April 15th, 2010
As a supplier and manufacturer of high-quality pipe flanges for the petrochemical industry, we at Chemipetro understand the importance of caring for our flanges and pipe fittings once they’re installed.
All flanges need regular maintenance, or you will start to get decreased performance from other components on your site. It’s essential you eliminate problems at their source, as soon as they arise. Not only will this improve plant efficiency, it will create a safer working environment and save on running and repair costs. A large number of fires and explosions start as a result of leaking or poorly welded pipe fittings.
No matter how high the quality of the alloys, it is essential you protect flanges, gaskets and other components from their environment as much as possible. This starts by reducing corrosion to an absolute minimum. Using corrosion resistant alloys, such as super duplex, has reduced corrosion substantially – but the annular seal on the outer diameter of flanges can still be vulnerable to moisture and dirt. Once these creep in, eventually it will lead to corrosion and degradation around the gasket area.
You should also remember that welded joints are more vulnerable to corrosion than other areas of pipe fittings, even if tough stainless steel alloys are used. Excessive corrosion of flanges is dangerous, and if they have to be replaced it can lead to plant shut-down. To reduce this risk, use flange protectors to stop dirt and moisture attacking the joints.
While strong, corrosion-resistant alloys like duplex steel will ensure you get long life from the pipe flanges you buy from us atChemipetro, they will last even longer if you remember these few basic rules.
Tags: corrosion resistant alloys, Pipe Fittings, Pipe Flanges, Super Duplex, weld neck flanges, welded joints
Posted in Duplex | No Comments »
April 9th, 2010
We at Chemipetro supply a wide range of pipe flanges for the petrochemical industry, of both welded and non-welded design. Slip-on flanges are an example of a welded fitting. They are designed to go over the end of a pipe, which is then welded on both sides to create a leak-proof seal. Quick and easy to install, they are manufactured by us in a range of alloys including super duplex steel.
The main drawback with slip-on flanges is that they are not suitable for high temperature or high pressure applications, due to the lack of strength at the joint. While there is a certain amount of flexibility with metal contraction and expansion, they will not stand up to extreme conditions.
Weld-neck flanges are the most common type used in industry, and are especially useful in high pressure or high temperature systems. They have a long, tapered hub which gradually thickens towards the butt weld end, i.e. where the flange joins the pipe. This design reinforces the weld, thus making this type of flange superior in terms of strength and distortion resistance (dishing).
Lap-joint flanges lie somewhere between the two other types. The flange attaches to a special stub-end sleeve, which has a narrow shoulder (hub) one end and a weld bevel at the other. The rear face of the hub has an interior fillet to join it to the flange. The flange itself lacks the raised face of other pipe flanges, and slips on to the stub-end sleeve before the sleeve itself is welded into place – the flange itself in non-welded. Lap-joint pipe flanges are therefore free to spin, making them easy to align and dismantle.
Tags: Flanges, lap joint flanges, Pipe Fittings, Pipe Flanges, weld neck flanges
Posted in Pipe Flanges | No Comments »
February 11th, 2010
In the 1990s, there was a massive fire in the town of Fortaleza, Brazil. The cause was a flange failure in the city’s petrochemical plant. A similar thing happened again in 2004, and leakages of noxious chemicals are a continued risk for the town’s population, not least of all its children.
Despite advances in technology and the development of modern alloys – for example, super duplex – the problems remain the same. This is largely because the mechanisms governing site safety (like budget, flange suppliers and human error) remain the same.
The cause of the original fire was fractures in the fixation screws of a valve flange during operation. Hydrogen and hydrogen sulphide gas escaped and caused an explosion. An inspection afterwards revealed the weld-necked flanges used in the plant were of poor quality and constructed from normal forged material. Some were not even of this grade, but made from rolled or cast iron. Factors affecting the failure included: diverse manufacturing practices, environmental cracking, design issues, crack-like imperfections due to poor forging practices and poorly constructed welds.
The Fortaleza problem hasn’t gone away. The town has been developed into a major tourist resort, but the poor quality flanges remain. The potential for accidents therefore endures. It is easy to say that this is a practice restricted only to poorer countries, but Brazil is an emerging economy and many of the plants are owned by multinational conglomerates. They are located where they are because labour costs and running expenses are low.
We at Chemipetro supply high quality flanges all over the world, at affordable prices.
Tags: flange suppliers, Flanges, industrial pipe flanges, Pipe Flanges, weld neck flanges
Posted in Flanges | No Comments »
September 8th, 2009
The purpose of a flange is to connect to either two pipes together, a pipe to a valve or tee or to connect a pipe to a choke or any other piece of equipment.
These are the various types of flanges and their uses.
1. Blind Flanges. A blind flange has no bore. It is used in applications to close the ends of piping systems, and this type of flange also allows easy access to the line once it has been sealed. Blind flanges may be machined in order to accommodate a pipe of nominal size which has been reduced. The reduction can take the form of either a thread or a weld.
2. Weld Neck Flanges. This type of flange is drilled to a point where the wall thickness is machined to match the dimensions of the pipe. The lighter the pipe is the larger the bore must be, and visa versa. These flanges can be used for high pressure, cold or hot temperature applications.
3. Slip-On Flanges. A slip-on flange is one that is bored to a slightly larger size than the pipes outer diameter. The pipe then slips into the flange and is then welded inside and out in order to prevent leaks.
4. Orifice Flanges. The function of these flanges is to meter the flow of either gas or liquids in the pipe. Jack screws are needed to spread the flange apart in order to change an orifice plate that is situated between two flanges.
5. Socket Weld Flanges are similar to slip-on flanges. The difference is that a counter bore in required which is slightly bigger than the outer diameter of the pipe which allows the pipe to be inserted.
Here at Chemipetro, each of the aforementioned types of flange are stocked to suit any possible specification.
Tags: Blind flanges, Flanges, slip-on flanges, socket weld flanges, weld neck flanges
Posted in Flanges | No Comments »
September 1st, 2009
Although many different flange standards are found worldwide, the principle behind each is to allow the easy inter-changeability and functionality. For this reason, pipe flanges are designed around standard measurements.
These include world standards, such as ASA/ANSI for the USA and BS10 for Britain and Australia. Amongst these standards are manufacturing specifications that stipulate the materials used and their pressure ratings.
BS10 Standards for Pipe Flanges
These standards specify the requirements needed for the manufacture of pipe flanges. The relationship between temperature and pressure according to specific materials is illustrated.
In many cases, BS10 pipe flanges are not interchangeable with international standard flanges. International standards also differ in regard to pressure classes. Each international class will show different pressure ratings. They also show different temperature ratings for different materials. While pressure classes are developed in accordance to their use, they may at times be unique for certain industries or concerns. For instance a contractor or a process plant owner.
Pipe flange faces are manufactured to standard dimensions. They are also manufactured with different faces. While they are typically flat they can also be take be styled as raised, tongue and groove or ring joint.
Their designs differ as well and can take the form of either welding neck pipe flanges, slip-on, boss pipe flanges, lap joint, socket weld, threaded or blind pipe flanges.
ANSI Standards
ANSI designations are designated a number which is proceeded by a ‘#” symbol. This number does not relate to a pipe flanges’ pressure rating or to its weight in pounds; instead, it relates to the class of pipe flange. A pipe flange with a rating of ANSI #300 is rated for a test pressure of 740 psi within a certain range of working temperature.
At Chemipetro, we supply a standard range of high quality pipe flanges for whatever needs you may have.
Tags: blind pipe flanges, Flanges, Pipe Fittings, Pipe Flanges, weld neck flanges
Posted in Pipe Flanges | No Comments »
