SSAW Steel Pipe is spiral seam submerged arc welded steel pipe, which is widely used in various projects. Different application environments have different anti-corrosion requirements. The following will deeply analyze the anti-corrosion treatment methods of SSAW steel pipes in common application environments.

Oil and gas transportation field

Environmental characteristics: The transportation medium contains corrosive components such as hydrogen sulfide and carbon dioxide, and the pipeline is often buried deep underground. The soil environment is complex, such as saline-alkali soil with strong corrosiveness.

Anti-corrosion means

3LPE coating: It is composed of epoxy powder bottom layer, adhesive middle layer and polyethylene outer layer. It can effectively isolate corrosive media and has strong resistance to mechanical damage. It is widely used in long-distance oil and gas pipelines and can significantly reduce the risk of corrosion.

Double-layer epoxy powder coating: It has excellent adhesion, chemical corrosion resistance and cathodic stripping resistance. It performs well in oil and gas transportation containing corrosive media and can ensure long-term stable operation of pipelines.

Sacrificial anode cathodic protection: It is often used in combination with coating. In areas with low soil resistivity and strong corrosion, sacrificial anodes can provide cathodic current for steel pipes, inhibit corrosion, and extend the service life of pipelines.

Scope of water supply and drainage engineering

Environmental characteristics: The pH and hardness of the transported water are different. The water may contain microorganisms, dissolved oxygen, etc., which are easy to cause corrosion. In addition, changes in groundwater levels and soil moisture affect the external environment of the pipeline.

Anti-corrosion methods

Cement mortar lining: Applying cement mortar on the inner wall of the steel pipe can prevent water from directly contacting the pipe wall, reduce corrosion, reduce water flow resistance, and improve water transmission efficiency. It is widely used in drinking water and sewage pipelines.

Epoxy coal tar coating: The price is relatively low, with good water resistance and adhesion. It is suitable for sewage pipes and can effectively resist the erosion of acid and alkali substances in sewage.

Zinc-coating: Contains high-purity zinc powder, which can provide long-term protection in water supply and drainage pipelines through the dual effects of electrochemical protection and barrier protection, and has no pollution to water quality.

Marine engineering field

Environmental conditions: Seawater has high salt content and strong conductivity. The marine environment has high humidity and large temperature changes. There are also problems such as marine biological attachment, which seriously corrodes steel pipes.

Anti-corrosion strategy

Thermal spraying zinc-aluminum coating: thermally spraying zinc-aluminum metal coating on the surface of steel pipe to form a dense protective layer, using the sacrificial anode effect of zinc and aluminum to protect the steel pipe, combined with organic closed coating, can significantly improve the anti-corrosion performance, suitable for offshore platforms, cross-sea pipelines, etc.

Heavy anti-corrosion coating: such as thick paste epoxy coating, polyurethane coating, etc., have excellent seawater corrosion resistance, wear resistance and impact resistance, can provide effective protection for steel pipes in complex marine environments.

Expressed current cathodic protection: by installing auxiliary anodes, applying cathode current to the steel pipe to offset the corrosion current, and cooperating with the anti-corrosion coating, it can greatly extend the service life of the steel pipe in the marine environment.

The cost of anti-corrosion treatment of SSAW steel pipes is affected by many factors, such as anti-corrosion methods, steel pipe specifications (pipe diameter, wall thickness), market raw material price fluctuations, etc. The following introduces the approximate cost range of common anti-corrosion treatment methods:

Oil and gas transportation field

3LPE coating: In terms of direct material cost, based on common specifications, epoxy powder is about 0.3kg/m², and the cost is about 7.5 yuan/m² at 25 yuan/kg; PE (ordinary grade) is 2.4kg/m², 15 yuan/kg, and the cost is about 36 yuan/m²; adhesive is about 8 yuan/m²; accessories (cloth rope, kraft paper, steel shot, water, etc.) are about 5 yuan/m², and the subtotal of direct material cost is about 56.5 yuan/m². Adding electricity costs (taking the anti-corrosion speed of 4 meters per minute for 8 hours of production as an example, a 48-diameter pipeline costs about 2.7 yuan per meter, and the thicker the diameter, the more electricity it consumes per meter), equipment depreciation (calculated based on an annual production of 500,000 meters, about 0.8 yuan per meter), personnel costs (four shifts, 8 people per shift, about 2.9 yuan per meter), management costs (including loading and unloading fees, about 0.4 yuan per meter), etc., the overall cost may be around 60-80 yuan per square meter within a certain diameter range. If calculated by ton, due to the different weights per meter of steel pipes with different diameters and wall thicknesses, assuming common medium-sized steel pipes, the price per ton may be 1,500-5,000 yuan.

Double-layer epoxy powder coating: Compared with 3LPE coating, the amount of epoxy powder used in its direct material cost may be more, and coupled with higher process requirements, the overall cost is generally slightly higher than 3LPE coating, the cost per square meter may be around 70-90 yuan, and the price per ton may be 2,000-6,000 yuan.

Sacrificial anode cathodic protection: The cost of sacrificial anode materials (such as magnesium alloy anodes and zinc alloy anodes) varies according to the specifications and types of anodes. Taking magnesium alloy anodes as an example, the price of a single anode may range from several hundred yuan to thousands of yuan. In addition, the cost of anode installation, etc., must also be considered. However, this method is often combined with coatings. When calculated separately, the cost per kilometer may be tens of thousands of yuan (including materials and installation), which is related to the soil environment, anode spacing setting, etc.

Water supply and drainage engineering scope

Cement mortar lining: The material cost is relatively low, mainly cement, sand, etc., and the cost per square meter may be around 20-40 yuan. However, the construction process involves the coating process, and the labor cost accounts for a large proportion. On the whole, the cost per ton may be 1000-3000 yuan.

Epoxy coal tar coating: In terms of direct material cost, the price of epoxy coal tar coating is relatively affordable. With the common coating thickness requirements, the material cost per square meter may be around 15-30 yuan. With the construction cost, the overall cost per square meter is around 30-50 yuan, and the price per ton is roughly 1000-3000 yuan.

Zinc-coating: Since zinc-coating contains high-purity zinc powder, the material cost is relatively high. The material cost per square meter may be around 40-60 yuan. With the construction cost, the cost per square meter is around 50-80 yuan, and the cost per ton may be 1500-4000 yuan.

Marine engineering field

Thermal spraying zinc-aluminum coating: The equipment investment is large, and the materials are zinc-aluminum metals, etc. The material cost per square meter may be around 50-80 yuan. With the thermal spraying process cost, the cost per square meter is around 80-120 yuan. If the subsequent organic sealing coating cost is included, the overall cost per square meter may exceed 120 yuan. Calculated by ton, due to the complexity of steel pipe specifications and processes, the cost per ton may be 3,000-8,000 yuan.

Heavy anti-corrosion coating: The prices of thick paste epoxy coatings, polyurethane coatings, etc. vary greatly due to different brands and performance. Taking common products as an example, the material cost per square meter may be around 30-60 yuan, and the construction cost is also high. The overall cost per square meter is around 60-100 yuan, and the cost per ton may be 2,000-6,000 yuan.

Impressed current cathodic protection: Auxiliary anodes, power supply equipment, etc. need to be installed. The equipment cost is high. The initial investment cost may be more than 100,000 yuan per kilometer, and the subsequent maintenance cost may also cost tens of thousands of yuan per kilometer per year, which is related to the marine environment, pipeline length, etc.