Flange End Connection

Today, Piping and Fabrication will talk about Flange-End Connection and I hope this topics will helpful for anyone who looking for knowledge about Piping System.

Flange Types

 The flange-end connection defines the way in which it is attached to the pipe. The following are commonly available standard flange end types:

Weld-Neck (WN) Flange. Weld-neck flanges are distinguished from other types by their long, tapered hub and gentle transition to the region where the WN flange is butt-welded to the pipe. The long, tapered hub provides an important reinforcement of the flange, increasing its strength and resistance to dishing. WN flanges are typically used on arduous duties involving high pressures or hazardous fluids.

The butt-weld may be examined by radiography or ultrasonic inspection. Usually, the butt-welds are subject to visual, surface, or volumetric examinations, or a combination thereof, depending on the requirements of the code of construction for piping or a component. There is, therefore, a high degree of reliability in the integrity of the weld. A butt-weld also has good fatigue performance, and its presence does not induce high local stresses in the pipework.

Socket-Weld (SW) Flange. Socket-weld flanges are often used on hazardous duties involving high pressure but are limited to a nominal pipe size NPS 2 (DN 50) and smaller. The pipe is fillet-welded to the hub of the SW flange. Radiography is not practical on the fillet weld; therefore correct fitting and welding is crucial. The fillet weld may be inspected by surface examination, magnetic particle (MP), or liquid penetrant (PT) examination methods.

Slip-on Flanges. Slip-on flanges are preferred to weld-neck flanges by many users because of their initial low cost and ease of installation. Their calculated strength under internal pressure is about two-thirds of that of weld-neck flanges. They are typically used on low-pressure, low-hazard services such as fire water, cooling water, and other services. The pipe is ‘‘double-welded’’ to both the hub and the bore of the flange, but, again, radiography is not practical. MP, PT, or visual examination is used to check the integrity of the weld. When specified, the slip-on flanges are used on pipe sizes greater than NPS 2½  (DN 65).

Composite Lap-Joint Flange. This type of flanged joint is typically found on high alloy pipe work. It is composed of a hub, or ‘‘stub end,’’ welded to the pipe and a backing flange, or lapped flange, which is used to bolt the joint together. An alloy hub with a galvanized steel backing flange is cheaper than a complete alloy flange. The flange has a raised face, and sealing is achieved with a flat ring gasket.

Swivel-Ring Flange. As with the composite lap-joint flange, a hub will be buttwelded to the pipe. A swivel ring sits over the hub and allows the joint to be bolted together. Swivel-ring flanges are normally found on sub–sea services where the swivel ring facilitates flange alignment. The flange is then sealed using a ring-type joint (RTJ) metal gasket.

Blind Flange. Blind flanges are used to blank off the ends of piping, valves, and pressure vessel openings. From the standpoint of internal pressure and bolt loading, blind flanges, particularly in the larger sizes, are the most highly stressed of all the standard flanges. However, since the maximum stresses in a blind flange are bending stresses at the center, they can be safely permitted to be stressed more than other
types of flanges.

Waiting for Raw Water (Actiflo) Pic. 1 Re-Start Again

It's been too long for Piping and Fabrication to wait Raw Water Line drawing 1 to continue again, there is still much work to do on Raw Water Line, including huge pipe size which is DN800 or 32 inch that we have to fabricate and erection.

Below here is an isometric drawing for Raw Water Line and almost 70% from that line is not finish yet, and we hope we can have enough man power to finish those line.

Isometric for Raw Water Line drawing No. 1

Can we finish those line in time? we hope we can do it, it's up to many circumstances, technical or non technical situation.

This is Piping & Fabrication write for you all just for information and share. Thanks for visiting!

THE PROCESS OF JOINT INTEGRITY

THE PROCESS OF JOINT INTEGRITY
This is what we want to see and this is also what Piping and Fabrication mean to keep ON AIR until now, to provide us with valuable information like this, enjoy it.

To assist in managing a process, ask yourself the following questions: why, what, who, and how? Why do we need a Flange Joint Integrity program? This was addressed in the previous section, ‘‘Cost of a Leak.’’ The stakes are enormous. A Flange Joint Integrity program will help improve plant safety and reliability while reducing its environmental impact. What do we need to control? The operating environment, the components, and assembly all need to be controlled. Who do we need to control? The designers, field operatives, and supervisors. How do we control? Train personnel to required competency. Design components using latest engineering standards. Develop best practices for assembly and maintenance. Implement a quality assurance program that provides traceability and ensures compliance to specifications. There are over 120 variables that affect flange joint integrity. These can be controlled through the following categories:
● Environment (internal and external)
● Components
● Assembly

The internal environment outlines the design and operating conditions of temperature, pressure, and fluid. With the external environment, consideration is given to location of the flange, whether it is operating in air or sub-sea, and externally applied piping loads. An understanding of the environment is crucial to the design and selection of the appropriate components with the correct assembly methods. The components include the most appropriately designed and selected flange, gasket, and bolting, commensurate with the risk dictated by the environment. Assembly includes checking the condition of the components and proceeding according to established procedures. Proper assembly requires that
● Flange faces meet the standards
● Gasket-seating stress is achieved
● Bolts, nuts, and gaskets are free of defects
● Appropriate lubrication is used

Execution requires trained, competent people using the correct tools and following procedures.

Thanks for Visiting Piping and Fabrication and see you always.

Fabrication Practices which is Cutting and Bevelling

Fabrication Practices

Now Piping and Fabrication will start again to write about all what we need in Piping System, and now we entering with Fabrication Practices which is Cutting and Beveling. 

The methods of cutting plate or pipe to length can be classed as mechanical or thermal. Mechanical methods involve the use of saws, abrasive discs, lathes, and pipecutting machines or tools. Thermal methods are oxyfuel gas cutting or electric arc cutting. Oxyfuel gas cutting is a process wherein severing of the metal is effected by the chemical reaction of the base metal with oxygen at an elevated temperature. In the cutting torch, a fuel such as acetylene, propane, or natural gas is used to preheat the base metal to cutting temperature. A high-velocity stream of oxygen is then directed at the heated area resulting in an exothermic reaction and severing of the material. Oxyfuel gas cutting is widely used for cutting carbon steels and low alloys. It does, however, lose its effectiveness with increasing alloy content. For higher alloy materials, some form of arc cutting is required. Plasma arc cutting is the process most frequently employed. It involves an extremely high temperature (30,000 to 50,000°K), a constricted arc, and a high-velocity gas. The torch generates an arc which is forced to pass through a small-diameter orifice and concentrate its energy on a small area to melt the metal. At the same time a gas such as argon, hydrogen, or a nitrogen-hydrogen mixture is also introduced at the orifice where it expands and is accelerated through the orifice. The melted metal is removed by the jetlike action of the gas stream.

Because oxyfuel gas and arc cutting involve the application of heat, preheating may be advisable in some cases. Weld end bevels can also be prepared by the mechanical or thermal methods just described. Both mechanical and thermal methods are used to apply the V bevel, which is used in the vast majority of piping applications. For compound and U bevels or those which may involve a counterboring requirement, horizontal boring mills are most appropriate. Various factors to be considered in selecting a weld end bevel are discussed in the section, ‘‘Welding Joint Design.’’