Advantages of spiral submerged arc welded steel pipes:

1. Using steel strips of the same width, steel pipes of different diameters can be produced, especially large-diameter steel pipes can be produced using narrow strip steel.
2. Under the same pressure conditions, the stress borne by the spiral weld is less than that of the straight seam welded pipe, which is 75% to 90% of that of the straight seam welded pipe; thus, it can withstand greater pressure. Compared with the straight seam welded pipe of the same outer diameter, the wall thickness can be reduced by 10% to 25% under the same pressure.
3. Accurate dimensions, generally with a diameter tolerance of no more than 0.12%, deflection less than 1/2000, and ellipticity less than 1%, generally eliminating the need for sizing and straightening processes.
4. Continuous production is possible. Theoretically, infinitely long steel pipes can be produced, with minimal cutting and tail-cutting losses, increasing metal utilization by 6% to 8%.
5. Compared with straight seam welded pipes, it is more flexible in operation and easier to change types and adjust.
6. Lightweight equipment and low initial investment. It can be manufactured into trailer-mounted mobile units, allowing welded pipes to be produced directly at the pipeline laying construction site.
7. It is easy to achieve mechanization and automation.
Disadvantages of spiral submerged arc welded steel pipes: Because rolled steel is used as raw material, its crescent shape has a certain degree of curvature, and the welding point is located in the edge area of the elastic strip steel, making it difficult to align the welding torch and affecting the welding quality. 

Density is a measure of mass within a specific volume. Density equals the mass of an object divided by its volume and is represented by the symbol ρ.
In the International System of Units (SI) and Chinese legal units of measurement, density is measured in kilograms per cubic meter (kg/m³). Other units are expressed in g/cm³ (note: 1 g/cm³ = 1000 kg/m³).
The density varies slightly depending on the type of stainless steel. 304 stainless steel has a density of approximately 7.93 g/cm³, while 316 stainless steel has a density of approximately 8.0 g/cm³.
There are many grades of stainless steel, but the density of most types generally fluctuates between 7.7 and 8.0 g/cm³.

Shipbuilding steel plate materials are mainly composed of iron, carbon, and small amounts of alloying elements. Iron is the primary component; carbon increases the strength and hardness of the plate, while alloying elements improve its corrosion resistance and other properties.

The manufacturing process of steel ship plates includes two processes: hot rolling and cold rolling. Hot rolling involves melting iron ore at high temperatures into molten steel, then processing it into steel plates of a certain thickness using a rolling mill. Cold rolling involves processing hot-rolled steel plates through pickling, cold rolling, and annealing to achieve a steel plate with a specific thickness and surface quality.

The advantages of steel ship plates include high strength, high hardness, and good corrosion resistance. Their disadvantages include significant weight, which is detrimental to lightweight ship design. Additionally, steel ship plates are relatively expensive.