Common problems can be roughly divided into three types, which are uneven coating, dripping of preservatives, and foaming of preservatives.

1. Uneven coating. The fundamental manifestation of this kind of problem is that the preservative is unevenly distributed on the surface of the steel pipe. Some parts are too thickly coated, while some parts are too thin or not coated with oil at all. Therefore, the thickness of the coating in the place where the coating is too thick exceeds the standard, resulting in waste; and the place where the coating is too thin or not covered will reduce the anti-corrosion ability of the steel pipe, resulting in final corrosion.

2. Antiseptic hanging drops. The anticorrosion agent solidifies on the surface of the steel pipe like water droplets, which is the phenomenon of anticorrosion agent hanging drop. The occurrence of this phenomenon often does not directly affect the corrosion resistance, and it can also ensure the corrosion resistance required by the steel pipe; but from the aesthetic point of view, there is no corrosion resistance. The steel pipe with dripping agent looks dull and uneven, which directly affects the appearance of the steel pipe

3. Antiseptic foaming. Due to the air entering the preservative, bubbles are formed in the coating of the steel pipe. These bubbles vary in size according to the specifications of the steel pipe. The shape of the larger air bubbles is like the air bubbles on the protective cover of some home appliance remote controls, and the air bubbles will be broken when pressed with a little force. The foaming phenomenon of anti-corrosion agent not only affects the appearance of the steel pipe, making the surface of the whole steel pipe rough and not smooth, but also the damage of the bubbles will reduce the standard of the coating film thickness, reduce the anti-corrosion ability, and finally lead to the corrosion of the steel pipe where the bubbles are located .

In order to prolong the service life of pipelines, pipeline anti-corrosion construction has become an indispensable process in the pipeline production process; with the continuous development and production of manufacturers, various types of anti-corrosion spiral steel pipes have appeared on the market.

The more common anti-corrosion types of spiral steel pipes on the market are: epoxy resin anti-corrosion, 3PE anti-corrosion, cement mortar anti-corrosion and epoxy asphalt anti-corrosion; different types of anti-corrosion steel pipes have different uses, and spiral welded steel pipes refer to those with seams on the surface. Steel pipes, which are welded with steel plates or steel plates to form round or square shapes;

Spiral steel pipe factory can be divided into arc welded pipe, high frequency resistance welded pipe, low frequency resistance welded pipe, gas welded pipe, furnace welded pipe, etc. according to different welding methods; according to the shape of the weld, it can be divided into straight seam welded pipe and spiral steel pipe, electric welded steel pipe for oil Drilling and machinery manufacturing; furnace welded pipes can be used as water gas pipes, large-diameter longitudinal welded pipes are used for high-pressure oil and gas transportation, spiral steel pipes are used for oil and gas transportation, pipe piles, bridge piers, etc.; compared with seamless steel pipes, welded steel pipes have lower cost and production higher efficiency.

Drinking water anti-corrosion steel pipe topcoat: It is composed of epoxy resin, rubber resin modification, harmless anti-rust pigments, fillers and additives, and has excellent chemical resistance and anti-microbial erosion.

Uses: It is used as primer for water supply pipelines, and topcoat is used for anti-corrosion coating on the inner wall of water supply pipelines; this kind of anti-corrosion is for drinking water pipeline projects, and it is non-polluting and harmless.

Maintenance measures:

1. The product should be stored in a cool, ventilated, dry place, away from fire and heat sources.

2. This product is a thick coat and can be applied in thick coats without sagging. Generally, after opening the barrel, it can be used without adding thinner.

3. After the paint is stored for a long time, there will be slight precipitation, so it should be stirred before use.

4. After the paint is ready, it should be cured for 20 minutes in summer and 1.5-2 hours in winter for construction. Usually use up within 8 hours, otherwise the viscosity will thicken and the application will not be easy.

5. The top coat can be applied after the primer surface is dry. This interval should not exceed two days at room temperature, otherwise the adhesion between the layers will be affected. The time interval between top coats should also allow the surface to dry. Interpenetrating network polymer is a new type of IPN series anti-corrosion coating researched and developed in the past twenty years. It is a copolymer of castor oil-based polyurethane and polysubstituted ethylene interpenetrating network polymer. During the mixing and curing process of paint, the former is rubber, and the latter’s plastic network penetrates into each other, penetrates and firmly adheres to the surface of the object to be coated, thus producing corrosion protection and decorative materials on the surface of the paint.

3PE Coating standard are ANSI/AWWA C104/A21.4 American National Standard for Cement-Mortar Lining for Ductile-Iron Pipe and Fittings for Water, ISO 21809 Petroleum and natural gas industries — External coatings for buried or submerged pipelines used in pipeline transportation systems, DIN 30670 Polyethylen coatings of steel pipes and fittings.

The normal bare pipe will be corroded in the severe environment and its lifetime will be reduced, making the construction and maintenance cost very high. But due to every layer of the 3PE coating system has its good performance, the 3PE coated pipe can protect the pipe in the severe environment and extend its lifetime to 30-50 years even longer. it can significantly reduces the construction and maintainance cost for the pipeline. At the same time, the 3PE coated pipe has favorable thermal insulation property, the thermal losses is just 25% of the traditional pipe, saving a lot of energy cost during operation. At last, the 3PE coated pipe can directly be laid underground or in the water even directly in the frozen earth because of its good anticorrosion property and impact resistance property in the low temperature, no need to construct ditch.

3PE Coating Steel Pipe has good thermal insulation performance, and the heat loss is only 25% of that of traditional pipes. Long-term operation can save a large amount of resources, significantly reduce energy costs, and has strong waterproof and corrosion resistance. With a pipe trench, it can be directly buried in the ground or water. The construction is simple and quick, the overall cost is low, and it has good corrosion resistance and impact resistance under low temperature conditions, and can be directly buried in frozen soil in a certain environment.

According to API5L, GB/T9711.1 pipeline steel pipe performance requirements, according to the different tempering temperature, tempering can be divided into the following:

1. Low temperature tempering (150-250 degrees)

The microstructure obtained by low temperature tempering is tempered martensite. The purpose is to reduce the quenching stress and brittleness of the quenched steel on the premise of maintaining high hardness and high wear resistance, so as to avoid cracking or premature damage during use. It is mainly used for a variety of high carbon cutting tools, measuring tools, API5L,GB/T9711.1 pipeline steel pipe, rolling bearing and carburizing parts, temper hardness is generally HRC58-64.

2.  Moderate tempering (250-500 degrees)

The microstructure obtained by moderate tempering is tempered troxite. The aim is to obtain high yield strength, elastic limit and high toughness. Therefore, it is mainly used for all kinds of API5L,GB/T9711.1 pipeline steel pipe and hot working die treatment, tempered hardness is generally HRC35-50.

3.  High temperature tempering (500-650 degrees)

The microstructure obtained by high temperature tempering is tempered soxite. It is customary to combine quenching and tempering heat treatment called tempering treatment, its purpose is to obtain strength, hardness and plasticity, toughness are better comprehensive mechanical properties. Therefore, it is widely used in automobile, API 5L, GB/T9711.1 pipeline steel pipe, machine tools and other important structural parts, such as connecting rod, bolt, gear and shaft. The hardness after tempering is generally HB200-330.

Mechanical Properties:

1. It is generally suitable for welding of thin steel pipe below 6mm, with the characteristics of beautiful and elegant weld molding and small welding deformation.
2. The maintenance gas is argon with the purity of 99.99%. When the welding current is 50-50A, the argon flow rate is 8-10L/min, and when the current is 50-250A, the argon flow rate is 2-5L/min.
3. The length of the tungsten pole protruding from the gas nozzle is 4-5mm, 2-3mm in the place of poor masking such as fillet welding, 5-6mm in the place of deep grooving, and the interval from the nozzle to the operation generally does not cross 5mm.
4. In order to prevent the appearance of welding pores, it is necessary to clean up the welding parts if there is rust and oil.
5 Welding arc length, welding shallow steel, with 2-4mm is the best, and stainless steel welding, with 3mm is the best, too long maintenance results are not good.
6. When docking the bottom, in order to prevent the back of the bottom weld passage from being oxidized, the back also needs to implement gas maintenance.
7. In order to maintain the welding pool well with argon and facilitate the welding operation, an Angle of 80-85° should be connected between the middle line of the tungsten pole and the workpiece at the welding place, and the general Angle between the filler wire and the workpiece should be as small as possible, generally 0°.
8. Windproof and ventilation. In windy places, please choose the method of retaining the net, and in the room, the appropriate ventilation method should be selected.