Pipeline technology has evolved in line with improved safety procedures. Although modern flanges and pipe fittings are basically the same design as their predecessors, they are made of far superior alloys, minimising risk of accidents and systems failure.
Today’s pipe flanges and fittings are made to set industry standards. These are the ultimate reference tool for everyone connected to the industry, including managers, contractors and specialist manufacturers. The earliest pipelines and flanges were made from brittle, corrodible cast and wrought iron. These pipe fittings are now museum pieces. By 1900, steel had replaced iron. Then there was stainless steel. Over the years, stainless steel alloys have been continually modified to get where we are today – with pipe fittings manufactured in high-strength, low corrosion alloys such as titanium and super duplex. They are custom designed to meet individual industry standards.
Early pipelines were joined using screwed collars. However, as both pressures and pipe diameters increased so new pipe fittings, such as bolted flanges, were developed. Today, there are literally dozens of different flanges- each designed for a specific task or set of environmental conditions. Weld-neck pipe flanges are widely used in the oil and petroleum industries, but there are also screw-on, lap-joint, swivel-ring, spacer, cross-over and adaptor flanges.
However, advanced the technology, pipe flanges can still fail – modern alloys lengthen their lifespan, they don’t make them totally infallible! We at Chemipetro pride ourselves that we hold practically every industrial fitting in stock, and can ship them out to you at the touch of a button.
The evolution of pipe flanges
January 28th, 2010The importance of earthquake research to the Water Industry
January 26th, 2010Water is distributed in steel pipes, either 20 or 40 ft (6 or 12 m) long. Each piece is coupled to the next, either by direct welding or via pipe fittings or flanges (called couplers.) There are several ways to couple water pipes together:
• They can be abutted directly together, using a single circumferential weld
• They can be sleeved with flanges that extend over the ends of the two pipes, creating two circumferential welds. This is known as the girth welded joint.
• They can be connected via pipe fittings (called bell housings) which are factory formed in the wall of one pipe, and then welded to the adjacent pipe. This is the most common coupling used in water systems, combining the benefits of single welds that incorporate flanges
Affordable pipe fittings are a necessary part of delivering household drinking water, and a lot of research has gone into improving their design, particularly in areas prone to earthquakes. A common cause of fatalities in these regions is lack of a clean water supply. Often, the cause is not fractured pipes, but failure at the pipe flanges.
A bell housing is made by inserting a mandrel into one end of the pipe, and expanding it until room is created to insert the adjoining end. This means each pipe section has a bell housing at one end, and a prismatic spigot joint at the other. Understanding the how compression, tension, pressure loading and cyclic stresses affects these joints is an important concern in urban areas prone to earthquakes. Research is concentrated on new pipe fittings with improved stress resistance.
We at Chemipetro supply pipe flanges for an entire range of industries, using alloys that are both strong and corrosion-resistant, such as super duplex.
Gas and oil pipelines are needed
January 24th, 2010Despite the warnings on global warming, millions of cubic metres of gas, crude oil and gasoline are consumed each day.
The American usage of the term for petroleum is deliberate – the USA is a major consumer and producer of all these products. Together with Canada, the US consumed 23 million barrels of crude oil and petroleum products, and 67 billion litres of natural gas each day in 2006, accounting for 63% of total US energy consumption.
The refineries and processing plants are finding ever greener ways of refining and distributing their products, and consumers are finding ever more efficient ways of restricting their usage, but the fact remains that gas, oil and petroleum are the only cheap, efficient way to produce enough energy for everyone to use. Natural gas and crude oil fields are located a long way from the processing plants and oil refineries, which in turn are located a long way from consumers. Thus, there must be a vast network of pipelines to transport the raw product to the plants, and the refined product to the market place. Pipe fittings and flanges are a necessary part of the process.
However, despite hefty fines and new safety legislation, there are still hundreds of accidents and leakages each year, caused by poor maintenance and cost-cutting methods. Corroded flanges and leaking pipe fittings are not only dangerous and bad for the environment – they’re wasteful, too.
By offering pipe fittings in the latest hyper-resistant alloys at affordable cost, we at Chemopetro can prove that there is a better way to do things.
Keeping everything under control
January 22nd, 2010Liquids are moved through pipelines in measured, regular batches. This is done by automated processing, at a set speed – around 6 km per hour. In the case of natural gas, a constant system is used, and the speed is much faster – around 40 km per hour.
Obviously, a lot of operating systems are in place to do this. A system of centrifugal compressors moves the product through the pipelines. At regular intervals, the systems are given thorough maintenance checks inside and out, with corrosion of flanges etc attended to either by repair or replacement. This is also the time upgrades are done.
Pipeline operation is a complicated system, employing many trained staff. The control centre personnel handle system monitoring and the scheduling, controlling and recording of batch receipt and delivery. They also handle any emergencies that crop up. It is their job to monitor things like pressure and flow rates. This information is sent to the control centre via remote SCADA (supervisory control and data acquisition) systems. From the point of view of pipe fittings, it is their job to detect and act upon faults and leaks that develop.
Staffs maintain and repair pipelines, pumps, compressors, valves, flanges, pipe fittings and electronic equipment. In other words, their job involves a direct, “hands on” approach to leaking pipe flanges and other such problems.
Emergency equipment failure can lead to sudden sharp pressure drops, which will trigger automatic shutdown of the entire system. By supplying our customers with high quality pipe flanges, joints and other pipe fittings the moment they are needed, we at Chemipetro ensure this doesn’t happen.
Where do flanges and pipe fittings come into pipeline management?
January 20th, 2010People forget that there’s a lot more to a pipeline than a long tube of welded joints. Where those joints are at risk of stress fractures, pipe flanges are installed. At either end, and in the course of the pipeline itself, are numerous operating systems, maintenance sheds and branch-lines. All of which adds up to an awful lot of flanges and pipe fittings to keep maintained.
Pipeline operators don’t usually own what they are shipping. The owners are the oil and gas refineries, industrial plants and utilities companies, who pay the pipeline company to ship their products to other areas.
Pipeline revenue depends on how much is shipped out. To ensure their products are delivered reliably, shipping companies usually pay the pipeline a fixed volume per month. However, this gives the pipeline less revenue to maintain their lines. Similarly, lower shipping orders mean less revenue for maintaining the plants and refineries. In other words, in both cases throughput is generally tweaked to its absolute max – placing the flanges and pipe fittings under tremendous pressure.
It makes sense that, when throughput is high, the quality of the flanges and pipe fittings must be high also. So companies making pipe fittings and flanges for these industries must address this issue.
To keep costs low, industries often ignore potential failure points, and use cheap alloys in place of, for example, Duplex pipe fittings. By providing industrial clients with high quality flanges and fittings, we at Chemipetro are encouraging them to take a responsible attitude towards systems maintenance.
Why do pipelines fail?
January 18th, 2010Pipelines can be improved by the use of strong, highly resistant alloys such as Super Duplex, but even so the cost of system breakdown remains quite high. So what are the causes of pipeline failures?
The most common cause of accident and failure is damage from outside forces, with corrosion coming a close second. This means the two biggest areas of concern i.e. corrosion and stress resistance, must be addressed together. This is why Duplex alloys are so superior – they do this job admirably. By combining the attributes of ferrous and arsenate compounds within the same metal, they convey the benefits of both.
This lengthens the life of flanges, and therefore of pipelines, but doesn’t solve the problem completely. The earth’s climate is becoming ever more unstable- with floods, high winds and temperature variations all playing their part. On top of this you have earth movements via earthquakes and heavy vehicular traffic, fire, explosion damage by a third party (like terrorists) and excavation damage.
The latter is a particular problem. Records show that, when it comes to damage to gas and hazardous liquid pipelines, a major amount of damage is caused by an accidental “hit” directly on the line by excavators working nearby.
This kind of problem looks set to stay, unfortunately. However, it’s not all bad news. Replacement of a fractured pipe or component gives you the opportunity to upgrade pipe fittings and other components at low cost. We at Chemipetro have high quality industrial pipe flanges and fittings in the very latest, impact and corrosion resistant alloys.
Laying a pipeline – valves and pipe fittings
January 16th, 2010Pipelines need to be checked and maintained; for this, valves and special pipe fittings must be installed as the pipeline is built. It is essential the pipeline is strong, but easy to maintain, and so shut-off valves and flanges are used to isolate areas for maintenance and gain easy access.
Even the best laid pipelines corrode and leak – often around flanges and fittings. So the industry is constantly coming up with new alloys and welding techniques to lengthen the life of the structure. Often, when pipe fittings are replaced, it isn’t because they have reached the end of their life but because a better quality product came along. The cost of this must be weighed against the cost of man hours spent checking less reliable pipe fittings, and the environmental and company cost of a pressure leak.
Pipelines are not laid on top of earth. A trench is dug and the pipe covered over, unless it is to run underwater. This causes major headaches in design, because the pipeline is effectively hidden from view – so how can you tell when the flanges need attention? Various geophysical, automated mechanical and electronic systems have been developed to give early warning of problems but, again, the use of high quality alloys such as Duplex is the surest way to ensure pipe fittings give long and reliable service. Reliability in this industry is obviously of paramount importance.
We at Chemipetro manufacture a wide range of pipe fittings for all sorts of industrial systems including refineries, chemical plants and undersea pipelines.
Techniques used in pipeline laying
January 14th, 2010When pipelines are laid, the pipes are positioned end to end, and welded in place – often using specialised flanges. Wherever there is a join in a pipe, the risk of corrosion is introduced. This can be lessened by the use of specialised alloys, and bending pipes rather than using angled pipe fittings.
New alloys are constantly being sought which are stronger and more corrosion resistant than those already on the market. However, there is often a payoff. Some alloys are immensely stress resistant, but don’t bend easily, for example. Others are highly malleable, but corrode.
Pipe bending is the most efficient way of switching direction in a pipeline without the use of pipe fittings. Specialised bending machines ensure the pipe retains its strength and contours. However, the lengths of pipe still have to be welded together. To reduce corrosion, low carbon steels are used. However, these have low ‘weldability.’ The best alloys are Duplex and Super Duplex stainless steels, which are corrosion resistant and weld well at low temperatures. At high temperatures there is a risk of crystallisation, which destroys the anti-corrosion effect. To avoid this, pipe flanges are often used across the joint.
Flanges are extensively used in undersea pipelines, where pressure stresses and corrosion are major problems. The pipes can be manufactured in prefabricated lengths on shore, using pipe flanges, before installing underwater. This keeps joint welding to a minimum.
We at Chemipetro supply flanges in Duplex and Super Duplex for a wide range of uses, including undersea gas and oil pipelines.
The stages of laying a pipeline
January 10th, 2010Pipelines are laid in sections, each of which is connected to the next with welded flanges. Pipelines have to go round boundaries, avoid obstacles and branch off in various directions. A combination of bending techniques and pipe fittings ensure this can happen – all meticulously planned on a PC.
The pipe flanges and fittings in pipelines are composed of super-strong, highly resistant alloys such as Super Duplex. Because pipelines are welded, the flanges must be resistant to the heat used – if a pipeline is going to fail, it will be at these joints.
Laying a pipeline takes preparation. Once permission has been granted, the site is surveyed and the right-of-way cleared, fenced and graded. The right-of-way is where all construction occurs. It is also where bulk items, such as pipes and pipe fittings, are delivered. For this reason, gravel pads are laid to allow passage of vehicles, personnel, supplies and equipment. Once the pipeline is laid, the company use this right-of-way for maintenance, inspection and repairs – replacing pipe flanges, for example.
The next job is the “hauling and stringing” of the pipe: lengths of steel pipe are moved from the stockpile to the right-of-way and arranged ready for welding. As the pipeline must cross hills, curve round reservoirs and avoid ancient monuments, it has to be curved. Specialised pipe bending techniques are used wherever possible to achieve this: whenever pipe fittings are introduced into a pipeline, it’s a potential weak point.
We at Chemipetro understand the importance of using strong, highly resistant steel alloys and top quality manufacturing techniques for industrial pipe fittings.
API weld-neck pipe flanges
January 6th, 2010API (American Petroleum Institute) flanges are used in high-pressure refineries to carry volatile products such as oil and natural gas. API flanges are manufactured to withstand far higher pressures than pipe flanges in other categories, for example ANSI.
API pipe flanges are further classified according to specifications laid down in API manuals. API Spec 6A flanges, for example, are commonly used in the gas and oil industries. Their specifications are laid down in the API publication “Industry Specification for Wellhead and Christmas Tree Equipment.” In the context of pipe flanges, Christmas Trees are not festive decorations but assemblies used to cap off the heads of oil or gas wells. The name comes from the bristling array of pipe fittings, which gives them the appearance of crudely drawn pine trees.
As you can imagine, the pressures these flanges must endure are tremendous and a failure could be catastrophic. For this reason the standards applied are very high. Only companies granted a licence from the API can apply the API Spec classification to their products – this ensures the product quality is maintained and flanges are traceable to their point of origin.
API flanges are further differentiated into sub-classes. For example, API Spec 6A, 6B pipe flanges have ring grooves sized to accept R and RX ring gaskets. Weld-neck flanges of this specification have restricted, rather than full bores to match set pipe sizes. For example, a 4 1/16” 5M 6B flange is compatible with a 4” schedule 160 pressure pipe of 4 ½” outside diameter.
We at Chemipetro have a huge range of API flanges created in the very toughest alloys, such as Titanium and Duplex.