. High levels of lead in drinking water has been linked to decreased intelligent, behavior problems, and neurological conditions in children. If you suspect your family is at risk of lead poisoning caused by galvanized pipes, have your water tested to determine the levels of lead present, and get your children evaluated by a pediatrician as soon as possible. The World Health Organization states that all owners of homes built prior to 1970 are at risk and recommends having their water tested. The WHO also recommends that anyone living in an older home flush their taps by running cold water through their pipes each morning before drinking or cooking.

Usage characteristics of thin-walled galvanized stainless steel tube

In building water distribution system, galvanized steel pipe has been over a hundred years glorious history and a variety of new plastic pipes and composite pipes have developed rapidly, but there are some deficiencies due to varying degrees, far from being able to fully meet the water supply pipe needs of the department and the state of drinking water and water quality requirements. Therefore, the experts predicted: the building water supply pipe will eventually be restored to the era of metal pipe. according to the application of foreign experience, wall stainless steel pipe for pipe is one of the best overall performance.

Domestic thin-walled 316 stainless steel tubes that promote the use of the time is ripe:
First, thin-walled stainless steel tube, the country began production in the late 1990s, the use of today’s pipe-and-coming in the field of newborn family have been widely used in building water supply and drinking water pipeline.

Second, the thin-walled stainless steel tube durable has been recognized by the engineering community, and the parties concerned are to reduce the wall thickness, reducing the price to proceed in order to facilitate further promotion. Especially small diameter stainless steel pipe, the price is not high, supporting the connection method, the pipe reliability and price are the main factors that determine its development. Domestic has been a developer in Sichuan, Guangdong, Zhejiang, Jiangsu and other places independently developed connection technology and pipe fittings, pipe promising.

With the implementation of China’s reform and opening-up policy, the national economy experienced rapid growth, urban housing, public buildings and tourist facilities to build a large number of new requirements on the hot water supply and domestic water supply. Water quality problems, there is growing attention, and are required to improve. Galvanized steel pipe is commonly used pipe because of its easy to corrosion under the influence of the relevant national policies, will gradually exit the stage of history, plastic pipe, composite pipe and copper pipe became the piping system used pipe.

However, in many cases, the stainless steel tube is more advantages, especially the wall thickness of only 0.6 ~ 1.2mm wall stainless steel pipe in high-quality drinking water systems, hot water system and will give top priority to safety, health water supply system, with safe, reliable, environmental health, economic application. Engineering practice at home and abroad has been proven to be one of the best overall performance of water supply system, a new, energy-saving and environment-friendly pipe water supply pipe is also a very competitive, improve water quality, improve people’s living standard will play no comparable to the role.

Coat-Plating Methods of Galvanized steel Pipes
Hot dip galvanizing can protect steel pipes very well. When zinc is in liquid state, plate the steel with a thick layer of pure zinc after the complicated physical and chemical interaction and thus will make the hot dip galvanizing come into being. Also a zinc and steel alloy layer will be generated during this process. With this kind of layer and corrosion resistance feature, galvanized pipes can be applied to different severe corrosion environments, such as strong acid, alkali frog, etc., which is incomparable to other electro galvanizing.
Advantages of hot dip zinc galvanized pipes:
First, in general atmosphere, a very thin and dense layer of zinc oxide will be formed on the surface of zinc coating. It is hard to dissolve in water, therefore plays a certain protective effect to steel substrate. So, if the surface of steel pipe is covered with a quite thick and dense pure zinc layer, the steel substrate will be protected from contacting with any corrosive solution and avoid erosion.
Second, galvanized connection is very strong. When dissolving zinc and iron together, a good wear resistance will come into being and it can help the steel pipe become more strong and durable.
Third, after hot dip galvanizing, the mechanical properties of steel pipes will be improved effectively. Also, it can eliminate the stress of steel pipes in molding and welding process and benefit the lathe work.
Forth, due to the excellent ductility of zinc, its alloy layer can combine strongly with steel pipe so that plating will be protected from damage even in rolling, bending, wiredrawing, cold blanking and other molding situations.
What’s more, the surface of galvanized pipe will become bright and beautiful after the hot dip galvanizing.
Galvanized Steel Pipe Pickling
The main reasons for the pickling of steel pipe:
(1) when the steel pipe in the feed to be strictly checked, to do not put into acid pickling unqualified steel pipe. .
(2) steel pipe in the vibration is not careful operation.
(3) pickling time and lack of hydrochloric acid content.
The main reasons for the steel pipe over pickling:
(1) hydrochloric acid content is too high.
(2) pickling time is too long.
After pickling the outer surface of steel pipe is smooth, with or without residual iron oxide, with or without grease pollution of steel pipe surface.
Galvanized Steel Pipe Washing
1) steel pipe washing in the flow of water tank, the water should be all immersed in water, pickling straps to relax, ups and downs three to four times.
2) After washing, the pipe should be water control net as soon as possible solvent treatment to prevent the oxidation of steel.
3) cleaning water iron salt content standards may not exceed the standard, no other debris, keep clean and transparent.
4) in the washing tube, the operator is strictly prohibited across the pickling tank to prevent slipping or fall into the acid tank wounding.
Galvanized Steel Pipe Solvent Treatment
1, the steel pipe into the solvent tank, the tape to relax all the steel immersed in the solvent, does not allow the steel pipe surface exposed solvent surface. Such as steel pipe at both ends do not take bubbles so far, and then lifting the side of the pipe vibration up, lifting the steel pipe control solvent into the drying rack.
2, steel pipe in the solvent treatment process, the tilt angle of steel pipe is not greater than 15 °.
3, the pipe immersed in the solvent time of 60 to 120 seconds, on duty back to the tube soak 3 to 5 minutes, successor to the plating tube soak 5 to 10 minutes.
4, solvent temperature: keep the solvent clean at room temperature.
5, the solvent-treated steel pipe, do not stick to other dirt, do not pour Sheung Shui, placed in the drying platform balance; placed on the drying bench steel pipe, pipe is not allowed to go to the top, such as must be up , The feet must be coated with ammonium chloride and then to the tube to work.
Galvanized Steel Pipe Passivation
Meaning: When the parts require a longer period of storage and transportation, the deal between the passivation treatment to prevent corrosion during storage and transportation process. The corrosion products are often referred to as white rust. Common passivation methods are chromate and phosphate method.
1, passivation method using hot dip galvanized pipe directly above the runway spray passivation solution, sprayed in the distance from the location of one meter by the steam knife to wipe the net with the liquid, pay attention must be blown net.
2, the use of compressed air wipe, blow off the surface of the steel pipe with the liquid and make the coating uniform. By adjusting the pressure to adjust the thickness of the coating, must not have excess liquid beads attached to the surface of the zinc tube.
Differences between Water Gas Pipeline and Galvanized Steel Pipe
The biggest difference between water gas pipeline and galvanized steel pipe is that the former is seamed steel pipe and its pressure bearing capacity is low, the later is seamless steel pipe and its pressure bearing capacity is high.
Water gas pipes are constituted by welded steel pipes with thick wall, its materials are different from galvanized steel pipes. Water gas pipe is made of low-carbon steel welded pipe. those Galvanized are called galvanized iron tubes. Those non-galvanized are called black pipes.
Galvanized steel pipe is divided into cold galvanized steel pipe and hot galvanized steel pipe. The electroplating of hot galvanized steel pipe is relatively strong, its zinc layer is thick, and there is a blue ring logo on the head of galvanized pipe. Cold galvanized steel pipe is also made by electroplating, but it is made with less technology, and its performance is far worse, no blue logo. Cold galvanized steel pipe has been banned, hot galvanized steel pipe is promoted temporary use by country.
Now the water gas pipelines used in the project are basically galvanized pipe, instrument air galvanized steel pipe and galvanized steel pipe of cable laying is using hot galvanized galvanized steel pipe to produce, since the hot galvanized pipe is more corrosion-resistant. The electrical piping on the project is thin-walled tube, it can not be under pressure.

Difference between galvanized pipe and seamless pipe

Galvanized pipe is protected by zinc, so it is not easy to rust, galvanized steel pipe is lighter than seamless steel pipe, if it is used in the balcony, the best light with galvanized pipe, because seamless steel pipe is heavy with thick wall thickness, and the cost of seamless steel pipe is higher than galvanized steel pipe, as well as galvanized steel is durable, useful life is much more than a seamless pipe. If the quality is excellent, using twenty years should not be an issue.

Surface coated or hot dip galvanized welded steel pipe can enhance corrosion resistance and prolong life.

Manufacturing process difference: galvanized steel refer to a galvanized surface, there may be welded pipe, it could be seamless, seamless steel pipe manufacturing process means welded and seamless points.

Seamless pipes are extensively applied for the nuclear device, gas, petrochemical, ship building and boiler industries. seamless pipes dominates 65% of market share in Chinese boiler industry.

Uses difference:

Seamless steel pipe is very widely used, except for water, gas, oil, general low pressure fluid line pipe, also used as heating oil oil industry in particular, marine oil field oil well pipes, pipelines, chemical coking equipment, a condensate cooler, coal distillation of wash oil exchange Used pipe, and trestle piles, mine tunnel support frame with a pipe. Galvanized pipe generally is utilized to make make fences, fence, fence, balcony guardrail. Commonly used in municipal projects, roads, factories, schools, development zones, gardens, squares, residential and other places.

What is a Black Steel Pipe?

Black steel pipe is a non-galvanized steel pipe. Black steel pipe is used in applications that do not require the pipe to be galvanized. This non galvanized black steel pipe acquired its name because of its dark coloured iron oxide coating on its surface. Because of the strength of black steel pipe it is used for transporting gas and water to rural areas and for conduits that protect electrical wiring and deliver high pressure steam and air. The oil field industry also uses black pipes for piping large quantities of oil through remote areas.

Black steel pipes and tubes can be cut and threaded to fit your project. Fittings for this type of pipe are of black malleable (soft) cast iron. They connected by screwing onto the threaded pipe, after applying a small amount of pipe joint compound on the threads. Larger diameter pipe is welded on rather than threaded. Black steel pipe is cut either with a heavy-duty tube cutter, cut-off saw or by a hacksaw. You can also get Mild Steel ERW Black Pipes that are extensively used for gas distribution inside & outside of the home, and for hot water circulation in boiler systems. Can also be used in usage in potable water or drains waste or vent lines. Please browse our construction pipe and tube directory for a supplier to meet your needs.

History of black steel pipe

William Murdock made the breakthrough leading to the modern process of pipe welding. In 1815 he invented a coal burning lamp system and wanted to make it available to all of London. Using barrels from discarded muskets he formed a continuous pipe delivering the coal gas to the lamps. In 1824 James Russell patented a method for making metal tubes that was fast and inexpensive. He joined the ends of flat iron pieces together to make a tube then welded the joints with heat. In 1825 Comelius Whitehouse developed the “butt-weld” process, the basis for modern pipe making.

Developments of black steel pipe

Whitehouse’s method was improved upon in 1911 by John Moon. His technique allowed manufacturers to create continuous streams of pipe. He built machinery that employed his technique and many manufacturing plants adopted it. Then the need arose for seamless metal pipes. Seamless pipe was initially formed by drilling a hole through the center of a cylinder. However, it was difficult to drill holes with the precision needed to ensure uniformity in wall thickness. An 1888 improvement allowed for greater efficiency by casting the billet around a fire-proof brick core. After cooling, the brick was removed, leaving a hole in the middle.

Applications of black steel pipe

Black steel pipe’s strength makes it ideal for transporting water and gas in rural and urban areas and for conduits that protect electrical wiring and for delivering high pressure steam and air. The oil and petroleum industries use black steel pipe for moving large quantities of oil through remote areas. This is beneficial, since black steel pipe requires very little maintenance. Other uses for black steel pipes include gas distribution inside and outside homes, water wells and sewage systems. Black steel pipes are never used for transporting potable water.

Modern Techniques of black steel pipe

Scientific advancement has greatly improved on the butt-weld method of pipe making invented by Whitehouse. His technique is still the primary method used in making pipes, but modern manufacturing equipment that can produce extremely high temperatures and pressure has made pipe making far more efficient. Depending upon its diameter, some processes can produce welded seam pipe at the incredible rate of 1,100 feet per minute. Along with this tremendous increase in the rate of production of steel pipes came improvements in the quality of the final product.

Quality Control of black steel pipe

The development of modern manufacturing equipment and inventions in electronics allowed for marked increases in efficiency and quality control. Modern manufacturers employ special X-ray gauges to ensure uniformity in wall thickness. The strength of the pipe is tested with a machine that fills the pipe with water under high pressure to make sure the pipe holds. Pipes that fail are scrapped.

Difference between black steel pipe and galvanized steel pipe

ASTM A500 Black Steel Pipe - Galvanized Steel Pipe Vs black steel pipe
ASTM A500 Black steel pipe

Black steel pipe is the uncoated steel and is also called as black steel.

The dark color comes from the iron-oxide formed on its surface during manufacturing. When steel pipe is forged, a black oxide scale forms on its surface to give it the finish which is seen on this type of pipe. 

Galvanized steel pipe is that steel that has been covered with a layer of zinc metal. During galvanizing, steel is immersed in a molten zinc bath, ensuring a tough, uniform barrier coating. Galvanized pipe is covered with a zinc material to make the steel pipe more resistant to corrosion. 

The brief of difference

  • Both the black pipe as well as galvanized pipe is made of steel.
  • While galvanized pipe has a zinc coating, black pipe does not have it
  • Because it corrodes easily, black pipe is more suitable for carrying gas. On the other hand, galvanized pipe is ideal for carrying water but not suitable for carrying gas
  • Galvanized pipe is more expensive because of zinc coating
  • Galvanized pipe is more durable

Difference in appearance

The primary purpose of black steel pipe is to carry propane or natural gas into residential homes and commercial buildings. The pipe is manufactured without a seam, making it a better pipe to carry gas. The black steel pipe is also used for fire sprinkler systems because it is more fire-resistant than galvanized pipe. The primary use of galvanized pipe is to carry water to homes and commercial buildings. The zinc also prevents the buildup of mineral deposits that can clog the water line. Galvanized pipe is commonly used as scaffolding frames because of its resistance to corrosion.

Difference in problems

The zinc on galvanized pipe flakes off over time, clogging the pipe. The flaking can cause the pipe to burst. Utilizing galvanized pipe to carry gas can create a hazard. Black steel pipe, on the other hand, corrodes more easily than galvanized pipe and allows minerals from water to build up inside it.

Difference in Cost

Galvanized steel pipe costs more than black steel pipe because of the zinc coating and manufacturing process involved in producing galvanized pipe. Galvanized fittings also cost more than the fittings used on black steel. Galvanized steel pipe must never be joined with black steel pipe during the construction of a residential home or commercial building.

Difference between plastic coated pipe and galvanized steel pipe

Galvanized coating has a number of characteristics that make it a well-suited corrosion protective coating for iron and steel products in most environments.

Th excellent field performance of Galvanized coating results from its ability to form dense, adherent corrosion product films of corrosion considerably below that of ferrous materials (some 10 to 100 times slower depending upon the environment). While a fresh zinc surface is quite reactive when exposed to the atmosphere, a thin film of corrosion products develops rapidly, greatly reducing the rate of further corrosion. In addition to creating a barrier between steel and the environment, zinc also has the ability to cathodically protect the base metal. Zinc, which is anodic to iron and steel, will preferentially corrode and protect the iron or steel against rusting when the coating is damaged.

Many different types of zinc and each has unique characteristics. These characteristics not only affect applicability but also the relative economics and expected service life.The method of processing, adhesion to the base metal, protection aff orded at corners, edges, and threads, hardness, coating density, and thickness can vary greatly among the diff erent coatings.This is practical aid discusses each of the major types of zinc coatings, applied by batch hot-dip galvanizing, continuous sheet galvanizing,electro galvanizing, zinc plating, mechanical plating, zinc spraying, and zinc painting, to help specialists assess and select zinc coatings for corrosion protection.

After deciding to use a Galvanized coating for corrosion protection, some factors must be considered to ensure the proper coating is selected for the intended application and service environment. Obviously, zinc coating processes which are limited to small parts, and operations limited to continuous lines in steel mills (i.e. continuous galvanizing and electrogalvanizing) cannot be considered for the protective coating of structural steel members. Each Galvanized coating reviewed provides various degrees of corrosion protection.

When selecting a coating, it is important to investigate the corrosiveness of the exposure environment to ensure the Galvanized coating selected will provide adequate service life for the cost.

How to Distinguish Black Steel Pipe and Galvanized Steel Pipe?
Black steel pipe and galvanized steel pipe have several respects similar to each other, such as they are common kind of pipe applied to transport liquid and gas, so there are many people can’t distinguish them clearly.
The main difference between black steel pipe and galvanized steel pipe:
Black steel pipe and galvanized pipe all use steel as raw material. And general speaking, galvanized steel pipe is more expensive and more durable since galvanized pipe has a zinc coating while black pipe does not. Galvanized pipe covered with a layer of zinc which makes it have higher ability of corrosion protection and help to prevent the accumulation of mineral deposits that will block the pipe.This will lead to a burst. So galvanized steel pipe is more suitable for carrying water instead of gas.
For transportation, galvanized pipe is mainly used for carrying water to supply home and commercial buildings. It is also serve as scaffolding frames because of its rust prevention. Black steel pipe is manufactured as seamless which makes it a better type for gas transportation. It can be used for fire sprinkler system since it can prevent fire better than galvanized pipe. Since it has a dark color surface that is form by iron oxide during the manufacturing process, it is called black steel pipe. The main difference between steel pipe and galvanized pipe lies in the surface. Black steel pipe is uncoated and made without steam, and therefore, it is widely used for transporting gas like propane and natural gas to residential and commercial building. Black steel pipe is more easily to corrosion than galvanized pipe, so it is more suitable for transporting gas. black steel pipe is not suitable for water transport. Black steel pipes are tending to corrode in water and mineral of the pipe will dissolve into the water and clog the line as well.
How to differentiate this two pipe? Prime Steel Pipe shows you three ways:
1. Examine the color of the pipe. Black steel pipe is flat black and galvanized pipe is silver and gray. Black steel pipe is darker than galvanized pipe. 
2. Tell the difference by the material they carry. galvanized pipe is usually applied for water carriage, black steel pipe for gas deliver.
3. Tell from the year the pipe being used. If the pipe is installed after 1950s, it’s likely to be black steel since black steel pipe used later than galvanized pipe.

Source: China Steel Pipe Manufacturer – Yaang Pipe Industry Co., Limited (www.steeljrv.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

If you want to have more information about the article or you want to share your opinion with us, contact us at sales@steeljrv.com

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  • How to get high quality flanges

  • How to get high quality alloy steel pipes

  • How to get high quality pipe fittings

  • How to get high quality heat exchanger tubes

  • The difference between steel tubes and steel pipes

  • THE DIFFERENCE BETWEEN STEEL TUBES AND STEEL PIPES

  • Difference between welded steel pipe and seamless steel pipe

  • Characteristics of seamless steel pipes

  • Low, Medium and High Pressure Boiler Pipe

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Reference:

  • https://www.yaang.com

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