What is Pipe Lay: Its meaning and Types?

What is pipe lay?

Pipe lay is the process of welding pipe joints on the pipe lay vessel. It is a highly skilled and dangerous job, as the welders are working on ship welding. The inspection, testing and coating on weld are all important aspects of pipe lay.

Pipe lay is the process of welding pipe joints (usually for oil and gas transmission pipelines) on the pipe lay vessel, on ship welding, inspection, testing and coating on weld. This process is used to construct subsea pipelines. Pipe lay can be a complex process, but it is an important part of many construction projects.

Pipe lay
Ref: Vanoord

The pipe lay method involves four main steps:

1) Welding: This step involves welding the pipe segments together using an automatic or semi-automatic welding machine (Usually GMAW/FCAW/ SAW). The welding is carried out on the ship itself & it is continuous welding operation.

2) Inspection: Once the pipes are welded together, they need to be inspected for defects. This is done by using a variety of methods, such as X-ray, ultrasonic, or magnetic particle inspection.

3) Testing: After the pipes have been welded and inspected, they need to be tested for strength and durability.

4) Coating: After welding joints are acceptable by testing (VT & NDT) they are coated to prevent corrosion of welded area.

The types of pipe lay

Pipe lay is the process of installing pipelines underwater. The term can also refer to the method used to install the pipeline, which can be either horizontal or vertical.

There are three main types of pipe lay:

  • S-lay,
  • J-lay, and
  • Reel-lay.

S-lay is the most common type of pipe lay, and involves laying the pipe in a spiral pattern around a central point. This method is typically used for large diameter pipelines, as it allows for a more even distribution of weight.

J-lay is similar to S-lay, but the pipe is laid in a straight line rather than a spiral. This method is often used for smaller diameter pipelines, as it requires less space. Reel-lay is the third type of pipe lay, and involves laying the pipe on a spool before it is lowered into place.

Pipe Lay Vessel or Barge

A pipe-laying vessel or barge is a specialized ship used to install pipelines underwater. These vessels are equipped with heavy cranes and other machinery to lay the pipe on the seabed and connect it to other sections of pipeline.

Pipe-laying vessels are used for a variety of underwater construction projects, including the installation of oil and gas pipelines, water lines, and sewer lines. These ships are also used to repair and replace existing pipelines.

Pipe-laying vessels vary in size and capacity, depending on the specific project they are being used for. Some of these ships can carry up to 10,000 tons of pipe, while others are smaller and only carry a few hundred tons.

Pipe Laying Vessel Types

Pipe laying vessels are used to install pipelines on the seabed. The most common type of pipe laying vessel is the pipelaying barge.

Pipelaying barges have a large flat deck, which is used to store sections of pipeline. A crane is used to lower sections of pipeline into the water, where they are welded together. The barges also have powerful pumps, which are used to fill the pipeline with water. This helps to keep the pipeline in place on the seabed.

Pipelaying ships are another type of pipe laying vessel. These ships have a long, metal structure called a stinger, which is used to support sections of pipeline as they are lowered into the water. The stinger is also used to weld sections of pipeline together.

The benefits of pipe lay

Pipe lay is the process of installing pipelines underwater. This method is used to install both small and large diameter pipelines. Pipe lay is a cost-effective way to install pipelines, and it can be used in a variety of environments, including deep water, shallow water, and on land.

Pipe lay has a number of benefits over other methods of pipeline installation. First, pipe lay is less disruptive to the environment than other methods. Second, pipe lay is faster and more efficient than other methods, which reduces the overall cost of the project.

Third, pipe lay allows for a higher degree of accuracy than other methods, ensuring that the pipeline is installed in the correct location. Finally, pipe lay minimizes the risk of damage to the pipeline during installation.

Pipe lay is an ideal method for installing pipelines in a variety of environments.

The challenges of pipe lay

Pipe Lay refers to the process of installing pipelines underwater. It is a complex process that involves many challenges. One of the biggest challenges is dealing with the great depths at which these pipelines are installed.

The deeper the water, the more pressure there is on the pipe, which can make it difficult to lay the pipe properly. Another challenge is making sure that the pipes are properly aligned and welded together.

If there are any welding defect/ misalignment in the welds, it could cause problems later on. Finally, installing a pipeline is also a very time-consuming process, so making sure that everything is done correctly can be challenging.

Pipe Laying Procedure Step by Step

Pipe lay is a process of installing pipelines underwater. This can be done using a number of different methods, depending on the size and type of pipeline being installed. The most common method is to tow the pipeline behind a ship, but other methods include using barges or specially-designed cranes. Pipe lay is a complex and technical process, but it is essential for transporting oil and gas around the world.

Pipe Laying Procedure Step by Step by Welding on Vessel/ Barge

Pipe laying is a process used to install pipelines underwater. The most common type of pipe used for this purpose is welded on vessel (Barge) pipe. This type of pipe is made by welding two pipes together at a seam and then attaching them to a barge.

The first step in the pipe laying process is to weld the two pipes together. This is done by welding the pipes, onsite inspection & testing followed by corrosion protective coating.

Once the pipes are welded together, they are attached to the barge using clamps or other similar devices. The barge will then be towed to the desired location and sunk to the bottom of the water body.

Pipe Laying Procedure Step by Step on ground pipelines

1. The first step in any pipe laying project is to excavate a trench for the pipe. The depth and width of the trench will depend on the type and size of pipe being installed.

2. Once the trench is excavated, the next step is to lay down a bed of gravel or sand in the bottom of the trench. This will provide a stable base for the pipe.

3. The next step is to lay the pipe itself into the trench. This can be done by hand or with a machine, depending on the size and type of pipe being installed.

4. Once the pipe is in place, it needs to be secured so that it doesn’t move or shift during backfill or when water is flowing through it.


Pipe laying is the construction of pipelines to transport fluids or gases. There are three main types of pipe laying: buried, submerged, and elevated.

Buried pipe laying is the most common type of pipe laying. The pipes are buried underground and are typically made of steel or plastic. Submerged pipe laying is used for underwater pipelines. The pipes are submerged in water and are usually made of concrete or metal. Elevated pipe laying is used for pipelines that are above ground level. The pipes are elevated on supports and are typically made of steel or aluminum.

Pipe laying is a critical part of the infrastructure of many industries. It is important to choose the right type of pipe for the project, as each type has its own benefits and drawbacks.

Material Welding is run by highly experienced welding engineers, welding trainers & ASNT NDT Level III bloggers. We strive to provide most accurate and practical knowledge in welding, metallurgy, NDT and Engineering domains.