The Differences Between Forged Flanges and Cast Flanges


ARE FLANGES FORGED OR CAST?


Flanges can either be forged or cast. Both manufacturing methods have their advantages and disadvantages, depending on the application you have in mind for your flange. Here at Texas Flange, we primarily deal with forged flanges due to the outdated nature and lower standard of quality of cast flanges. Below, we will delve into the advantages and disadvantages of both forged steel flanges and cast iron flanges.


CAST IRON FLANGES


Casting is the process in which the metal is heated until molten then poured into a mold or vessel to create the desired shape. They are often used in cases that are too large, complicated, or other wise not suitable for forgings. Some of the advantages of flanges manufactured in this way include lower costs of production, the ability to make more intricate parts at lower costs, as well as having no true upper limit on size when it comes to your part.


There are, however, some drawbacks to cast iron flanges. The most important of these being how susceptible they are to internal defects. Due to this, cast flanges are not suitable for high pressure applications or applications in which the probability of corrosion is high. Despite advancement of casting technology and computer optimization of the casting process and designs, it is still difficult to meet the standards required for petrochemical industry applications.


FORGED STEEL FLANGES


Forging is the application of mechanical and thermal energy to steel billets or ingots to cause material to change its shape while still in solid form. Forgings offer consistency in composition and structure. Due to the nature of the production of forged flanges, the production costs are higher than that of cast flanges. Though they cannot have the complex shapes that cast flanges can be made in, their internal structure is more compact and therefore seldom have the defects the often affect cast flanges. Forging eliminates defects found in casting such as shrinkage, porosity, cavities, or cold pour issues.


Generally, forged flanges are stronger and more reliable than cast flanges because the grain flows of the steel are altered, confirming to the shape of the part. The tight grain structure of forgings makes the pieces mechanically stronger, and more resistant to general wear and tear than cast flanges. The higher quality, reliability, strength, and durability are why we deal mostly in forged flanges rather than cast flanges.


Here at Texas Flange, we offer forged flanges from 1/2″ nominal pipe size to 203″ OD in over a dozen different material grades. We value quality and strive to ensure that you are getting the right part for your application at a price and lead time that works for your business. Our salesmen work with you to ensure this. If you need a flange, give us a call at 281-484-8325 or send an e-mail to sales@texasflange.com to begin your inquiry. While you’re here , feel free to peruse our free informational blog posts, free 3-D and CAD drawings, or flange charts.


Different Types of Flanges and Their Uses


Used to connect valves, pipes and other equipment, flanges are forged rings that come in many different shapes and sizes and are used in a wide range of industries around the world. With so many varieties and specifications, it might be difficult at first to recognise which is the right one for you. Here's a rundown of some of the most common and popular types of the flange and their uses:


Weld Neck Flanges


Named for their protruding necks, these bulky flanges share the environmental stress of the pipe to which they are affixed and can, therefore, be used in extreme temperature or pressure situations.


Slip-on Flanges


Slip-on flanges slip onto the pipe – aptly named indeed – and are then welded on both the inside and outside. They're cheap, popular and best used in low-pressure, low-temperature applications.


Threaded Flanges


Threaded pipe flanges are similar in design to slip-ons but has a tapered thread, meaning it can be attached to pipes without welding. Like slip-on flanges, they're best used in low-pressure, low-temperature environments.


Blind Flanges


Blind flanges don't have a bore and are used to shut off sections of pipe. They're suitable for high-pressure applications, as well as for testing the flow of gas or liquid through a pipe.


Socket Weld Flanges


Typically used on small, high-pressure pipes like hydraulic pipes, socket weld flanges are able to accept pipe into the socket to create the fitting.


Orifice Flanges


Orifice flanges are used in conjunction with orifice plates to measure or restrict pressure or flow of gases and liquids in pipelines. They're often sold together with the plate and jack screws as a complete product.


The railway wheel


A typical railway wheel carries a load of about ten tonnes, roughly twice the equivalent for a road-going truck. The outer surface is called the tread. With a diameter typically of 1.0 m or less, the tread is roughly 100 mm wide. Like a pneumatic tyre, the railway wheel must handle the various forces needed to propel the vehicle forwards, slow it down, and hold it centrally on the track. But there are three striking differences. First, each railway wheel has a narrow lip or flange on the inside edge whose purpose is to stop the wheel from slipping off the rail. Second, the contact stresses between the wheel and the running surface are much more concentrated than those associated with a pneumatic tyre, reaching values that, paradoxically, exceed the yield point of the steel from which they are made. Third, railway wheels are almost always coupled together in pairs, each pair joined by a rigid axle to form what is known as a wheelset. A wheelset is extremely heavy by comparison with its equivalent on a road-going vehicle, and when you look at the various components, it’s not difficult to see why. Let's start with the disk.


One can think of a railway wheel as a solid disk whose tread is machined into the desired profile. In practice, some wheels have a separate ‘tyre’. The tyre, usually about 60 mm thick when new, is made of hardened steel. It is heated and pressed onto the wheel disk, where it shrinks as it cools and tightens its grip so that no bolts are needed to hold it in place. Ideally, for a smooth ride the diameter of the wheel should be as large as possible (see Section G1209), and in fact, the driving wheels on some early steam locomotives were 9 feet (over 2.7 metres) in diameter. They were magnificent examples of craftsmanship, and they needed to be large because they were driven by connecting rods, pistons and valve gear that were liable to fail if worked too fast, and a large wheel compensated by carrying the loco further along the track for each piston stroke. Later, when these limitations were overcome, the driving wheels were scaled down to a more manageable size. Nowadays, they are made of pressed steel, and for many the cross-section is wavy rather than flat. A wavy cross-section provides resilience and allows the rim to expand and contract slightly with changes in temperature without putting the disk under too much stress; useful properties for tread-braked wheels and those with separate tyres. Rubber inserts make the wheel more resilient still, helping to reduce any impact on the suspension when it passes over a gap in the rail.


What Is an Axle Shaft?


An axle shaft is a solid steel shaft that runs from the differential and gear set of an axle housing to the wheel. Used in two distinct configurations, the axle shaft can be a straight shaft with splines machined into each end to engage both the differential on one end and a drive flange on the other. It also can be a straight shaft with splines machined into the differential end and a flange on the other to mount a wheel to the axle. The first design is primarily used with a full floating axle design, while the latter is commonly used on passenger cars and light pickup trucks.


As a rule, this shaft is the thickest piece of steel on any given vehicle chassis. Designed to withstand the twisting force of the drive train as well as to support a portion of the vehicle's weight, an axle shaft is hardened to further enhance the natural strength of the steel used to manufacture the axle. Each specific shaft is hardened in a particular manner and design to best withstand the purpose for which it is designed to function. This hardening is the defining factor in creating an axle that will not break under stress from intended use.


On the typical passenger vehicle, the axle shaft has the wheel flange machined into the axle itself and comes as a single component. The wheel bearing is commonly pressed on to the outside end of the axle nearest to the wheel flange, and the wheel studs are installed through the flange. This design utilizes the wheel bearing to support the weight of the vehicle by placing the wheel bearing at the outer edge of the axle housing. In this configuration, the axle flange delivers power to propel the vehicle to the tire and wheel assembly.


Pressure Vessels


A pressure vessel is a closed container designed to hold gases or liquids at a pressure substantially higher or lower than the ambient pressure. Examples include glassware, autoclaves, compressed gas cylinders, compressors (including refrigeration), vacuum chambers and custom designed laboratory vessels.


Pressure vessels, autoclaves and steam sterilizers operating at pressures greater than 15 pounds per square inch gauge (psig) and larger than five cubic feet (ft3) volume fall within the Washington State Boiler and Pressure Vessel Code. As such, they have strict requirements for design, testing and approval.


The pressure differential between the inside and outside of the pressure vessel, over pressurized glass vessel whether created from chemical reaction, compressed gas, heating, chilling, cooling or vacuum, is a potential hazard. Many serious or fatal accidents have occurred when a pressure vessel or a component failed and generated flying projectiles or released hazardous broken glasswarematerials.