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Construction Technology of Pile Driving Spiral Steel Pipe

Date:2021-10-12    keywords:pile driving spiral steel pipe, piling construction

Piling spiral steel pipe(SSAW) is a spiral seam steel pipe made of strip steel coils as raw materials, often extruded and formed by automatic double-wire double-sided submerged arc welding. So, what is the piling spiral tube like during construction? How is the piling spiral tube produced? The following spiral tube manufacturers will introduce to you.


piling construction


1. Penetration of piling pipe

1) Before construction, the control of sample piles should be rechecked one by one according to the original design drawing and the proposed axis line, and the measurement records should be made. Piling construction can only be carried out after the recheck is correct. After the pile-driving spiral pipe pile is transported to the site, it is hoisted with one-point lashing when it is hoisted to the pile position to insert the pile, and the pile-driving spiral pipe pile is aligned with the previously released pile position to ensure that the penetration is accurate and vertical. Before pile driving, a special pile cap must be placed on the pile head, and a hardwood damping pad must be placed on the pile cap. Placed on the top of the pile, it will self-sink, and a large amount of penetration will penetrate into the soil. After it is settled to stability, hammering will be carried out;

2) At the beginning of piling, the piling opportunity will be driven empty due to the large penetration. When starting the hammering operation, the test driving should be slowly interrupted until the pile enters a certain depth of the ground, and continuous hammering shall not be allowed. Piling process
In the process, the verticality of the guide rod of the pile driver and the pile must be corrected at any time, and the pile hammer, pile cap and pile must be kept on the same longitudinal axis;

3) After the pile-driving spiral pipe pile is driven into 1 ~ 2m, the verticality should be re-corrected. When the pile is driven to a certain depth and the quality of the piling is good, then continue to be beaten until it is 60cm~80cm above the water surface to stop the hammering. Connect the piles and repeat the above steps until the design elevation is reached. If the pile position is found to be inclined during the construction process (>1/100L L: steel pile length), it should be adjusted in time or pulled out the steel pipe pile and re-construction;


4) The buried depth of pile driving spiral pipe pile: 10m through the riverbed, and the sinking amount within one minute of percussion does not exceed 5mm.


Pier piling construction


2. Connect the pile

The pile-driving spiral pipe pile body connection adopts the butt welding of the pile body up and down. Before welding, the deformed and damaged part of the lower pile pipe must be trimmed, and the rust, water or oil sludge sand at the end of the upper pile pipe must be removed and polished.
Make good welding joints so that the gap between the upper and lower piles is 2 ~ 4mm. At the same time, multi-layer welding is used. After each layer of welding seam is welded, the welding slag should be removed in time, and the appearance inspection should be carried out.Add welding block to strengthen the connection of the upper and lower piles. After welding, it must be cooled for more than 5 minutes before hammering and piling.

3. Welded pile cover

After the construction of the pile-driving spiral pipe pile is completed, sand is manually poured into the pile to the top of the pile, and the pile cover is welded on the upper part of the steel pipe pile, and at the same time, 8 to 12 anchor steel bars of 20 mm are welded on the outer wall.


Pile driving spiral pipe production process:

(1) The raw materials are strip steel coils, welding wires, and fluxes. Strict physical and chemical inspections are required before investment.
(2) Butt joint of strip steel head and tail, using single wire or double wire submerged arc welding, after coiling into steel pipe, automatic submerged arc welding is used for repair welding.
(3) Before forming, the strip undergoes leveling, edge trimming, edge planing, surface cleaning and conveying, and pre-bending treatment.

(4) The electric contact force meter is used to control the pressure of the cylinders on both sides of the conveyor to ensure the smooth conveying of the strip.
(5) Externally controlled or internally controlled roller molding is adopted.

(6) The weld gap control device is used to ensure that the weld gap meets the welding requirements, and the pipe diameter, the amount of misalignment and the weld gap are all strictly controlled.



Spiral steel pipe - SSAW


(7) Both internal welding and external welding adopt American Lincoln electric welding machine for single-wire or double-wire submerged arc welding, so as to obtain stable welding quality.
(8) The welded seams are all inspected by the online continuous ultrasonic automatic flaw instrument, which guarantees 100% non-destructive testing coverage of the spiral welds. If there is a defect, it will automatically alarm and spray the mark, and the production workers will adjust the process parameters at any time according to this to eliminate the defect in time.


(9) Use an air plasma cutting machine to cut the steel pipe into individual pieces.

(10) After cutting into a single steel pipe, each batch of steel pipes must undergo a strict first inspection system to check the mechanical properties, chemical composition, melting condition of the weld, the surface quality of the steel pipe and the non-destructive inspection to ensure that the pipe manufacturing process is qualified. Only later can it be officially put into production.


(11) The parts with continuous sonic flaw detection marks on the welds are re-examined by manual ultrasonic and X-ray.
eliminate.
(12) The pipes where the butt-welded seams of Fe-steel and the J-joint intersecting with the spiral welds are all inspected by X-ray television or filming.
(13) Each steel pipe undergoes a hydrostatic pressure test, and the force adopts a radial seal. The test pressure and time are strictly controlled by the steel pipe hydraulic microcomputer detection device. The test parameters are automatically printed and recorded.

(14) The pipe end is machined to accurately control the verticality of the end face, the bevel angle and the obtuse edg.


Tips: ERW welded pipe is formed by rolling strip and welding the seam, with tighter dimensional tolerances and less weight. The weld seam is heat treated after welding that no untempered martensite remains, and the weld flash can be removed from both inner and outer surfaces. ASTM A53 ERW steel pipe is a typical carbon steel pipe. It is largely used to convey fluids at low / medium pressures such as oil, gas, steam, water, air and also for mechanical applications.

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