Analysis of Key Points of Pipeline Welding Technology and Process Requirements

 

Pipeline welding is the core process for connecting pipelines. It has high technical requirements and complex operations, directly affecting the sealing performance, strength, and service life of the pipeline system. This article elaborates from multiple dimensions such as welding methods, construction specifications, and precautions, providing a practical guide for practitioners.

 

I. Common Pipeline Welding Methods

1. Shielded Metal Arc Welding (SMAW)

It achieves connection by melting the electrode and the workpiece through arc heat. It is suitable for materials such as carbon steel and low - alloy steel. The operation is flexible, but welding parameters need to be controlled to avoid problems such as porosity and slag inclusions.

2. Gas Metal Arc Welding (GMAW) / Gas Tungsten Arc Welding (GTAW)

It uses inert gas to isolate air and protect the molten pool. It is suitable for fine welding of materials such as stainless steel and aluminum alloy, with high - quality welds and small deformation.

3. Laser Welding

A high - energy - density laser beam is used to achieve local melting. It is suitable for pipelines with high - strength and high - precision requirements, such as thin - walled or precision equipment.

4. Ultrasonic Welding

It softens the material interface through mechanical vibration. It is suitable for low - melting - point metal and non - metal pipelines. The operation does not require high temperature, which is energy - saving and efficient.

 

II. Requirements for Welding Construction Technology

1. Pipeline Pretreatment

 - The inclination deviation of the cut end face should be less than 1% of the pipe outer diameter and no more than 3 mm.

 - The groove processing should be carried out according to the welding plan, and the surface should be smooth without defects such as burrs and oxides.

2. Specification for Weld Position

 - The distance from the weld to the starting point of the elbow should be no less than the pipe outer diameter or 100 mm.

 - The distance between adjacent butt welds should be greater than 5 mm, and the position of the support and hanger should avoid the weld by at least 50 mm.

3. Pipe Prefabrication and Installation

 - Select pipe fittings according to the single - line drawing, mark the system number and prefabrication sequence, and the closed pipe section should be processed according to the measured size.

 - The support processing should comply with the standard atlas. The sliding surface should be smooth without jamming and be anti - corrosion treated.

 

III. Quality Control and Safety Key Points

1. Welding Process Control

 - Heat the pipeline uniformly to avoid lack of fusion or burn - through due to uneven temperature.

 - Adopt the multi - layer and multi - pass welding process to reduce the risk of lack of fusion in the groove, and the welding slag of each layer should be thoroughly cleaned.

2. Weld Inspection and Testing

 - The appearance inspection should show no defects such as cracks and porosity, and non - destructive testing should be combined to check the internal quality.

 - Pressure tests and air - tightness tests should be carried out to ensure that the pipeline meets the design and specification standards.

3. Safety Operation Specifications

 - Use protective equipment and ventilation facilities to prevent the accumulation of harmful gases.

 - Strictly comply with the fire - prevention and explosion - prevention regulations, especially when working on pipelines for high - risk media (such as gas and liquid oxygen).

 

IV. Case Analysis: Welding Optimization of an Offshore Jacket

An offshore project uses high - current and long - distance welding technology, combined with an intelligent parameter adjustment system, to improve the quality of multi - layer groove welding and reduce the repair rate by 15%. The equipment supports the switching of multiple processes, increasing the utilization rate by 30%, reducing the risk of poor fusion, and significantly improving the overall efficiency.