What type of welding is required on a 4" pipe?

The requirement for butt welds on a 4" pipe is primarily due to the need for a strong and continuous joint that can withstand high pressures and loads. Butt welding involves joining two pieces of pipe end-to-end, creating a seamless connection that is generally stronger than other types of welds. This method is particularly suitable for high-pressure applications, as it allows for uniform distribution of stress along the weld and minimizes potential weak points in the joint.

In applications like high-pressure boilers, where integrity and safety are critical, butt welding helps to maintain a stronger and more reliable connection compared to other methods. The increased cross-sectional area of the weld in a butt joint also provides better resistance to the forces acting on the pipe, such as thermal expansion and contraction, making it the preferred method for joining pipes of this size in demanding environments.