1. Basic introduction of steel pipe

(1) Profiles

With hollow cross-sections, the length of steel pipes is much greater than their diameter or circumference. They are not only used to transport fluids and powdered solids, exchange heat energy and manufacture mechanical parts and containers, but they’re also an economical steel.

(2) Classification

• Shape of cross-sections: Hollow (round), square, rectangular and shaped etc.

• Material: carbon steel, alloy steel, duplex steel and composite steel etc.

• Manufacturing technique: seamless, welded.

• Usage: Transportation pipeline, engineering structure, thermal equipment, petrochemical industry, machinery manufacturing, geological drilling, high pressure equipment with steel pipes etc.

2. Types & Features

(1) Electro galvanizing welded pipe

The zinc layer is simply attached to the steel tube matrix and easy to fall off.

• Welding process: Arc welded, high frequency or low frequency resistance welded, gas welded, furnace welded etc.

• Welding form: Straight seam welded pipe and spiral welded pipe.

• Manufacturing methods: Hot dip galvanizing and electric galvanizing.

• Standard: GB, ASTM, DIN etc.

• Usage Pipelines for conveying water, gas, oil and other general pressure liquids, oil well pipes in offshore oil fields, oil pipelines, oil heaters and condensing coolers for chemical coking equipment of petroleum industry.

• Feature: Poor corrosion resistance, do not use for water, gas pipes etc.

(2) Square welded pipe

It's made of steel strips after processing. Generally, the steel strips are unpacked, flattened, curled, and welded to form round tubes, which are then rolled into square tubes and cut into required lengths.

• Material: stainless steel, duplex steel, carbon steel, low alloy steel, alloy steel etc.

• Technique: Arc welded, electric resistance welded (high frequency, low frequency), gas welded, furnace welded.

• Standard: GB, ASTM, EN, JIS, GOST etc.

• Usage: Construction, machinery manufacturing, steel construction projects, shipbuilding, solar power generation brackets, steel structure engineering, power engineering, power plants, agricultural and chemical machinery etc.

• Feature: Fewer parts, easy to install and disassemble.

(3) Rectangular welded pipe

It is made by bending steel strips or steel plates into rectangular shape and then welding them.

• Material: stainless steel, duplex steel, carbon steel, low alloy steel, alloy steel etc.

• Technique: Arc welded, electric resistance welded (high frequency, low frequency), gas welded, furnace welded.

• Standard: GB, ASTM, JIS, GOST etc.

• Usage: Steel construction projects, shipbuilding, solar power generation support, power engineering, agricultural and chemical machinery.

• Feature： At the same time of bending and torsional strength, the weight is light, so it is widely used in the manufacture of mechanical parts and engineering structures.

(4) Spiral welded pipe

Spiral steel pipe is made of strip steel coil as raw material, extruded at room temperature, and welded by submerged arc welding process.

• Material: Material: stainless steel, duplex steel, carbon steel, low alloy steel, alloy steel etc.

• Technique: Double-sided buried fox welding, single-sided buried fox welding.

•  Usage: Spiral steel pipe for fluid transportation, spiral steel pipe for piles.

• Standard: GB, ASTM, JIS, GOST etc.

• Feature: Strong corrosion resistance and plasticity.

(5) Hot-dip galvanized welded pipe

Hot-dip galvanized welded pipes are formed by the reaction of metal and iron matrix to form an alloy layer. The iron oxide on the surface is removed by pickling, then washed in zinc chloride or ammonium chloride aqueous solution, and finally placed in a hot-dip galvanizing tank.

• Welding technique: Arc welded, electric resistance welded (high frequency, low frequency), gas welded, furnace welded.

• Welding form: Straight seam welded pipe and spiral welded pipe.

• Manufacturing methods: Hot dip galvanizing and electric galvanizing.

• Standard: GB, ASTM, DIN etc.

• Feature: Uniform coating, strong adhesion, long service life.

(6) Sanitary galvanized welded pipe

It is a steel pipe made of steel or steel strip after being curled and formed by a machine unit and a mold and then welded.

• Welding form: Automatic welding and manual welding.

• Standard: GB, ASTM, JIS, DIN etc.

• Usage: Pharmaceutical, Food etc.

(7) Ordinary welded pipe

Generally, ordinary welded pipesare used to transport low-pressure fluids and made of Q195A, Q215A, Q235A steel.

• Material: stainless steel, duplex steel, low alloy steel etc.

• Shape: Ellipse, triangle, L shape, star anise, mushroom type, etc.

• Connection: Welded type, clamp type, thread type etc.

• Standard: ASTM, DIN, JIS, GOST, ISO etc.

• Feature: Simple production process, low cost.

• Usage:  Water engineering, petrochemical industry, chemical industry, electric power industry, agricultural irrigation, urban construction.

From materials to applications, understand the basic knowledge of steel pipe!