Manifolds are widely used in the oil and gas industry for the distribution of process fluids such as oil, gas, and water. Manifolds are designed to either merge multiple junctions into a single channel or divide one flow line to multiple outputs. The size of a manifold is selected by process engineers based on the flow rate passing through the manifold. Manifolds used in the offshore industry are made in 22Cr duplex instead of carbon steel to save thickness and weight. The manifolds described in this paper are either made of welding wrought tees or designed using a standard pipe as a header and welding olets to the pipe header. Mechanical joints (hubs and clamps) instead of standard ASME flanges are used for closing some of the manifold header ends as well as some of the branch connections to save weight and space. Traditionally, welding techniques and preparation of the welded ends has been done as per ASME B16.25, the common standard for butt welded connections in piping systems, including manifolds. However, narrow gap welding is an advanced welding end preparation in which the angle of the bevel end fitting is 7° to the vertical line. The advantages of narrow gap welding include using less weld electrodes, a faster welding process, and less heat input. This paper presents a method for calculating welding consumables volume and weight in one meter. The result shows that the amount of welding electrodes used for standard ASME welding is more than double the amount used for narrow gap welding.

manifold, manufacturing process, material selection, welding, oil and gas, offshore