Internal coating pipes

Internal coating pipes

Using epoxy powder coating is for 30 years of history in a foreign country due to the wide range of sources of raw materials.

Internal pipe coating is the process of spraying an epoxy material to the pipe's interior using Picote technology. The main differences between internal pipe coating and replacing your pipes are cost and project scope. The cost of coating your pipes is less than the cost of replacing them.


Using epoxy powder coating is for 30 years of history in a foreign country due to the wide range of sources of raw materials, production methods are simple, cheap, good performance, which do not pollute the environment and long service life, so far it is a good anti-corrosion coatings.

Internal and external 2 and 3- layer coating is applied for oil and gas pipelines, product pipelines and fire extinguishing systems

Use of pipes with internal coating provides an ecological safety, a reliability, keeps the good quality of drinking water in pipeline systems during the long term operation.

Petroleum Institute of Construction Technology in China for the oil field pipeline corrosion problems and successfully develop the anti-corrosion coating of epoxy powder to fill the blank of the domestic pipeline anti-corrosion powder coating.

The paint coating has excellent chemical resistance, good mechanical properties, high electrical insulation properties and good toughness. Corrosion tests predict coating life, the conditions intact Chu apply the paint to do the inner coating of oil, gas and water pipes, the life expectancy of up to l5 years; do sewage and mixed water injection pipeline within the coating, life up to 5 to 7 years. The construction method using the pipeline industry, the most widely used static thermal spraying method. According to the data reported, due to the transmission medium, the thickness of the coating of epoxy powder coating requirements are also different. Domestic oil, gas, water and sewage, etc. containing certain corrosive media, anti-corrosion pipe is the best thick coating. Electrostatic heat till coated thick coating, spraying a coating thickness of up to 250 ~ 350/an maximum thickness of up to 500, ~ 'n. Electrostatic Powder the moraine coated is a surface treatment of the solid powder, it has a simple, easy to operate equipment, process, free from the workpiece size limit.

Inner surface heat-resistant paints and coatings

The technology is the surface heat-resistant paint coating that mixed epoxy resin main agent and epoxy resin curing agent in the steel pipe (each about 5.5m), natural drying a certain period of time, more than 6O ℃ warm water or 60 ℃ or more hot air into the tube, forced drying, more than three hours to complete the steel pipe coating. The technology is mainly applied to water pipelines and transmission and hot water pipe internal coated first surface treatment on the pipe wall, and then use the compressor by the pressure of air or nitrogen, Pressure between the resistance and the two applicator thermal coating in the pipe wall to form a uniform coating. Coating must 6O ° C more than warm water or 60 "C, hot air above the mandatory drying and natural drying is heat resistant to dissolution performance decreased significantly.

Epoxy resin latex cement mortar lining

Epoxy resin latex cement mortar lining in the steel tube surface first coated with epoxy cement water-based paint, to form the undercoat, and then based on this coating the lining. The use of materials is containing epoxy resin latex cement mortar. Colloidal silicon dioxide is added in the cement mortar. Cement water-based coatings and cement mortar contain ionic latex (a hydrocarbon solvent containing 5 to 8 sugars). The lining of steel pipes, except for sewage and water pipelines is also apply to oil, gas and steam pipelines. In order to get a solid lining, pipe lining before, the surface must be shot peening, shot peening is divided into dry and wet shot peening, if both methods are not adopted, can also be used to pickling.

Anti rust process

Some anti-corrosion methods include painting, covering, and electroplating.

Anti-corrosion steel pipe is processed through the preservation process, which can effectively prevent or slow down the process in the transport and use of chemical or electrochemical corrosion reaction of steel pipe.

Steel surface treatment is mainly anti rust, the following is anti rust process:

3-Layer Polyethylene Coating System

First step is to clean, use cleaning solvent emulsion cleaning the steel surface, in order to achieve the removal of oil, grease, dust, lubricants and similar organic matter, but it can not remove the steel surface rust, oxide, solder medicine.

Second step is to right tools rust, rust tools you want to have to use a wire brush, wire brush to remove loose or warped oxide, rust and slag. To achieve the desired effect of the rust, the hardness of the steel surface must be based on the original extent of corrosion and the required surface roughness, coating, etc. to select the type of abrasive, the epoxy layer, two or three layers polyethylene coating, using mixed abrasive grit and steel shot blasting easier to achieve the desired effect.

Third step is to do pickling, chemical and electrolytic pickling generally use two methods, using only chemical pickling pipeline corrosion. Although chemical cleaning can achieve a certain surface cleanliness and roughness, but there are some pollution to the environment.

Process Diagram of Three-Layer PE PP Coating

Process Diagram of Three-Layer PE PP Coating

Coating Specifications

Finally emphasis on the importance of surface treatment in the production, strictly control the process parameters when anti rust.

Process Diagram of Three-Layer PE PP Coating

The Importance of Anti-Corrosion Coatings for Carbon Steel Pipes

When it comes to transporting precious natural resources or other essential products, the integrity of the pipes used plays a pivotal role. Carbon steel pipes, widely utilized in various industries, are susceptible to corrosion over time. This is where anti-corrosion coatings step in as the frontline defense, ensuring the longevity and reliability of the pipes.

Anti-corrosion steel pipe is processed through the preservation process, which can effectively prevent or slow down the process in the transport and use of chemical or electrochemical corrosion reaction of steel pipe.

Coating Specifications

Anti-Corrosion Coatings

Anti-corrosion coatings serve as a protective shield against the relentless forces of corrosion that can compromise the structural integrity of carbon steel pipes. These coatings act as a robust barrier layer, strategically designed to inhibit or significantly slow down the formation of corrosion on the metal surface.

In the realm of carbon steel pipes, the battle against corrosion is ongoing. Anti-corrosion coatings emerge as the frontline warriors, safeguarding the structural integrity of pipes and ensuring that resources and products reach their destinations without compromise.

Pipe Coating Products

Fusion Bonded Epoxy – Fusion Bond Epoxy is a powder epoxy thermosetting coating applied for anticorrosion protection to steel pipelines. The pipe is first blast cleaned and heated. Then epoxy powder is spray applied by electrostatic guns to melt and form a uniform layer that hardens within a minute from application. Utilizing industry accepted materials supplied by manufacturers such as 3M, DuPont, and Valspar, the facility can apply FBE in a wide range of thickness to cost effectively meet any project specifications.

Fusion Bonded Epoxy with Abrasion Resistance Overcoating (FBE/ARO) – Utilizing two completely separate powder systems, the facility can produce FBE with an ARO at unprecedented processing speeds using industry accepted materials such as 3M 6352, DuPont 7-2610, and Lilly 2040.

Fusion Bonded Epoxy with High Temperature Resistant Overcoating – Utilizing two completely separate powder systems, the facility can produce FBE with a high operating temperature resistant overcoating such as DuPont’s Nap-Gard Gold and 3M’s 6258.

Fusion Bonded Epoxy with Zap-Wrap Overcoating – The facility is capable of processing line pipe with connections and of applying the Zap-Wrap abrasion resistance overcoating to the ends of each pipe.

Three Layer Polyethylene (3LPE)
To improve anticorrosion performance and adhesion, an additional layer of epoxy primer is sprayed onto pipe surfaces prior to the adhesive layer and Polyethylene top layer application. Three Layer Polyethylene is suitable for service temperatures from 60°C to 80°C (85°C peaks). Typical coating thickness is from 1-2 mm to 3-5 mm.

Three Layer Polypropylene (3LPP)
If a wider service temperature range and high stiffness is required, adhesive and top layers, applied over primer layer, are based on polypropylene instead of polyethylene. Three Layer Polypropylene is suitable for service temperatures up to 135 °C (140°C peaks). Typical coating thickness is from 1-2 mm to 3-5 mm.

Three Layer Polypropylene and Polyethylene
Three Layer applications involve a thermoplastic coating applied to steel pipelines as a form of anticorrosion protection. This mechanical resistance is appropriate when the risk of particularly severe coating damages exist. The Three Layer process involved several steps. First, the pipe surface is blast cleaned to remove any external residue from the mill or storage. It is then heated and sprayed with a Fusion Bond Epoxy (FBE) primer followed by the application of an adhesive copolymer and polyolefin polymers that are wrap extruded, one over the other.

Field applied products
3M: SK 134, SK6233, SK6352 Toughkote, SK 314, SK 323, SK 206N, SK 226N, SK 6251 DualKote SK-6171, SK 206P, SK226P,
3M Internal Coatings: Coupon EP2306HP
DuPont: 7-2500, 7-2501, 7-2502, 7-2508, 7-2514, 7-2803, 7-2504 Nap Gard Gold 7-2504, Nap Rock: 7-2610, 7-2617 FBE Powders
DuPont: Repair Kits; 7-1631, 7-1677, 7-1862, 7-1851
DuPont Internal Coatings: 7-0008, 7-0010, 7-0014, 7-0009SGR, 7-0009LGR, 7-2530, 7-2534, 7-2509
Akzo Nobel: FBE - Fusion Bond Epoxy
Internline 876 Seal Coat
Hampel: 85448,97840
Denso: 7200, 7900 High Service Temperature Coatings
Internal Liquid Epoxy: Powercrete Superflow

ERW pipe coating

ERW Pipe coating

Pipeline coating is the most consistent and successful solution for protecting ERW pipes from corrosion, from moisture, other harmful chemicals.

Therefore pipe anti-corrosion layer is an important barrier to prevent soil erosion. A well-known foreign scholar put forward" 3PE france protective layer", so far, anti-corrosion methods is widely used.

Coated pipes offer high resistance to corrosion on pipes and provide many benefits such as:

1. Increased Flow Capacity – A coating on pipes helps provide a smoother surface thus improving gas and liquid flow within pipes.

2. Reduced Cost – The pipeline coating increases the pipes durability so they can be deployed with minimum maintenance cost even in the harshest environments.

3. Lower energy usage – Various studies have shown that pipelines that are internally coated use less energy for pumping and compression of products through pipes. This helps in increased saving over time.

4. Clean delivery of products – The inhibitors used for the protection products can also be minimized by the use of coated pipes for delivery of products.

Thus, coating of pipelines can help you in reducing your maintenance cost and at the same time providing a corrosion free reliable protection.

Basic functions of erw pipe coating

  1. making the surface of ERW steel pipes free from electrochemical corrosion of the soil medium, the basic physics of bacterial corrosion protection.
  2. resisting the move of the soil medium creep stress, static stress and abrasion force method and structure of the basic machinery protection.

The basic principles of urban gas pipeline coating selection:


Measurement size

Measure weld stee pipes
Measure weld stee pipes
Measure weld stee pipes
Measure weld stee pipes
Flat oval pipes
Flat oval pipes


Packing weld stee pipes
Packing weld stee pipes
Packing weld stee pipes
Packing weld stee pipes
Packing weld stee pipes
Packing weld stee pipes
Packing weld stee pipes
Packing weld stee pipes
Packing weld stee pipes

Welded pipes specification and size


Product Name Executive Standard Dimension (mm) Steel Code / Steel Grade
Casting API 5CT Ø48.3~273 x WT2.77~11.43 J55, K55, N80, L80
Tubing API 5CT Ø48.3~273 x WT2.77~11.43 J55, K55, N80, L80, H40


Product Name Executive Standard Dimension (mm) Steel Code / Steel Grade
Line Pipes API 5L Ø60.3~273.1 x WT2.77~12.7 A25, A, B, X42, X46, X52, X56, X60, X65, X70, X80


Product Name Executive Standard Dimension (mm) Steel Code / Steel Grade
Electric-Resistance-Welded Steel Pipes ASTM A135 Ø42.2~114.3 x WT2.11~2.63 A
Electric-Resistance-Welded Carbon Steel and Carbon-Manganese Steel Boiler and Superheater Tubes ASTM A178 42.2-114.3 x 2.11-2.63 A, C, D
ERW and Hot-dip Galvanized Steel Pipes ASTM A53 Ø21.3~273 x WT2.11~12.7 A, B
Pipes for Piling Usage ASTM A252 Ø219.1~508 x WT3.6~12.7 Gr.2, Gr.3
Tubes for General Structural Purpose ASTM A500 Ø21.3~273 x WT2.11~12.7 Gr.2, Gr.3
Square Pipes for General Structural Purpose ASTM A500 25 x 25~160 x 160 x WT1.2~8.0 Carbon Steel


Product Name Executive Standard Dimension (mm) Steel Code / Steel Grade
Threaded Steel Pipes DIN 2440 Ø21~164 x WT2.65~4.85 Carbon Steel


Product Name Executive Standard Dimension (mm) Steel Code / Steel Grade
Screwed and Socketed Steel Tubes BS 1387 Ø21.4~113.9 x WT2~3.6 Carbon Steel


Product Name Executive Standard Dimension (mm) Steel Code / Steel Grade
Scaffolding Pipes EN 39 Ø48.3 x WT3.2~4 Carbon Steel


Product Name Executive Standard Dimension (mm) Steel Code / Steel Grade
Carbon Steel Tubes for General Structure Purpose JIS G3444 Ø21.7~216.3 x WT2.0~6.0 Carbon Steel
Carbon Steel Tubes for Machine Structure Purpose JIS G3445 Ø15~76 x WT0.7~3.0 STKM11A, STKM13A
Carbon Steel Pipes for Ordinary Piping JIS G3452 Ø21.9~216.3 x WT2.8~5.8 Carbon Steel
Carbon Steel Pipes for Pressure Service JIS G3454 Ø21.7~216.3 x WT2.8~7.1 Carbon Steel
Carbon Steel Rigid Steel Conduits JIS G8305 Ø21~113.4 x WT1.2~3.5 G16~G104, C19~C75, E19~E75
Carbon Steel Rectangular Pipes for General Structure JIS G3466 16 x 16~150 x 150 x WT0.7~6 Carbon Steel


Advantage of ERW pipe

The alloy content of the coil is often lower than similar grades of steel plate, improving the weldability of the spiral welded pipe. Due to the rolling direction of spiral welded pipe coil is not perpendicular to the pipe axis direction, the crack resistance of the spiral welded pipe materials.

What is welded steel pipe?

Welded steel pipe refers to a steel pipe with seams on the surface that is welded by bending and deforming a steel strip or steel plate into a circular, square or other shape. The blanks used for welded steel pipes are steel sheets or strips.

Since the 1930s, with the rapid development of continuous rolling production of high-quality strip steel and the advancement of welding and inspection technology, the quality of welds has been continuously improved, and the varieties and specifications of welded steel pipes have been increasing.

When the T-shaped welded steel pipe contains Ni, it has strong corrosion resistance in an acidic environment. In an environment containing sulfuric acid or hydrochloric acid, the higher the Ni content in the T-shaped welded steel pipe, the stronger the corrosion resistance. Under normal circumstances, only adding Cr to the T-shaped welded steel pipe can prevent the phenomenon of corrosion. The poor edge condition of the strip is another important cause of misalignment. The effects of changes in mass flow, heat flow density and structural parameters (ratio of helical curvature diameter to T-shaped welded steel pipe diameter Dc/D) on the heat transfer coefficient of saturated bubble boiling in vertical spiral pipes.

During the production of T-shaped welded steel pipes, misalignment occurs from time to time, and there are many influencing factors. In production practice, the steel pipe is often degraded by the wrong side and out of tolerance. Therefore, it is necessary to analyze the reasons for the misalignment of the spiral steel pipe and its preventive measures.

Due to the poor shape and dimensional accuracy of the head and tail of the uncut steel strip, it is easy to cause the steel strip to bend hard and cause misalignment during butt joint. Simulation parameter range: vertical pipe: pipe diameter D=10mm, pipe length L=660mm; three types of vertical T-shaped welded steel pipe: pipe diameter D=10mm, the change of the ratio of the curvature diameter of the T-shaped welded steel pipe to the spiral pipe diameter is Dc /D=15, 20, 25, helical pitch Pt=20mm, tube lengths are L=503mm, L=660mm, L=817mm respectively. Mass flow G=200~400Kg/(m'2 s), heat flux density q=5~15KW/m'2, saturation pressure p, saturation=0.414880MPa, saturation temperature T, saturation=283.15K.

Technical requirements for welded pipes

The technical requirements and inspection of welded pipes are based on the provisions of the GB3092 "Welded Steel Pipes for Low-Pressure Fluid Transmission". It can be delivered according to fixed length or double length. The surface of the steel pipe should be smooth, and defects such as folds, cracks, delamination, and lap welding are not allowed. The surface of the steel pipe is allowed to have minor defects such as scratches, scratches, weld misalignment, burns and scars that do not exceed the negative deviation of the wall thickness. The thickening of the wall thickness and the presence of inner seam weld bars are allowed at the weld.

Welded steel pipes should be subjected to mechanical performance test, flattening test and flaring test, and must meet the requirements of the standard. When the steel pipe should be able to withstand the internal pressure, carry out a pressure test of 2.5Mpa, and keep it for one minute without leakage. The method of eddy current flaw detection is allowed to replace the hydrostatic test. The eddy current flaw detection is carried out according to the standard of GB7735 "Steel tube eddy current flaw detection inspection method". The eddy current flaw detection method is to fix the probe on the frame, keep a distance of 3~5mm between the flaw detection and the weld seam, and conduct a comprehensive scan of the weld seam by the rapid movement of the steel pipe. The flaw detection signal is automatically processed and sorted by the eddy current flaw detector. To achieve the purpose of flaw detection. The welded pipe after the flaw detection is cut off according to the specified length with a flying saw, and it is rolled off the assembly line through the turning frame. Both ends of the steel pipe should be chamfered with flat ends, printed with marks, and the finished pipes are packed in hexagonal bundles before leaving the factory.

Straight seam steel pipe processing method:

Straight seam steel pipe is a steel pipe whose weld seam is parallel to the longitudinal direction of the steel pipe. Generally, its strength is higher than that of straight seam welded pipe. Narrower billets can be used to produce welded pipes with larger diameters, and the same width of billets can be used to produce welded pipes with different pipe diameters. But compared with the straight seam pipe of the same length, the weld length is increased by 30~100%, and the production speed is lower. So what are its processing methods?

  1. Forging steel: a pressure processing method that uses the reciprocating impact force of the forging hammer or the pressure of the press to change the blank into the shape and size we need.
  2. Extrusion: It is a processing method in which steel puts metal in a closed extrusion box and applies pressure at one end to make the metal extrude from the specified die hole to obtain a finished product with the same shape and size. It is mostly used for the production of non-ferrous metals material steel.
  3. Rolling: A pressure processing method in which the steel metal billet passes through the gap between a pair of rotating rolls (various shapes), and the cross-section of the material is reduced due to the compression of the rolls, and the length is increased.
  4. Pulling steel: it is a processing method in which the rolled metal blank (type, pipe, product, etc.) is pulled through the die hole to reduce the cross section and increase the length. Most of them are used for cold processing.

Quenching Technology for Straight Seam Welded Pipe

The surface quenching and tempering heat treatment of straight seam welded pipe is usually carried out by induction heating or flame heating. The main technical parameters are surface hardness, local hardness and effective hardened layer depth. Vickers hardness tester can be used for hardness testing, and Rockwell or superficial Rockwell hardness tester can also be used. When the surface heat treatment hardened layer is thick, the Rockwell hardness tester can also be used. When the thickness of the heat-treated hardened layer is 0.4-0.8mm, the HRA scale can be used, and when the thickness of the hardened layer exceeds 0.8mm, the HRC scale can be used.

If the parts require high local hardness, local quenching heat treatment can be carried out by means of induction heating. Such longitudinal welded pipes usually need to mark the location of local quenching heat treatment and local hardness value on the drawing. Hardness testing of longitudinally welded pipes shall be carried out in the area. The hardness testing instrument can use a Rockwell hardness tester to test the HRC hardness value. If the heat-treated hardened layer is shallow, a surface Rockwell hardness tester can be used to test the HRN hardness value.

The three hardness values of Vickers, Rockwell and Superficial Rockwell can be easily converted to each other and converted into hardness values required by standards, drawings or users. The corresponding conversion tables are given in the international standard ISO, the American standard ASTM and the Chinese standard GB/T.

【H】 Ceramic lined pipe

Ceramic lined pipe is made through self-propagating high-temperature synthesis (SHS) technique.

【H】 Cast basalt lined steel pipe

Cast basalt lined steel pipe is composed by lined with cast basalt pipe, outside steel pipe and cement mortar filling between the two layers.

【H】 Ceramic Tile Lined Pipes

Ceramic tile lined pipes have very uniform coating of specially formulated ceramic material that is affixed to the inner of the pipe.

【H】 Rare earth alloy wear-resistant pipe

The material of the rare earth alloy wear-resistant pipe is ZG40CrMnMoNiSiRe, which is also the grade of rare earth alloy steel.

【H】 Tubes Erosion Shields

Tubes Erosion Shields are used to protect boiler tubing from the highly erosive effects of high temperatures and pressures thereby greatly extending tube life.

【H】 ASTM A213 T91 Alloy Tube

The ASTM A213 T91 seamless tubes are primarily used for boiler, superheater, and heat-exchanger.

Ni-Hard Wearback Pipes Ni-Hard Wearback Pipes