Flange for oil and gas industry
Which flanges are used in the oil and gas industry?
Connections via pipes is an important channel of transporting steam, fluids as well as gas from refineries to factories or across continents as well. Flanges prove to be an efficient method in connecting these pipes. Along with forging connections in a piping system, flanges regularly permit the worker with ease to clean, modify or inspect these systems. Different alloy grades are used to produce various flanges that are a part of a piping system in the oil and gas industry. Hence, these flanges are required to not only be durable, but they should also be easy to maintain and install. Below mentioned are some of the most commonly sighted flange types used in the oil and gas industry.
Weld Neck (WNRF)
Used in high pressure environments, a weld neck flanges are easily recognized because of their tapered hub. Moreover, weld neck flanges are particularly well suited to be used in repeat bending conditions. These flanges are attached to a piping system by means of welding the pipe to the neck of the flange. Therefore stainless steel grades that have good weldable properties are preferred for its manufacture. WNRF not only reduce the concentration of stress from the base of the hub but they also aid in the transference of stress from the flange to the pipe.
Slip on (SORF)
Designed to be used in low temperature, low pressure processes, slip on flanges are favoured by engineers in the oil and gas industry due to their economical value in comparison to the wnrf. This kind of flange is slipped over the pipe, following which they are welded both on the inside and outside in order to increase its strength and to prevent leakage.
A lap joint flange is essentially a two part attachment, which is preferred to be used in those processes where the frequent dismantling and space constraints are primary requirements. In this kind of attachment, lap joint stub end is welded to the pipe, and the loose backing flange it is used in conjunction with is slipped over the pipe. Since the backing flange is not in contact with the product in the piping systems, a less expensive material with moderate corrosion resistance and high hardness such as carbon steel could be used. Whereas the stub end needs to be a highly corrosion resistant material with excellent mechanical properties.
Used in circumstances where quick fixes are required, threaded flanges or as referred to as screwed flanges are produced with threaded bores, that aid in a simple and fast attachment. A threaded flange is generally attached to the pipe without the need of carrying out a welding operation due to the pre-existing threads. Typically seen in those processes where the pipes in the system are transporting air or water; a threaded flange is best used in low temperature and low pressure environments.
Produced without a bore in the center, the main purpose of using a blrf is to blank off the end of a piping system or valves or even pressure vessel openings. Blind flanges could also be used in conjunction with any other flange to isolate a piping system in the oil and gas industry. Furthermore, they make an excellent manhole, especially if they perform the task of terminating a flow in the piping system or in a vessel. These functions in the oil and gas industry dictate that the materials used in the manufacture of blind flanges have high tensile strength and good mechanical as well as corrosion resistance properties. This is especially due to the high pressure and high temperature conditions present in these applications.
Socket weld (SWRF)
Recommended to be used for low pressure and low temperature settings, the socket weld has a static strength which is equal to a Slip-on flange. Frequently a Socket-weld connection is made with the pipe by using a fillet weld performed on the outside of the flange. Socket weld flanges are designed to be used in processes where small bore piping is required. However, due to corrosion issues, these flanges are better avoided in some processes.