API 5L Steel Pipe Piles

Date:2024-07-11Tags:API 5L, Steel Pipe Piles

1.What is steel pile pipe?

Steel pipe piles are products made of steel pipes, mortises, tenons, etc., usually made of seamless steel pipes or welded steel pipes such as SSAW (spiral submerged arc welded pipe) and ERW (electric resistance welded pipe). These steel pipe piles can be overlapped to form arc or circular structures, and are widely used in water enclosure, sand enclosure and other projects, mainly used in offshore wharf construction. Steel pipe piles have the advantages of simple structure, convenient use, good sealing, high strength and good elasticity. The size of steel pipes is diverse, with an outer diameter of 50-120 cm and a wall thickness of 1-1.8 cm.


2.API 5L standard

API 5L is a standard for oil and gas transmission pipelines, which specifies the manufacturing requirements for seamless steel pipe and welded steel pipes, including two product grades (PSL1 and PSL2). In the oil and gas industry, API 5L steel pile pipes have important application value. Especially in offshore wharf construction, construction workers usually use steel pile pipes to block seawater.


3.Application of steel pipe piles

Steel pipe piles are usually welded by spiral steel plates in factories. Commonly used steel pipe piles have an outer diameter of 500 to 1200 mm and a wall thickness of 10 to 18 mm. At present, steel pipe piles are mainly used in offshore docks. Due to the deep waters in the offshore area and the great influence of waves, currents and ship impact forces, steel pipe piles perform particularly well under such working conditions. In addition, offshore construction is greatly affected by climate and ocean hydrology, and the construction progress is required to be fast. The use of steel pipe piles can better solve these problems.


4.What are the advantages and disadvantages of API 5L steel pile pipe?

Advantages of steel pipe piles

High strength: Steel pipe piles have high strength, strong bending resistance, and can withstand large horizontal forces.

Good elasticity: Steel pipe piles have good elasticity and can absorb large deformation energy, reducing the impact force of ships on dock buildings.

Convenient manufacturing and construction: The manufacturing and construction of steel pipe piles are relatively convenient, which can speed up the construction progress of dock buildings.

Disadvantages of steel pipe piles

The disadvantages of steel pipe piles include:

Large amount of steel: Steel pipe piles use a large amount of steel, about 3 to 4 times that of reinforced concrete piles.

High cost: The cost of steel pipe piles is high, about 2 to 3 times that of reinforced concrete piles.

Easy to rust: Steel pipe piles are easy to rust and have poor durability.

Steel Pipe Piles

5.API 5L Steel Pile Pipe Production Process and Inspection

API 5L is the specification standard for steel pipes used to transport oil, natural gas and water. Steel pile pipes play an important role in the oil and gas industry, and their production and inspection processes need to strictly follow the specifications. The following will introduce the production process and various inspection requirements of API 5L steel pile pipes in detail.

Production process

Raw material selection: The first step in producing steel pile pipes is to select suitable steel. Commonly used materials include carbon steel and various grades of alloy steel. The choice of raw materials directly affects the performance and quality of the final product.

Steel pipe forming: Steel pipe forming includes two methods: seamless pipe manufacturing and welded pipe manufacturing. Seamless pipes are formed by heating steel billets and punching and stretching, while welded pipes are formed by rolling flat steel plates into cylindrical shapes and welding them longitudinally.

Heat treatment: After the steel pipe is formed, it needs to undergo a heat treatment process to improve its mechanical properties and eliminate residual stress. Common heat treatment methods include annealing, quenching and tempering.

Dimension control: The outer diameter and wall thickness of the steel pipe are precisely controlled by sizing rollers or dies to ensure that it meets the standards and customer specifications.

Cutting and Length Control: Cut the steel pipe to the required length and prepare the ends for subsequent threading or connection.

Threading: Most steel pile pipes need to be threaded at both ends to allow for easy assembly and disassembly on site. Specialized machines are used to cut the threads on the pipe ends.

Surface Treatment: Steel pile pipes require surface treatment such as phosphate coating or other protective coatings to improve their corrosion resistance and extend their service life.

Marking and Identification: Each steel pipe is marked with important information, including size, material grade, furnace batch number, manufacturer name or logo, and other required identifiers.


6.Flattening test of API 5L steel pile pipe

Flattening test is an important step in inspecting the quality of steel pipes, and usually follows the requirements of ISO 8492 or ASTM A370. The specimens are taken from both ends of the steel strip, and the welds of two specimens are placed at 6 o'clock or 12 o'clock for flattening test, and the welds of the other two specimens are placed at 3 o'clock or 9 o'clock for flattening test. For the specimens cut from the cut end when welding is stopped, the weld should be placed at 3 o'clock or 9 o'clock for flattening test.


7.Hardness test of API 5L steel pile pipe

When suspicious hard blocks are found during visual inspection, a portable hardness tester (in accordance with the requirements of ASTM A956, ASTM A1038 or ASTM E110) should be used to perform hardness tests in accordance with the requirements of ISO 6506, ISO 6507, ISO 6508 or ASTM A370 to ensure that the hardness of the steel pipe meets the standards.


8.Hydrostatic pressure test of API 5L steel pile pipe

Hydrostatic pressure test is a key inspection step to ensure that the steel pipe is leak-free under high pressure conditions. The stabilization time for all sizes of seamless pipes and welded pipes with a diameter less than 457 mm shall not be less than 5 seconds, and the stabilization time for welded pipes with a diameter greater than 457 mm shall not be less than 10 seconds. In order to ensure that each steel pipe can be hydrostatically tested at the required test pressure, each testing machine shall be equipped with a recorder that can record the test pressure and test stabilization time of each steel pipe.


9.Dimensional inspection of API 5L steel pile pipe

The diameter of the steel pipe shall be measured at least once every 4 hours per work shift to verify whether it meets the standard diameter deviation. The diameter shall be measured using a tape measure, micrometer, ring gauge, caliper, ellipsometry, coordinate measuring machine or optical measuring instrument. For steel pipes with a diameter greater than 508 mm, a ruler shall be used for arbitration in case of dispute.


The production process and inspection process of steel pile pipes need to strictly follow the API 5L standard. The production process includes raw material selection, steel pipe forming (including seamless pipe and welded pipe manufacturing), heat treatment, size control, cutting and length control, thread processing, surface treatment and other steps. In addition, it also includes flattening test, hardness test, macro inspection, metallographic inspection, hydrostatic pressure test, size inspection, weighing and non-destructive inspection to ensure that the quality and performance of steel pile pipes meet the standard requirements.


In summary, API 5L steel pile pipes not only have the advantages of high strength, high bending resistance and good elasticity, but also can effectively cope with the harsh environmental requirements of offshore construction. However, due to its high cost, easy to rust and limited durability, it needs to be comprehensively considered when selecting and using it.

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