Seamless steel pipe and galvanized pipe are two common types of steel pipes. Their main differences lie in the manufacturing process and surface treatment, which leads to differences in performance, use and cost. Understanding these differences between seamless steel pipe and galvanized pipe helps to choose the right steel pipe according to specific applications. The following 5 major differences between seamless steel pipe and galvanized pipe are carefully summarized:
1. Differences in manufacturing processes of seamless steel pipes and galvanized pipes:
Seamless steel pipe: Made of a whole piece of metal with no seams on the surface. Its production process mainly includes hot rolling, cold rolling or hot extrusion.
Hot rolling: The heated tube billet is rolled into shape on a rolling mill.
Cold rolling: The hot rolled tube is used as raw material and rolled at room temperature.
Hot extrusion: The heated tube billet is extruded into shape through a die in an extruder.
Galvanized pipe: Galvanized pipe is a steel pipe that is galvanized on the surface. Galvanizing can be performed on welded steel pipes or seamless steel pipes. In other words, galvanized pipes can be welded pipes or seamless pipes.
Hot-dip galvanizing: Immerse the steel pipe in molten zinc to form a zinc layer on its surface.
Cold galvanizing (electrogalvanizing): A layer of zinc is plated on the surface of the steel pipe by electrolysis.
2. The difference between the appearance of seamless steel pipe and galvanized pipe:
Seamless steel pipe: There is no weld on the surface, and the integrity is good.
Galvanized pipe: There is a zinc layer on the surface, showing the unique luster of zinc. If it is a welded galvanized pipe, the weld can be seen.
3. Differences in performance between seamless steel pipes and galvanized pipes:
Corrosion resistance: Galvanized pipes have better corrosion resistance than ordinary seamless steel pipes because of the protection of the zinc layer on the surface. The zinc layer can effectively prevent the steel pipe from rusting.
Pressure bearing capacity: Seamless steel pipes have good integrity due to the lack of welds and can withstand higher pressures.
Weight: Generally speaking, galvanized pipes of the same specifications are lighter than seamless steel pipes because the density of the zinc layer is lower than that of steel and the galvanized layer is relatively thin. However, if the galvanized pipe is a thick-walled seamless pipe, the weight difference is not much, and may even exceed that of an ordinary thin-walled seamless pipe.
4. The difference between the uses of seamless steel pipes and galvanized pipes:
Seamless steel pipe: Due to its strong pressure bearing capacity, it is mainly used for conveying high-pressure fluids (such as oil and natural gas), manufacturing boilers, pressure vessels, hydraulic props and other occasions with high safety and reliability requirements.
Galvanized pipe: Due to its good corrosion resistance, it is mainly used for conveying low-pressure fluids such as water and gas, as well as for building structures, fences, guardrails, balcony guardrails and other occasions with high rust prevention requirements.
5. The difference between the cost of seamless steel pipe and galvanized pipe:
The cost of ordinary seamless steel pipe is generally higher than that of ordinary welded steel pipe.
The cost of galvanized pipe is usually higher than that of ordinary seamless steel pipe and ordinary welded steel pipe because galvanizing requires additional processing steps, but the specific cost comparison depends on the thickness of the galvanized layer and the price of the base pipe itself.
Read more: How to Test the High Temperature Resistance of Seamless Steel Pipes?
1. Differences in manufacturing processes of seamless steel pipes and galvanized pipes:
Seamless steel pipe: Made of a whole piece of metal with no seams on the surface. Its production process mainly includes hot rolling, cold rolling or hot extrusion.
Hot rolling: The heated tube billet is rolled into shape on a rolling mill.
Cold rolling: The hot rolled tube is used as raw material and rolled at room temperature.
Hot extrusion: The heated tube billet is extruded into shape through a die in an extruder.
Galvanized pipe: Galvanized pipe is a steel pipe that is galvanized on the surface. Galvanizing can be performed on welded steel pipes or seamless steel pipes. In other words, galvanized pipes can be welded pipes or seamless pipes.
Hot-dip galvanizing: Immerse the steel pipe in molten zinc to form a zinc layer on its surface.
Cold galvanizing (electrogalvanizing): A layer of zinc is plated on the surface of the steel pipe by electrolysis.
2. The difference between the appearance of seamless steel pipe and galvanized pipe:
Seamless steel pipe: There is no weld on the surface, and the integrity is good.
Galvanized pipe: There is a zinc layer on the surface, showing the unique luster of zinc. If it is a welded galvanized pipe, the weld can be seen.
3. Differences in performance between seamless steel pipes and galvanized pipes:
Corrosion resistance: Galvanized pipes have better corrosion resistance than ordinary seamless steel pipes because of the protection of the zinc layer on the surface. The zinc layer can effectively prevent the steel pipe from rusting.
Pressure bearing capacity: Seamless steel pipes have good integrity due to the lack of welds and can withstand higher pressures.
Weight: Generally speaking, galvanized pipes of the same specifications are lighter than seamless steel pipes because the density of the zinc layer is lower than that of steel and the galvanized layer is relatively thin. However, if the galvanized pipe is a thick-walled seamless pipe, the weight difference is not much, and may even exceed that of an ordinary thin-walled seamless pipe.
4. The difference between the uses of seamless steel pipes and galvanized pipes:
Seamless steel pipe: Due to its strong pressure bearing capacity, it is mainly used for conveying high-pressure fluids (such as oil and natural gas), manufacturing boilers, pressure vessels, hydraulic props and other occasions with high safety and reliability requirements.
Galvanized pipe: Due to its good corrosion resistance, it is mainly used for conveying low-pressure fluids such as water and gas, as well as for building structures, fences, guardrails, balcony guardrails and other occasions with high rust prevention requirements.
5. The difference between the cost of seamless steel pipe and galvanized pipe:
The cost of ordinary seamless steel pipe is generally higher than that of ordinary welded steel pipe.
The cost of galvanized pipe is usually higher than that of ordinary seamless steel pipe and ordinary welded steel pipe because galvanizing requires additional processing steps, but the specific cost comparison depends on the thickness of the galvanized layer and the price of the base pipe itself.
Read more: How to Test the High Temperature Resistance of Seamless Steel Pipes?
